Report bytes and transactions actually sent downtream

From 0bdaca3d1bb95cb834d45137eddaaa58fe1646b9 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH] Report output plugin statistics in pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output plugin statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- plugin_filtered_bytes is the amount of changes filtered out by the
  output plugin
- plugin_sent_txns is the amount of transactions sent downstream by the
  output plugin
- plugin_sent_bytes is the amount of data sent downstream by the output
  plugin.

The prefix "plugin_" indicates that these counters are related to and
maintained by the output plugin. An output plugin may choose not to
initialize LogicalDecodingContext::stats, which holds these counters, in
which case the above columns will be reported as NULL.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Additionally report name of the output plugin in the view for an easy
reference.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Author: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++++---------
 contrib/test_decoding/sql/stats.sql           | 15 ++--
 contrib/test_decoding/t/001_repl_stats.pl     | 18 +++--
 contrib/test_decoding/test_decoding.c         |  2 +
 doc/src/sgml/logicaldecoding.sgml             | 27 +++++++
 doc/src/sgml/monitoring.sgml                  | 58 ++++++++++++++
 src/backend/catalog/system_views.sql          |  4 +
 src/backend/replication/logical/logical.c     | 24 +++++-
 .../replication/logical/logicalfuncs.c        |  7 ++
 .../replication/logical/reorderbuffer.c       |  3 +-
 src/backend/replication/pgoutput/pgoutput.c   | 21 +++++
 src/backend/replication/walsender.c           |  7 ++
 src/backend/utils/activity/pgstat_replslot.c  |  7 ++
 src/backend/utils/adt/pgstatfuncs.c           | 26 ++++++-
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  4 +
 src/include/replication/logical.h             |  1 +
 src/include/replication/output_plugin.h       | 13 ++++
 src/include/replication/reorderbuffer.h       |  1 +
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 src/test/regress/expected/rules.out           |  6 +-
 src/tools/pgindent/typedefs.list              |  1 +
 22 files changed, 275 insertions(+), 65 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index de6dc416130..d19fe6a1c61 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | t          | t
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+-- total_txns may vary based on the background activity but sent_txns should
+-- always be 1 since the background transactions are always skipped. Filtered
+-- bytes would be set only when there's a change that was passed to the plugin
+-- but was filtered out. Depending upon the background transactions, filtered
+-- bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_txns | total_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+------------+-------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | t          | t           |                1 | t          | t
+ regression_slot_stats2 | t          | t           | t          | t           |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t          | t           |                1 | t          | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_txns | total_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+------------+-------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | f          | f           |                  |            | 
+ regression_slot_stats2 | t          | t           | t          | t           |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t          | t           |                1 | t          | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | f          | f
- regression_slot_stats3 | t          | t           | f          | f
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_txns | total_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes 
+------------------------+------------+-------------+------------+-------------+------------------+-------------------+-----------------------
+ regression_slot_stats1 | t          | t           | f          | f           |                  |                   |                      
+ regression_slot_stats2 | t          | t           | f          | f           |                  |                   |                      
+ regression_slot_stats3 | t          | t           | f          | f           |                  |                   |                      
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index a022fe1bf07..1077cea5855 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,21 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+-- total_txns may vary based on the background activity but sent_txns should
+-- always be 1 since the background transactions are always skipped. Filtered
+-- bytes would be set only when there's a change that was passed to the plugin
+-- but was filtered out. Depending upon the background transactions, filtered
+-- bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +51,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..76dd86fc420 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, plugin_filtered_bytes may be greater than 0. But it's not
+	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
 		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+			   total_bytes > 0 AS total_bytes,
+			   plugin_sent_txns > 0 AS sent_txn,
+			   plugin_sent_bytes > 0 AS sent_bytes,
+			   plugin_filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index bb495563200..a77309ce438 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -173,6 +173,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	data->only_local = false;
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
 	opt->receive_rewrites = false;
@@ -310,6 +311,7 @@ static void
 pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
 {
 	OutputPluginPrepareWrite(ctx, last_write);
+	ctx->stats->sentTxns++;
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
 	else
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index 593f784b69d..a84c2f00195 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -774,6 +774,33 @@ typedef struct OutputPluginOptions
       needs to have a state, it can
       use <literal>ctx-&gt;output_plugin_private</literal> to store it.
      </para>
+
+     <para>
+      The startup callback may initialize <literal>ctx-&gt;stats</literal>,
+      typically as follows, if it chooses to maintain and report statistics
+      about its activity in <structname>pg_stat_replication_slots</structname>.
+<programlisting>
+ctx->stats = palloc0(sizeof(OutputPluginStats));
+</programlisting>
+      where <literal>OutputPluginStats</literal> is defined as follows:
+<programlisting>
+typedef struct OutputPluginStats
+{
+      int64   sentTxns;
+      int64   sentBytes;
+      int64   filteredBytes;
+} OutputPluginStats;
+</programlisting>
+      <literal>sentTxns</literal> is the number of transactions sent downstream
+      by the output plugin. <literal>sentBytes</literal> is the amount of data
+      sent downstream by the output plugin.
+      <function>OutputPluginWrite</function> is expected to update this counter
+      if <literal>ctx-&gt;stats</literal> is initialized by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes in bytes that are
+      filtered out by the output plugin. Function
+      <literal>ReorderBufferChangeSize</literal> may be used to find the size of
+      filtered <literal>ReorderBufferChange</literal>.
+     </para>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 823afe1b30b..d8efae0cfd2 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1545,6 +1545,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1644,6 +1655,53 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is handed over to
+        the output plugin, e.g. the changes filtered by origin. The count is
+        maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>. It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transctions sent to
+        the decoding plugin. Hence this count is expected to be lesser than or
+        equal to <structfield>total_txns</structfield>.  The count is maintained
+        by the output plugin mentioned in <structfield>plugin</structfield>.  It
+        is NULL when statistics is not initialized or immediately after a reset or
+        when not maintained by the output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes sent downstream for this slot by the
+        output plugin after applying filtering and converting into its output
+        format. The count is maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>.  It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index f6eca09ee15..930e6309d71 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1053,6 +1053,7 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
@@ -1061,6 +1062,9 @@ CREATE VIEW pg_stat_replication_slots AS
             s.stream_bytes,
             s.total_txns,
             s.total_bytes,
+            s.plugin_filtered_bytes,
+            s.plugin_sent_txns,
+            s.plugin_sent_bytes,
             s.stats_reset
     FROM pg_replication_slots as r,
         LATERAL pg_stat_get_replication_slot(slot_name) as s
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 7e363a7c05b..9d77e57af65 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1952,13 +1952,14 @@ void
 UpdateDecodingStats(LogicalDecodingContext *ctx)
 {
 	ReorderBuffer *rb = ctx->reorder;
+	OutputPluginStats *stats = ctx->stats;
 	PgStat_StatReplSlotEntry repSlotStat;
 
 	/* Nothing to do if we don't have any replication stats to be sent. */
 	if (rb->spillBytes <= 0 && rb->streamBytes <= 0 && rb->totalBytes <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " (%s) %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1967,7 +1968,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamCount,
 		 rb->streamBytes,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 stats ? "plugin has stats" : "plugin has no stats",
+		 stats ? stats->sentTxns : 0,
+		 stats ? stats->sentBytes : 0,
+		 stats ? stats->filteredBytes : 0);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1977,6 +1982,15 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_bytes = rb->streamBytes;
 	repSlotStat.total_txns = rb->totalTxns;
 	repSlotStat.total_bytes = rb->totalBytes;
+	if (stats)
+	{
+		repSlotStat.plugin_has_stats = true;
+		repSlotStat.sent_txns = stats->sentTxns;
+		repSlotStat.sent_bytes = stats->sentBytes;
+		repSlotStat.filtered_bytes = stats->filteredBytes;
+	}
+	else
+		repSlotStat.plugin_has_stats = false;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1988,6 +2002,12 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->streamBytes = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	if (stats)
+	{
+		stats->sentTxns = 0;
+		stats->sentBytes = 0;
+		stats->filteredBytes = 0;
+	}
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index ca53caac2f2..00a53d1857e 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -89,6 +89,13 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/*
+	 * If output plugin has chosen to maintain its stats, update the amount of
+	 * data sent downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 5febd154b6b..9edaece0282 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -4421,7 +4420,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index f4c977262c5..4ffcce0eb23 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -450,6 +450,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 										 ALLOCSET_SMALL_SIZES);
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	/* This plugin uses binary protocol. */
 	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
@@ -591,6 +592,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	OutputPluginPrepareWrite(ctx, !send_replication_origin);
 	logicalrep_write_begin(ctx->out, txn);
 	txndata->sent_begin_txn = true;
+	ctx->stats->sentTxns++;
 
 	send_repl_origin(ctx, txn->origin_id, txn->origin_lsn,
 					 send_replication_origin);
@@ -1469,7 +1471,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TupleTableSlot *new_slot = NULL;
 
 	if (!is_publishable_relation(relation))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		return;
+	}
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1487,15 +1492,24 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1505,6 +1519,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
 			}
 			break;
@@ -1560,7 +1575,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		goto cleanup;
+	}
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1688,6 +1706,9 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
 	}
+	else
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
+
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index ee911394a23..59dda2c2bb7 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1572,6 +1572,13 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/*
+	 * If output plugin maintains statistics, update the amount of data sent
+	 * downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + 1; /* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index ccfb11c49bf..ed055324a99 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -96,6 +96,13 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_bytes);
 	REPLSLOT_ACC(total_txns);
 	REPLSLOT_ACC(total_bytes);
+	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
+	if (repSlotStat->plugin_has_stats)
+	{
+		REPLSLOT_ACC(sent_txns);
+		REPLSLOT_ACC(sent_bytes);
+		REPLSLOT_ACC(filtered_bytes);
+	}
 #undef REPLSLOT_ACC
 
 	pgstat_unlock_entry(entry_ref);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 1c12ddbae49..2add51e8f3a 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2100,7 +2100,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 10
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 13
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2129,7 +2129,13 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "plugin_filtered_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "plugin_sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "plugin_sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2154,11 +2160,23 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[6] = Int64GetDatum(slotent->stream_bytes);
 	values[7] = Int64GetDatum(slotent->total_txns);
 	values[8] = Int64GetDatum(slotent->total_bytes);
+	if (slotent->plugin_has_stats)
+	{
+		values[9] = Int64GetDatum(slotent->filtered_bytes);
+		values[10] = Int64GetDatum(slotent->sent_txns);
+		values[11] = Int64GetDatum(slotent->sent_bytes);
+	}
+	else
+	{
+		nulls[9] = true;
+		nulls[10] = true;
+		nulls[11] = true;
+	}
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[9] = true;
+		nulls[12] = true;
 	else
-		values[9] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[12] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 3ee8fed7e53..267406ae906 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5675,9 +5675,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 202bd2d5ace..9779e5dc5a8 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -395,6 +395,10 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_bytes;
 	PgStat_Counter total_txns;
 	PgStat_Counter total_bytes;
+	bool		plugin_has_stats;
+	PgStat_Counter sent_txns;
+	PgStat_Counter sent_bytes;
+	PgStat_Counter filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 2e562bee5a9..010c59f783d 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -52,6 +52,7 @@ typedef struct LogicalDecodingContext
 
 	OutputPluginCallbacks callbacks;
 	OutputPluginOptions options;
+	OutputPluginStats *stats;
 
 	/*
 	 * User specified options
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..02018f0593c 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -29,6 +29,19 @@ typedef struct OutputPluginOptions
 	bool		receive_rewrites;
 } OutputPluginOptions;
 
+/*
+ * Statistics about the transactions decoded and sent downstream by the output
+ * plugin.
+ */
+typedef struct OutputPluginStats
+{
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data from reoder buffer that was
+								 * filtered out by the output plugin */
+} OutputPluginStats;
+
 /*
  * Type of the shared library symbol _PG_output_plugin_init that is looked up
  * when loading an output plugin shared library.
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index fa0745552f8..3ea2d9885b6 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -715,6 +715,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index 2137c4e5e30..b04a0d9f8db 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -212,10 +212,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -233,10 +233,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index dce8c672b40..acf3c4e4294 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2127,6 +2127,7 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
@@ -2135,9 +2136,12 @@ pg_stat_replication_slots| SELECT s.slot_name,
     s.stream_bytes,
     s.total_txns,
     s.total_bytes,
+    s.plugin_filtered_bytes,
+    s.plugin_sent_txns,
+    s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index a8656419cb6..45da79caead 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1830,6 +1830,7 @@ OuterJoinClauseInfo
 OutputPluginCallbacks
 OutputPluginOptions
 OutputPluginOutputType
+OutputPluginStats
 OverridingKind
 PACE_HEADER
 PACL

base-commit: df335618ed87eecdef44a95e453e345a55a14ad8
-- 
2.34.1

From 9d80a42c1932acff63357148a830df7ada8dfaca Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH 1/2] Report output plugin statistics in
 pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output plugin statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- plugin_filtered_bytes is the amount of changes filtered out by the
  output plugin
- plugin_sent_txns is the amount of transactions sent downstream by the
  output plugin
- plugin_sent_bytes is the amount of data sent downstream by the output
  plugin.

The prefix "plugin_" indicates that these counters are related to and
maintained by the output plugin. An output plugin may choose not to
initialize LogicalDecodingContext::stats, which holds these counters, in
which case the above columns will be reported as NULL.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Additionally report name of the output plugin in the view for an easy
reference.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Author: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++++---------
 contrib/test_decoding/sql/stats.sql           | 15 ++--
 contrib/test_decoding/t/001_repl_stats.pl     | 18 +++--
 contrib/test_decoding/test_decoding.c         |  2 +
 doc/src/sgml/logicaldecoding.sgml             | 27 +++++++
 doc/src/sgml/monitoring.sgml                  | 58 ++++++++++++++
 src/backend/catalog/system_views.sql          |  4 +
 src/backend/replication/logical/logical.c     | 24 +++++-
 .../replication/logical/logicalfuncs.c        |  7 ++
 .../replication/logical/reorderbuffer.c       |  3 +-
 src/backend/replication/pgoutput/pgoutput.c   | 21 +++++
 src/backend/replication/walsender.c           |  7 ++
 src/backend/utils/activity/pgstat_replslot.c  |  7 ++
 src/backend/utils/adt/pgstatfuncs.c           | 26 ++++++-
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  4 +
 src/include/replication/logical.h             |  1 +
 src/include/replication/output_plugin.h       | 13 ++++
 src/include/replication/reorderbuffer.h       |  1 +
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 src/test/regress/expected/rules.out           |  6 +-
 src/tools/pgindent/typedefs.list              |  1 +
 22 files changed, 275 insertions(+), 65 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index de6dc416130..d19fe6a1c61 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | t          | t
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+-- total_txns may vary based on the background activity but sent_txns should
+-- always be 1 since the background transactions are always skipped. Filtered
+-- bytes would be set only when there's a change that was passed to the plugin
+-- but was filtered out. Depending upon the background transactions, filtered
+-- bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_txns | total_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+------------+-------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | t          | t           |                1 | t          | t
+ regression_slot_stats2 | t          | t           | t          | t           |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t          | t           |                1 | t          | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_txns | total_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+------------+-------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | f          | f           |                  |            | 
+ regression_slot_stats2 | t          | t           | t          | t           |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t          | t           |                1 | t          | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | f          | f
- regression_slot_stats3 | t          | t           | f          | f
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_txns | total_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes 
+------------------------+------------+-------------+------------+-------------+------------------+-------------------+-----------------------
+ regression_slot_stats1 | t          | t           | f          | f           |                  |                   |                      
+ regression_slot_stats2 | t          | t           | f          | f           |                  |                   |                      
+ regression_slot_stats3 | t          | t           | f          | f           |                  |                   |                      
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index a022fe1bf07..1077cea5855 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,21 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+-- total_txns may vary based on the background activity but sent_txns should
+-- always be 1 since the background transactions are always skipped. Filtered
+-- bytes would be set only when there's a change that was passed to the plugin
+-- but was filtered out. Depending upon the background transactions, filtered
+-- bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +51,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..76dd86fc420 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, plugin_filtered_bytes may be greater than 0. But it's not
+	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
 		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+			   total_bytes > 0 AS total_bytes,
+			   plugin_sent_txns > 0 AS sent_txn,
+			   plugin_sent_bytes > 0 AS sent_bytes,
+			   plugin_filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index f671a7d4b31..ea5c527644b 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -173,6 +173,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	data->only_local = false;
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
 	opt->receive_rewrites = false;
@@ -310,6 +311,7 @@ static void
 pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
 {
 	OutputPluginPrepareWrite(ctx, last_write);
+	ctx->stats->sentTxns++;
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
 	else
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index b803a819cf1..8ac10cda90c 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -938,6 +938,33 @@ typedef struct OutputPluginOptions
       needs to have a state, it can
       use <literal>ctx-&gt;output_plugin_private</literal> to store it.
      </para>
+
+     <para>
+      The startup callback may initialize <literal>ctx-&gt;stats</literal>,
+      typically as follows, if it chooses to maintain and report statistics
+      about its activity in <structname>pg_stat_replication_slots</structname>.
+<programlisting>
+ctx->stats = palloc0(sizeof(OutputPluginStats));
+</programlisting>
+      where <literal>OutputPluginStats</literal> is defined as follows:
+<programlisting>
+typedef struct OutputPluginStats
+{
+      int64   sentTxns;
+      int64   sentBytes;
+      int64   filteredBytes;
+} OutputPluginStats;
+</programlisting>
+      <literal>sentTxns</literal> is the number of transactions sent downstream
+      by the output plugin. <literal>sentBytes</literal> is the amount of data
+      sent downstream by the output plugin.
+      <function>OutputPluginWrite</function> is expected to update this counter
+      if <literal>ctx-&gt;stats</literal> is initialized by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes in bytes that are
+      filtered out by the output plugin. Function
+      <literal>ReorderBufferChangeSize</literal> may be used to find the size of
+      filtered <literal>ReorderBufferChange</literal>.
+     </para>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..e121f55c9c2 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1545,6 +1545,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1644,6 +1655,53 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is handed over to
+        the output plugin, e.g. the changes filtered by origin. The count is
+        maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>. It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transctions sent to
+        the decoding plugin. Hence this count is expected to be lesser than or
+        equal to <structfield>total_txns</structfield>.  The count is maintained
+        by the output plugin mentioned in <structfield>plugin</structfield>.  It
+        is NULL when statistics is not initialized or immediately after a reset or
+        when not maintained by the output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes sent downstream for this slot by the
+        output plugin after applying filtering and converting into its output
+        format. The count is maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>.  It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index c77fa0234bb..d38c21150b0 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1053,6 +1053,7 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
@@ -1061,6 +1062,9 @@ CREATE VIEW pg_stat_replication_slots AS
             s.stream_bytes,
             s.total_txns,
             s.total_bytes,
+            s.plugin_filtered_bytes,
+            s.plugin_sent_txns,
+            s.plugin_sent_bytes,
             s.stats_reset
     FROM pg_replication_slots as r,
         LATERAL pg_stat_get_replication_slot(slot_name) as s
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index c68c0481f42..b26ac29e32f 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1952,13 +1952,14 @@ void
 UpdateDecodingStats(LogicalDecodingContext *ctx)
 {
 	ReorderBuffer *rb = ctx->reorder;
+	OutputPluginStats *stats = ctx->stats;
 	PgStat_StatReplSlotEntry repSlotStat;
 
 	/* Nothing to do if we don't have any replication stats to be sent. */
 	if (rb->spillBytes <= 0 && rb->streamBytes <= 0 && rb->totalBytes <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " (%s) %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1967,7 +1968,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamCount,
 		 rb->streamBytes,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 stats ? "plugin has stats" : "plugin has no stats",
+		 stats ? stats->sentTxns : 0,
+		 stats ? stats->sentBytes : 0,
+		 stats ? stats->filteredBytes : 0);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1977,6 +1982,15 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_bytes = rb->streamBytes;
 	repSlotStat.total_txns = rb->totalTxns;
 	repSlotStat.total_bytes = rb->totalBytes;
+	if (stats)
+	{
+		repSlotStat.plugin_has_stats = true;
+		repSlotStat.sent_txns = stats->sentTxns;
+		repSlotStat.sent_bytes = stats->sentBytes;
+		repSlotStat.filtered_bytes = stats->filteredBytes;
+	}
+	else
+		repSlotStat.plugin_has_stats = false;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1988,6 +2002,12 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->streamBytes = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	if (stats)
+	{
+		stats->sentTxns = 0;
+		stats->sentBytes = 0;
+		stats->filteredBytes = 0;
+	}
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 25f890ddeed..788967e2ab1 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -89,6 +89,13 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/*
+	 * If output plugin has chosen to maintain its stats, update the amount of
+	 * data sent downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 4736f993c37..12579dff2c1 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -4436,7 +4435,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 80540c017bd..339babbeb56 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -450,6 +450,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 										 ALLOCSET_SMALL_SIZES);
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	/* This plugin uses binary protocol. */
 	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
@@ -591,6 +592,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	OutputPluginPrepareWrite(ctx, !send_replication_origin);
 	logicalrep_write_begin(ctx->out, txn);
 	txndata->sent_begin_txn = true;
+	ctx->stats->sentTxns++;
 
 	send_repl_origin(ctx, txn->origin_id, txn->origin_lsn,
 					 send_replication_origin);
@@ -1469,7 +1471,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TupleTableSlot *new_slot = NULL;
 
 	if (!is_publishable_relation(relation))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		return;
+	}
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1487,15 +1492,24 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1505,6 +1519,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
 			}
 			break;
@@ -1560,7 +1575,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		goto cleanup;
+	}
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1688,6 +1706,9 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
 	}
+	else
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
+
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 59822f22b8d..d9217ce49aa 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1573,6 +1573,13 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/*
+	 * If output plugin maintains statistics, update the amount of data sent
+	 * downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + 1; /* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index ccfb11c49bf..ed055324a99 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -96,6 +96,13 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_bytes);
 	REPLSLOT_ACC(total_txns);
 	REPLSLOT_ACC(total_bytes);
+	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
+	if (repSlotStat->plugin_has_stats)
+	{
+		REPLSLOT_ACC(sent_txns);
+		REPLSLOT_ACC(sent_bytes);
+		REPLSLOT_ACC(filtered_bytes);
+	}
 #undef REPLSLOT_ACC
 
 	pgstat_unlock_entry(entry_ref);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..796dacddcfb 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2100,7 +2100,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 10
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 13
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2129,7 +2129,13 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "plugin_filtered_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "plugin_sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "plugin_sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2154,11 +2160,23 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[6] = Int64GetDatum(slotent->stream_bytes);
 	values[7] = Int64GetDatum(slotent->total_txns);
 	values[8] = Int64GetDatum(slotent->total_bytes);
+	if (slotent->plugin_has_stats)
+	{
+		values[9] = Int64GetDatum(slotent->filtered_bytes);
+		values[10] = Int64GetDatum(slotent->sent_txns);
+		values[11] = Int64GetDatum(slotent->sent_bytes);
+	}
+	else
+	{
+		nulls[9] = true;
+		nulls[10] = true;
+		nulls[11] = true;
+	}
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[9] = true;
+		nulls[12] = true;
 	else
-		values[9] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[12] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 01eba3b5a19..7519941bcf3 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5687,9 +5687,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index f402b17295c..87afeaed8a5 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -395,6 +395,10 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_bytes;
 	PgStat_Counter total_txns;
 	PgStat_Counter total_bytes;
+	bool		plugin_has_stats;
+	PgStat_Counter sent_txns;
+	PgStat_Counter sent_bytes;
+	PgStat_Counter filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 2e562bee5a9..010c59f783d 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -52,6 +52,7 @@ typedef struct LogicalDecodingContext
 
 	OutputPluginCallbacks callbacks;
 	OutputPluginOptions options;
+	OutputPluginStats *stats;
 
 	/*
 	 * User specified options
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..02018f0593c 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -29,6 +29,19 @@ typedef struct OutputPluginOptions
 	bool		receive_rewrites;
 } OutputPluginOptions;
 
+/*
+ * Statistics about the transactions decoded and sent downstream by the output
+ * plugin.
+ */
+typedef struct OutputPluginStats
+{
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data from reoder buffer that was
+								 * filtered out by the output plugin */
+} OutputPluginStats;
+
 /*
  * Type of the shared library symbol _PG_output_plugin_init that is looked up
  * when loading an output plugin shared library.
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index fa0745552f8..3ea2d9885b6 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -715,6 +715,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index 2137c4e5e30..b04a0d9f8db 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -212,10 +212,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -233,10 +233,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..2a048af3569 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2132,6 +2132,7 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
@@ -2140,9 +2141,12 @@ pg_stat_replication_slots| SELECT s.slot_name,
     s.stream_bytes,
     s.total_txns,
     s.total_bytes,
+    s.plugin_filtered_bytes,
+    s.plugin_sent_txns,
+    s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index e90af5b2ad3..8f6af48b04a 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1830,6 +1830,7 @@ OuterJoinClauseInfo
 OutputPluginCallbacks
 OutputPluginOptions
 OutputPluginOutputType
+OutputPluginStats
 OverridingKind
 PACE_HEADER
 PACL

base-commit: 18cdf5932a279a2c035d44460e1e0cbb659471f2
-- 
2.34.1

From e2500f1c610d2f73b53e353b98856a90db4cc452 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Thu, 18 Sep 2025 15:55:01 +0530
Subject: [PATCH 2/2] Address review comments

Among others rename total_txns and total_bytes to total_wal_txns and
total_wal_bytes respectively.

Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Shveta Malik <shveta.malik@gmail.com>
---
 contrib/test_decoding/expected/stats.out  | 58 +++++++++++------------
 contrib/test_decoding/sql/stats.sql       | 17 +++----
 contrib/test_decoding/t/001_repl_stats.pl |  6 +--
 doc/src/sgml/logicaldecoding.sgml         |  6 +--
 doc/src/sgml/monitoring.sgml              | 18 +++----
 src/backend/catalog/system_views.sql      |  4 +-
 src/backend/utils/adt/pgstatfuncs.c       |  4 +-
 src/include/catalog/pg_proc.dat           |  2 +-
 src/test/regress/expected/rules.out       |  6 +--
 9 files changed, 61 insertions(+), 60 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index d19fe6a1c61..4834b3460a6 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,17 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
--- total_txns may vary based on the background activity but sent_txns should
--- always be 1 since the background transactions are always skipped. Filtered
--- bytes would be set only when there's a change that was passed to the plugin
--- but was filtered out. Depending upon the background transactions, filtered
--- bytes may or may not be zero.
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
-------------------------+------------+-------------+------------+-------------+------------------+------------+----------------
- regression_slot_stats1 | t          | t           | t          | t           |                1 | t          | t
- regression_slot_stats2 | t          | t           | t          | t           |                1 | t          | t
- regression_slot_stats3 | t          | t           | t          | t           |                1 | t          | t
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -58,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
-------------------------+------------+-------------+------------+-------------+------------------+------------+----------------
- regression_slot_stats1 | t          | t           | f          | f           |                  |            | 
- regression_slot_stats2 | t          | t           | t          | t           |                1 | t          | t
- regression_slot_stats3 | t          | t           | t          | t           |                1 | t          | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |            | 
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 -- reset stats for all slots
@@ -73,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes 
-------------------------+------------+-------------+------------+-------------+------------------+-------------------+-----------------------
- regression_slot_stats1 | t          | t           | f          | f           |                  |                   |                      
- regression_slot_stats2 | t          | t           | f          | f           |                  |                   |                      
- regression_slot_stats3 | t          | t           | f          | f           |                  |                   |                      
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+-------------------+-----------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats2 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats3 | t          | t           | f              | f               |                  |                   |                      
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-----------------------+------------------+-------------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 |                       |                  |                   | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-----------------------+------------------+-------------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 |                       |                  |                   | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index 1077cea5855..99f513902d3 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,21 +15,22 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
--- total_txns may vary based on the background activity but sent_txns should
--- always be 1 since the background transactions are always skipped. Filtered
--- bytes would be set only when there's a change that was passed to the plugin
--- but was filtered out. Depending upon the background transactions, filtered
--- bytes may or may not be zero.
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 76dd86fc420..756fc691ed6 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -28,8 +28,8 @@ sub test_slot_stats
 	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
-		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes,
+		SELECT slot_name, total_wal_txns > 0 AS total_txn,
+			   total_wal_bytes > 0 AS total_bytes,
 			   plugin_sent_txns > 0 AS sent_txn,
 			   plugin_sent_bytes > 0 AS sent_bytes,
 			   plugin_filtered_bytes >= 0 AS filtered_bytes
@@ -71,7 +71,7 @@ $node->poll_query_until(
 	'postgres', qq[
 	SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
 	WHERE slot_name ~ 'regression_slot'
-	AND total_txns > 0 AND total_bytes > 0;
+	AND total_wal_txns > 0 AND total_wal_bytes > 0;
 ]) or die "Timed out while waiting for statistics to be updated";
 
 # Test to drop one of the replication slot and verify replication statistics data is
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index 8ac10cda90c..3952f68e806 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -956,11 +956,11 @@ typedef struct OutputPluginStats
 } OutputPluginStats;
 </programlisting>
       <literal>sentTxns</literal> is the number of transactions sent downstream
-      by the output plugin. <literal>sentBytes</literal> is the amount of data
+      by the output plugin. <literal>sentBytes</literal> is the amount of data, in bytes,
       sent downstream by the output plugin.
-      <function>OutputPluginWrite</function> is expected to update this counter
+      <function>OutputPluginWrite</function> will update this counter
       if <literal>ctx-&gt;stats</literal> is initialized by the output plugin.
-      <literal>filteredBytes</literal> is the size of changes in bytes that are
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that are
       filtered out by the output plugin. Function
       <literal>ReorderBufferChangeSize</literal> may be used to find the size of
       filtered <literal>ReorderBufferChange</literal>.
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index e121f55c9c2..fbe03ffd670 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1633,19 +1633,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_txns</structfield> <type>bigint</type>
+        <structfield>total_wal_txns</structfield> <type>bigint</type>
        </para>
        <para>
-        Number of decoded transactions sent to the decoding output plugin for
-        this slot. This counts top-level transactions only, and is not incremented
-        for subtransactions. Note that this includes the transactions that are
-        streamed and/or spilled.
+        Number of decoded transactions from WAL sent to the decoding output
+        plugin for this slot. This counts top-level transactions only, and is
+        not incremented for subtransactions. Note that this includes the
+        transactions that are streamed and/or spilled.
        </para></entry>
      </row>
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_bytes</structfield><type>bigint</type>
+        <structfield>total_wal_bytes</structfield><type>bigint</type>
        </para>
        <para>
         Amount of transaction data decoded for sending transactions to the
@@ -1660,9 +1660,9 @@ description | Waiting for a newly initialized WAL file to reach durable storage
         <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
        </para>
        <para>
-        Amount of changes, from <structfield>total_bytes</structfield>, filtered
+        Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
         out by the output plugin and not sent downstream. Please note that it
-        does not include the changes filtered before a change is handed over to
+        does not include the changes filtered before a change is sent to
         the output plugin, e.g. the changes filtered by origin. The count is
         maintained by the output plugin mentioned in
         <structfield>plugin</structfield>. It is NULL when statistics is not
@@ -1680,7 +1680,7 @@ description | Waiting for a newly initialized WAL file to reach durable storage
         counts top-level transactions only, and is not incremented for
         subtransactions. These transactions are subset of transctions sent to
         the decoding plugin. Hence this count is expected to be lesser than or
-        equal to <structfield>total_txns</structfield>.  The count is maintained
+        equal to <structfield>total_wal_txns</structfield>.  The count is maintained
         by the output plugin mentioned in <structfield>plugin</structfield>.  It
         is NULL when statistics is not initialized or immediately after a reset or
         when not maintained by the output plugin.
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index d38c21150b0..9e8e32b5849 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1060,8 +1060,8 @@ CREATE VIEW pg_stat_replication_slots AS
             s.stream_txns,
             s.stream_count,
             s.stream_bytes,
-            s.total_txns,
-            s.total_bytes,
+            s.total_wal_txns,
+            s.total_wal_bytes,
             s.plugin_filtered_bytes,
             s.plugin_sent_txns,
             s.plugin_sent_bytes,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 796dacddcfb..15bafe63b24 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2125,9 +2125,9 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "stream_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_txns",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_wal_txns",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_bytes",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_wal_bytes",
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "plugin_filtered_bytes",
 					   INT8OID, -1, 0);
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 7519941bcf3..9e4f6620214 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5689,7 +5689,7 @@
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
   proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
   proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_wal_txns,total_wal_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2a048af3569..2a401552a7a 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2139,14 +2139,14 @@ pg_stat_replication_slots| SELECT s.slot_name,
     s.stream_txns,
     s.stream_count,
     s.stream_bytes,
-    s.total_txns,
-    s.total_bytes,
+    s.total_wal_txns,
+    s.total_wal_bytes,
     s.plugin_filtered_bytes,
     s.plugin_sent_txns,
     s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_wal_txns, total_wal_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
-- 
2.34.1

From a27c83fdf1f49a43844c1c4bcd763439e225f82d Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH 1/2] Report output plugin statistics in
 pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output plugin statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- plugin_filtered_bytes is the amount of changes filtered out by the
  output plugin
- plugin_sent_txns is the amount of transactions sent downstream by the
  output plugin
- plugin_sent_bytes is the amount of data sent downstream by the output
  plugin.

The prefix "plugin_" indicates that these counters are related to and
maintained by the output plugin. An output plugin may choose not to
initialize LogicalDecodingContext::stats, which holds these counters, in
which case the above columns will be reported as NULL.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Additionally report name of the output plugin in the view for an easy
reference.

total_bytes and total_txns are the only fields remaining unqualified -
they do not convey what those bytes and txns are. Hence rename them
total_wal_bytes and total_wal_txns respectively to indicate that those
counts come from WAL stream.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Shveta Malik <shveta.malik@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++++---------
 contrib/test_decoding/sql/stats.sql           | 16 ++--
 contrib/test_decoding/t/001_repl_stats.pl     | 22 ++++--
 contrib/test_decoding/test_decoding.c         |  2 +
 doc/src/sgml/logicaldecoding.sgml             | 27 +++++++
 doc/src/sgml/monitoring.sgml                  | 70 +++++++++++++++--
 src/backend/catalog/system_views.sql          |  8 +-
 src/backend/replication/logical/logical.c     | 24 +++++-
 .../replication/logical/logicalfuncs.c        |  7 ++
 .../replication/logical/reorderbuffer.c       |  3 +-
 src/backend/replication/pgoutput/pgoutput.c   | 21 +++++
 src/backend/replication/walsender.c           |  7 ++
 src/backend/utils/activity/pgstat_replslot.c  |  7 ++
 src/backend/utils/adt/pgstatfuncs.c           | 30 ++++++--
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  4 +
 src/include/replication/logical.h             |  1 +
 src/include/replication/output_plugin.h       | 13 ++++
 src/include/replication/reorderbuffer.h       |  1 +
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 src/test/regress/expected/rules.out           | 10 ++-
 src/tools/pgindent/typedefs.list              |  1 +
 22 files changed, 290 insertions(+), 79 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index de6dc416130..4834b3460a6 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | t          | t
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |            | 
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | f          | f
- regression_slot_stats3 | t          | t           | f          | f
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+-------------------+-----------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats2 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats3 | t          | t           | f              | f               |                  |                   |                      
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index a022fe1bf07..99f513902d3 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,22 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +52,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..756fc691ed6 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, plugin_filtered_bytes may be greater than 0. But it's not
+	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
-		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+		SELECT slot_name, total_wal_txns > 0 AS total_txn,
+			   total_wal_bytes > 0 AS total_bytes,
+			   plugin_sent_txns > 0 AS sent_txn,
+			   plugin_sent_bytes > 0 AS sent_bytes,
+			   plugin_filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -65,7 +71,7 @@ $node->poll_query_until(
 	'postgres', qq[
 	SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
 	WHERE slot_name ~ 'regression_slot'
-	AND total_txns > 0 AND total_bytes > 0;
+	AND total_wal_txns > 0 AND total_wal_bytes > 0;
 ]) or die "Timed out while waiting for statistics to be updated";
 
 # Test to drop one of the replication slot and verify replication statistics data is
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index f671a7d4b31..ea5c527644b 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -173,6 +173,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	data->only_local = false;
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
 	opt->receive_rewrites = false;
@@ -310,6 +311,7 @@ static void
 pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
 {
 	OutputPluginPrepareWrite(ctx, last_write);
+	ctx->stats->sentTxns++;
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
 	else
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index b803a819cf1..3952f68e806 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -938,6 +938,33 @@ typedef struct OutputPluginOptions
       needs to have a state, it can
       use <literal>ctx-&gt;output_plugin_private</literal> to store it.
      </para>
+
+     <para>
+      The startup callback may initialize <literal>ctx-&gt;stats</literal>,
+      typically as follows, if it chooses to maintain and report statistics
+      about its activity in <structname>pg_stat_replication_slots</structname>.
+<programlisting>
+ctx->stats = palloc0(sizeof(OutputPluginStats));
+</programlisting>
+      where <literal>OutputPluginStats</literal> is defined as follows:
+<programlisting>
+typedef struct OutputPluginStats
+{
+      int64   sentTxns;
+      int64   sentBytes;
+      int64   filteredBytes;
+} OutputPluginStats;
+</programlisting>
+      <literal>sentTxns</literal> is the number of transactions sent downstream
+      by the output plugin. <literal>sentBytes</literal> is the amount of data, in bytes,
+      sent downstream by the output plugin.
+      <function>OutputPluginWrite</function> will update this counter
+      if <literal>ctx-&gt;stats</literal> is initialized by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that are
+      filtered out by the output plugin. Function
+      <literal>ReorderBufferChangeSize</literal> may be used to find the size of
+      filtered <literal>ReorderBufferChange</literal>.
+     </para>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..fbe03ffd670 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1545,6 +1545,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1622,19 +1633,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_txns</structfield> <type>bigint</type>
+        <structfield>total_wal_txns</structfield> <type>bigint</type>
        </para>
        <para>
-        Number of decoded transactions sent to the decoding output plugin for
-        this slot. This counts top-level transactions only, and is not incremented
-        for subtransactions. Note that this includes the transactions that are
-        streamed and/or spilled.
+        Number of decoded transactions from WAL sent to the decoding output
+        plugin for this slot. This counts top-level transactions only, and is
+        not incremented for subtransactions. Note that this includes the
+        transactions that are streamed and/or spilled.
        </para></entry>
      </row>
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_bytes</structfield><type>bigint</type>
+        <structfield>total_wal_bytes</structfield><type>bigint</type>
        </para>
        <para>
         Amount of transaction data decoded for sending transactions to the
@@ -1644,6 +1655,53 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is sent to
+        the output plugin, e.g. the changes filtered by origin. The count is
+        maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>. It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transctions sent to
+        the decoding plugin. Hence this count is expected to be lesser than or
+        equal to <structfield>total_wal_txns</structfield>.  The count is maintained
+        by the output plugin mentioned in <structfield>plugin</structfield>.  It
+        is NULL when statistics is not initialized or immediately after a reset or
+        when not maintained by the output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes sent downstream for this slot by the
+        output plugin after applying filtering and converting into its output
+        format. The count is maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>.  It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index c77fa0234bb..9e8e32b5849 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1053,14 +1053,18 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
             s.stream_txns,
             s.stream_count,
             s.stream_bytes,
-            s.total_txns,
-            s.total_bytes,
+            s.total_wal_txns,
+            s.total_wal_bytes,
+            s.plugin_filtered_bytes,
+            s.plugin_sent_txns,
+            s.plugin_sent_bytes,
             s.stats_reset
     FROM pg_replication_slots as r,
         LATERAL pg_stat_get_replication_slot(slot_name) as s
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index c68c0481f42..b26ac29e32f 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1952,13 +1952,14 @@ void
 UpdateDecodingStats(LogicalDecodingContext *ctx)
 {
 	ReorderBuffer *rb = ctx->reorder;
+	OutputPluginStats *stats = ctx->stats;
 	PgStat_StatReplSlotEntry repSlotStat;
 
 	/* Nothing to do if we don't have any replication stats to be sent. */
 	if (rb->spillBytes <= 0 && rb->streamBytes <= 0 && rb->totalBytes <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " (%s) %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1967,7 +1968,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamCount,
 		 rb->streamBytes,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 stats ? "plugin has stats" : "plugin has no stats",
+		 stats ? stats->sentTxns : 0,
+		 stats ? stats->sentBytes : 0,
+		 stats ? stats->filteredBytes : 0);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1977,6 +1982,15 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_bytes = rb->streamBytes;
 	repSlotStat.total_txns = rb->totalTxns;
 	repSlotStat.total_bytes = rb->totalBytes;
+	if (stats)
+	{
+		repSlotStat.plugin_has_stats = true;
+		repSlotStat.sent_txns = stats->sentTxns;
+		repSlotStat.sent_bytes = stats->sentBytes;
+		repSlotStat.filtered_bytes = stats->filteredBytes;
+	}
+	else
+		repSlotStat.plugin_has_stats = false;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1988,6 +2002,12 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->streamBytes = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	if (stats)
+	{
+		stats->sentTxns = 0;
+		stats->sentBytes = 0;
+		stats->filteredBytes = 0;
+	}
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 25f890ddeed..788967e2ab1 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -89,6 +89,13 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/*
+	 * If output plugin has chosen to maintain its stats, update the amount of
+	 * data sent downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 4736f993c37..12579dff2c1 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -4436,7 +4435,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 80540c017bd..339babbeb56 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -450,6 +450,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 										 ALLOCSET_SMALL_SIZES);
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	/* This plugin uses binary protocol. */
 	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
@@ -591,6 +592,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	OutputPluginPrepareWrite(ctx, !send_replication_origin);
 	logicalrep_write_begin(ctx->out, txn);
 	txndata->sent_begin_txn = true;
+	ctx->stats->sentTxns++;
 
 	send_repl_origin(ctx, txn->origin_id, txn->origin_lsn,
 					 send_replication_origin);
@@ -1469,7 +1471,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TupleTableSlot *new_slot = NULL;
 
 	if (!is_publishable_relation(relation))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		return;
+	}
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1487,15 +1492,24 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1505,6 +1519,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
 			}
 			break;
@@ -1560,7 +1575,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		goto cleanup;
+	}
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1688,6 +1706,9 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
 	}
+	else
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
+
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 59822f22b8d..d9217ce49aa 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1573,6 +1573,13 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/*
+	 * If output plugin maintains statistics, update the amount of data sent
+	 * downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + 1; /* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index ccfb11c49bf..ed055324a99 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -96,6 +96,13 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_bytes);
 	REPLSLOT_ACC(total_txns);
 	REPLSLOT_ACC(total_bytes);
+	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
+	if (repSlotStat->plugin_has_stats)
+	{
+		REPLSLOT_ACC(sent_txns);
+		REPLSLOT_ACC(sent_bytes);
+		REPLSLOT_ACC(filtered_bytes);
+	}
 #undef REPLSLOT_ACC
 
 	pgstat_unlock_entry(entry_ref);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..15bafe63b24 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2100,7 +2100,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 10
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 13
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2125,11 +2125,17 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "stream_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_txns",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_wal_txns",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_bytes",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_wal_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "plugin_filtered_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "plugin_sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "plugin_sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2154,11 +2160,23 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[6] = Int64GetDatum(slotent->stream_bytes);
 	values[7] = Int64GetDatum(slotent->total_txns);
 	values[8] = Int64GetDatum(slotent->total_bytes);
+	if (slotent->plugin_has_stats)
+	{
+		values[9] = Int64GetDatum(slotent->filtered_bytes);
+		values[10] = Int64GetDatum(slotent->sent_txns);
+		values[11] = Int64GetDatum(slotent->sent_bytes);
+	}
+	else
+	{
+		nulls[9] = true;
+		nulls[10] = true;
+		nulls[11] = true;
+	}
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[9] = true;
+		nulls[12] = true;
 	else
-		values[9] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[12] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 01eba3b5a19..9e4f6620214 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5687,9 +5687,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_wal_txns,total_wal_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index f402b17295c..87afeaed8a5 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -395,6 +395,10 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_bytes;
 	PgStat_Counter total_txns;
 	PgStat_Counter total_bytes;
+	bool		plugin_has_stats;
+	PgStat_Counter sent_txns;
+	PgStat_Counter sent_bytes;
+	PgStat_Counter filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 2e562bee5a9..010c59f783d 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -52,6 +52,7 @@ typedef struct LogicalDecodingContext
 
 	OutputPluginCallbacks callbacks;
 	OutputPluginOptions options;
+	OutputPluginStats *stats;
 
 	/*
 	 * User specified options
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..02018f0593c 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -29,6 +29,19 @@ typedef struct OutputPluginOptions
 	bool		receive_rewrites;
 } OutputPluginOptions;
 
+/*
+ * Statistics about the transactions decoded and sent downstream by the output
+ * plugin.
+ */
+typedef struct OutputPluginStats
+{
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data from reoder buffer that was
+								 * filtered out by the output plugin */
+} OutputPluginStats;
+
 /*
  * Type of the shared library symbol _PG_output_plugin_init that is looked up
  * when loading an output plugin shared library.
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index fa0745552f8..3ea2d9885b6 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -715,6 +715,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index 2137c4e5e30..b04a0d9f8db 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -212,10 +212,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -233,10 +233,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..2a401552a7a 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2132,17 +2132,21 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
     s.stream_txns,
     s.stream_count,
     s.stream_bytes,
-    s.total_txns,
-    s.total_bytes,
+    s.total_wal_txns,
+    s.total_wal_bytes,
+    s.plugin_filtered_bytes,
+    s.plugin_sent_txns,
+    s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_wal_txns, total_wal_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 3c80d49b67e..b97915c1697 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1830,6 +1830,7 @@ OuterJoinClauseInfo
 OutputPluginCallbacks
 OutputPluginOptions
 OutputPluginOutputType
+OutputPluginStats
 OverridingKind
 PACE_HEADER
 PACL

base-commit: 5334620eef8f7b429594e6cf9dc97331eda2a8bd
-- 
2.34.1

From 3db9ce87b46783f20e8c34958f7cc2903bddd7da Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Tue, 23 Sep 2025 16:43:33 +0530
Subject: [PATCH 2/2] Address second round of comments from Shveta Malik

Add a test for plugin_filtered_bytes in logical replication case. We can
not test exact number of bytes filtered because of the unavoidable
background transaction activity which will be counted in the filtered
bytes.
---
 doc/src/sgml/logicaldecoding.sgml                  | 13 +++++++------
 src/backend/replication/logical/logical.c          | 10 +++++-----
 src/backend/replication/logical/logicalfuncs.c     |  1 +
 src/backend/utils/activity/pgstat_replslot.c       | 10 +++++-----
 src/backend/utils/adt/pgstatfuncs.c                | 10 +++++-----
 src/include/pgstat.h                               | 10 +++++-----
 src/test/recovery/t/006_logical_decoding.pl        |  6 +++---
 .../recovery/t/035_standby_logical_decoding.pl     |  4 ++--
 src/test/subscription/t/028_row_filter.pl          | 14 ++++++++++++++
 9 files changed, 47 insertions(+), 31 deletions(-)

diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index 3952f68e806..c02d4a88d57 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -956,12 +956,13 @@ typedef struct OutputPluginStats
 } OutputPluginStats;
 </programlisting>
       <literal>sentTxns</literal> is the number of transactions sent downstream
-      by the output plugin. <literal>sentBytes</literal> is the amount of data, in bytes,
-      sent downstream by the output plugin.
-      <function>OutputPluginWrite</function> will update this counter
-      if <literal>ctx-&gt;stats</literal> is initialized by the output plugin.
-      <literal>filteredBytes</literal> is the size of changes, in bytes, that are
-      filtered out by the output plugin. Function
+      by the output plugin. <literal>sentBytes</literal> is the amount of data,
+      in bytes, sent downstream by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that
+      are filtered out by the output plugin.
+      <function>OutputPluginWrite</function> will update
+      <literal>sentBytes</literal> if <literal>ctx-&gt;stats</literal> is
+      initialized by the output plugin. Function
       <literal>ReorderBufferChangeSize</literal> may be used to find the size of
       filtered <literal>ReorderBufferChange</literal>.
      </para>
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index b26ac29e32f..1435873101f 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1980,14 +1980,14 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_txns = rb->streamTxns;
 	repSlotStat.stream_count = rb->streamCount;
 	repSlotStat.stream_bytes = rb->streamBytes;
-	repSlotStat.total_txns = rb->totalTxns;
-	repSlotStat.total_bytes = rb->totalBytes;
+	repSlotStat.total_wal_txns = rb->totalTxns;
+	repSlotStat.total_wal_bytes = rb->totalBytes;
 	if (stats)
 	{
 		repSlotStat.plugin_has_stats = true;
-		repSlotStat.sent_txns = stats->sentTxns;
-		repSlotStat.sent_bytes = stats->sentBytes;
-		repSlotStat.filtered_bytes = stats->filteredBytes;
+		repSlotStat.plugin_sent_txns = stats->sentTxns;
+		repSlotStat.plugin_sent_bytes = stats->sentBytes;
+		repSlotStat.plugin_filtered_bytes = stats->filteredBytes;
 	}
 	else
 		repSlotStat.plugin_has_stats = false;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 788967e2ab1..d2ab41de438 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -96,6 +96,7 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	 */
 	if (ctx->stats)
 		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
+
 	p->returned_rows++;
 }
 
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index ed055324a99..895940f4eb9 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -94,14 +94,14 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_txns);
 	REPLSLOT_ACC(stream_count);
 	REPLSLOT_ACC(stream_bytes);
-	REPLSLOT_ACC(total_txns);
-	REPLSLOT_ACC(total_bytes);
+	REPLSLOT_ACC(total_wal_txns);
+	REPLSLOT_ACC(total_wal_bytes);
 	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
 	if (repSlotStat->plugin_has_stats)
 	{
-		REPLSLOT_ACC(sent_txns);
-		REPLSLOT_ACC(sent_bytes);
-		REPLSLOT_ACC(filtered_bytes);
+		REPLSLOT_ACC(plugin_sent_txns);
+		REPLSLOT_ACC(plugin_sent_bytes);
+		REPLSLOT_ACC(plugin_filtered_bytes);
 	}
 #undef REPLSLOT_ACC
 
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 15bafe63b24..588b49059b2 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2158,13 +2158,13 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[4] = Int64GetDatum(slotent->stream_txns);
 	values[5] = Int64GetDatum(slotent->stream_count);
 	values[6] = Int64GetDatum(slotent->stream_bytes);
-	values[7] = Int64GetDatum(slotent->total_txns);
-	values[8] = Int64GetDatum(slotent->total_bytes);
+	values[7] = Int64GetDatum(slotent->total_wal_txns);
+	values[8] = Int64GetDatum(slotent->total_wal_bytes);
 	if (slotent->plugin_has_stats)
 	{
-		values[9] = Int64GetDatum(slotent->filtered_bytes);
-		values[10] = Int64GetDatum(slotent->sent_txns);
-		values[11] = Int64GetDatum(slotent->sent_bytes);
+		values[9] = Int64GetDatum(slotent->plugin_filtered_bytes);
+		values[10] = Int64GetDatum(slotent->plugin_sent_txns);
+		values[11] = Int64GetDatum(slotent->plugin_sent_bytes);
 	}
 	else
 	{
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 87afeaed8a5..33a031c79b4 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -393,12 +393,12 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_txns;
 	PgStat_Counter stream_count;
 	PgStat_Counter stream_bytes;
-	PgStat_Counter total_txns;
-	PgStat_Counter total_bytes;
+	PgStat_Counter total_wal_txns;
+	PgStat_Counter total_wal_bytes;
 	bool		plugin_has_stats;
-	PgStat_Counter sent_txns;
-	PgStat_Counter sent_bytes;
-	PgStat_Counter filtered_bytes;
+	PgStat_Counter plugin_sent_txns;
+	PgStat_Counter plugin_sent_bytes;
+	PgStat_Counter plugin_filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index b04a0d9f8db..92e42bec6a9 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -212,7 +212,7 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_wal_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
 	qq(t|t|t),
 	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
@@ -233,10 +233,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_wal_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
 	qq(t|t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_wal_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index c9c182892cf..c8577794eec 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -575,7 +575,7 @@ $node_primary->safe_psql('testdb',
 	qq[INSERT INTO decoding_test(x,y) SELECT 100,'100';]);
 
 $node_standby->poll_query_until('testdb',
-	qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+	qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 ) or die "replication slot stats of vacuum_full_activeslot not updated";
 
 # This should trigger the conflict
@@ -603,7 +603,7 @@ ok( $stderr =~
 # Ensure that replication slot stats are not removed after invalidation.
 is( $node_standby->safe_psql(
 		'testdb',
-		qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+		qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 	),
 	't',
 	'replication slot stats not removed after invalidation');
diff --git a/src/test/subscription/t/028_row_filter.pl b/src/test/subscription/t/028_row_filter.pl
index e2c83670053..798364c62e6 100644
--- a/src/test/subscription/t/028_row_filter.pl
+++ b/src/test/subscription/t/028_row_filter.pl
@@ -579,6 +579,11 @@ is($result, qq(3|6),
 # commands are for testing normal logical replication behavior.
 #
 # test row filter (INSERT, UPDATE, DELETE)
+#
+# Get initial plugin statistics before any filtering occurs
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_rowfilter_1 (a, b) VALUES (800, 'test 800')");
 $node_publisher->safe_psql('postgres',
@@ -612,6 +617,15 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup($appname);
 
+# Check final plugin statistics and verify filtering occurred.
+# plugin_filtered_bytes includes the amount of changes from background
+# transactions, which may or may not happen. Hence testing exact amount of
+# filtered data is not possible.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after row filtering');
+
 # Check expected replicated rows for tab_rowfilter_2
 # tap_pub_1 filter is: (c % 2 = 0)
 # tap_pub_2 filter is: (c % 3 = 0)
-- 
2.34.1

From a27c83fdf1f49a43844c1c4bcd763439e225f82d Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH 1/2] Report output plugin statistics in
 pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output plugin statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- plugin_filtered_bytes is the amount of changes filtered out by the
  output plugin
- plugin_sent_txns is the amount of transactions sent downstream by the
  output plugin
- plugin_sent_bytes is the amount of data sent downstream by the output
  plugin.

The prefix "plugin_" indicates that these counters are related to and
maintained by the output plugin. An output plugin may choose not to
initialize LogicalDecodingContext::stats, which holds these counters, in
which case the above columns will be reported as NULL.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Additionally report name of the output plugin in the view for an easy
reference.

total_bytes and total_txns are the only fields remaining unqualified -
they do not convey what those bytes and txns are. Hence rename them
total_wal_bytes and total_wal_txns respectively to indicate that those
counts come from WAL stream.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Shveta Malik <shveta.malik@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++++---------
 contrib/test_decoding/sql/stats.sql           | 16 ++--
 contrib/test_decoding/t/001_repl_stats.pl     | 22 ++++--
 contrib/test_decoding/test_decoding.c         |  2 +
 doc/src/sgml/logicaldecoding.sgml             | 27 +++++++
 doc/src/sgml/monitoring.sgml                  | 70 +++++++++++++++--
 src/backend/catalog/system_views.sql          |  8 +-
 src/backend/replication/logical/logical.c     | 24 +++++-
 .../replication/logical/logicalfuncs.c        |  7 ++
 .../replication/logical/reorderbuffer.c       |  3 +-
 src/backend/replication/pgoutput/pgoutput.c   | 21 +++++
 src/backend/replication/walsender.c           |  7 ++
 src/backend/utils/activity/pgstat_replslot.c  |  7 ++
 src/backend/utils/adt/pgstatfuncs.c           | 30 ++++++--
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  4 +
 src/include/replication/logical.h             |  1 +
 src/include/replication/output_plugin.h       | 13 ++++
 src/include/replication/reorderbuffer.h       |  1 +
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 src/test/regress/expected/rules.out           | 10 ++-
 src/tools/pgindent/typedefs.list              |  1 +
 22 files changed, 290 insertions(+), 79 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index de6dc416130..4834b3460a6 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | t          | t
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |            | 
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | f          | f
- regression_slot_stats3 | t          | t           | f          | f
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+-------------------+-----------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats2 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats3 | t          | t           | f              | f               |                  |                   |                      
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index a022fe1bf07..99f513902d3 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,22 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +52,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..756fc691ed6 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, plugin_filtered_bytes may be greater than 0. But it's not
+	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
-		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+		SELECT slot_name, total_wal_txns > 0 AS total_txn,
+			   total_wal_bytes > 0 AS total_bytes,
+			   plugin_sent_txns > 0 AS sent_txn,
+			   plugin_sent_bytes > 0 AS sent_bytes,
+			   plugin_filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -65,7 +71,7 @@ $node->poll_query_until(
 	'postgres', qq[
 	SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
 	WHERE slot_name ~ 'regression_slot'
-	AND total_txns > 0 AND total_bytes > 0;
+	AND total_wal_txns > 0 AND total_wal_bytes > 0;
 ]) or die "Timed out while waiting for statistics to be updated";
 
 # Test to drop one of the replication slot and verify replication statistics data is
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index f671a7d4b31..ea5c527644b 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -173,6 +173,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	data->only_local = false;
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
 	opt->receive_rewrites = false;
@@ -310,6 +311,7 @@ static void
 pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
 {
 	OutputPluginPrepareWrite(ctx, last_write);
+	ctx->stats->sentTxns++;
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
 	else
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index b803a819cf1..3952f68e806 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -938,6 +938,33 @@ typedef struct OutputPluginOptions
       needs to have a state, it can
       use <literal>ctx-&gt;output_plugin_private</literal> to store it.
      </para>
+
+     <para>
+      The startup callback may initialize <literal>ctx-&gt;stats</literal>,
+      typically as follows, if it chooses to maintain and report statistics
+      about its activity in <structname>pg_stat_replication_slots</structname>.
+<programlisting>
+ctx->stats = palloc0(sizeof(OutputPluginStats));
+</programlisting>
+      where <literal>OutputPluginStats</literal> is defined as follows:
+<programlisting>
+typedef struct OutputPluginStats
+{
+      int64   sentTxns;
+      int64   sentBytes;
+      int64   filteredBytes;
+} OutputPluginStats;
+</programlisting>
+      <literal>sentTxns</literal> is the number of transactions sent downstream
+      by the output plugin. <literal>sentBytes</literal> is the amount of data, in bytes,
+      sent downstream by the output plugin.
+      <function>OutputPluginWrite</function> will update this counter
+      if <literal>ctx-&gt;stats</literal> is initialized by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that are
+      filtered out by the output plugin. Function
+      <literal>ReorderBufferChangeSize</literal> may be used to find the size of
+      filtered <literal>ReorderBufferChange</literal>.
+     </para>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..fbe03ffd670 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1545,6 +1545,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1622,19 +1633,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_txns</structfield> <type>bigint</type>
+        <structfield>total_wal_txns</structfield> <type>bigint</type>
        </para>
        <para>
-        Number of decoded transactions sent to the decoding output plugin for
-        this slot. This counts top-level transactions only, and is not incremented
-        for subtransactions. Note that this includes the transactions that are
-        streamed and/or spilled.
+        Number of decoded transactions from WAL sent to the decoding output
+        plugin for this slot. This counts top-level transactions only, and is
+        not incremented for subtransactions. Note that this includes the
+        transactions that are streamed and/or spilled.
        </para></entry>
      </row>
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_bytes</structfield><type>bigint</type>
+        <structfield>total_wal_bytes</structfield><type>bigint</type>
        </para>
        <para>
         Amount of transaction data decoded for sending transactions to the
@@ -1644,6 +1655,53 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is sent to
+        the output plugin, e.g. the changes filtered by origin. The count is
+        maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>. It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transctions sent to
+        the decoding plugin. Hence this count is expected to be lesser than or
+        equal to <structfield>total_wal_txns</structfield>.  The count is maintained
+        by the output plugin mentioned in <structfield>plugin</structfield>.  It
+        is NULL when statistics is not initialized or immediately after a reset or
+        when not maintained by the output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes sent downstream for this slot by the
+        output plugin after applying filtering and converting into its output
+        format. The count is maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>.  It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index c77fa0234bb..9e8e32b5849 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1053,14 +1053,18 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
             s.stream_txns,
             s.stream_count,
             s.stream_bytes,
-            s.total_txns,
-            s.total_bytes,
+            s.total_wal_txns,
+            s.total_wal_bytes,
+            s.plugin_filtered_bytes,
+            s.plugin_sent_txns,
+            s.plugin_sent_bytes,
             s.stats_reset
     FROM pg_replication_slots as r,
         LATERAL pg_stat_get_replication_slot(slot_name) as s
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index c68c0481f42..b26ac29e32f 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1952,13 +1952,14 @@ void
 UpdateDecodingStats(LogicalDecodingContext *ctx)
 {
 	ReorderBuffer *rb = ctx->reorder;
+	OutputPluginStats *stats = ctx->stats;
 	PgStat_StatReplSlotEntry repSlotStat;
 
 	/* Nothing to do if we don't have any replication stats to be sent. */
 	if (rb->spillBytes <= 0 && rb->streamBytes <= 0 && rb->totalBytes <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " (%s) %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1967,7 +1968,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamCount,
 		 rb->streamBytes,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 stats ? "plugin has stats" : "plugin has no stats",
+		 stats ? stats->sentTxns : 0,
+		 stats ? stats->sentBytes : 0,
+		 stats ? stats->filteredBytes : 0);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1977,6 +1982,15 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_bytes = rb->streamBytes;
 	repSlotStat.total_txns = rb->totalTxns;
 	repSlotStat.total_bytes = rb->totalBytes;
+	if (stats)
+	{
+		repSlotStat.plugin_has_stats = true;
+		repSlotStat.sent_txns = stats->sentTxns;
+		repSlotStat.sent_bytes = stats->sentBytes;
+		repSlotStat.filtered_bytes = stats->filteredBytes;
+	}
+	else
+		repSlotStat.plugin_has_stats = false;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1988,6 +2002,12 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->streamBytes = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	if (stats)
+	{
+		stats->sentTxns = 0;
+		stats->sentBytes = 0;
+		stats->filteredBytes = 0;
+	}
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 25f890ddeed..788967e2ab1 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -89,6 +89,13 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/*
+	 * If output plugin has chosen to maintain its stats, update the amount of
+	 * data sent downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 4736f993c37..12579dff2c1 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -4436,7 +4435,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 80540c017bd..339babbeb56 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -450,6 +450,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 										 ALLOCSET_SMALL_SIZES);
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	/* This plugin uses binary protocol. */
 	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
@@ -591,6 +592,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	OutputPluginPrepareWrite(ctx, !send_replication_origin);
 	logicalrep_write_begin(ctx->out, txn);
 	txndata->sent_begin_txn = true;
+	ctx->stats->sentTxns++;
 
 	send_repl_origin(ctx, txn->origin_id, txn->origin_lsn,
 					 send_replication_origin);
@@ -1469,7 +1471,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TupleTableSlot *new_slot = NULL;
 
 	if (!is_publishable_relation(relation))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		return;
+	}
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1487,15 +1492,24 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1505,6 +1519,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
 			}
 			break;
@@ -1560,7 +1575,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		goto cleanup;
+	}
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1688,6 +1706,9 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
 	}
+	else
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
+
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 59822f22b8d..d9217ce49aa 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1573,6 +1573,13 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/*
+	 * If output plugin maintains statistics, update the amount of data sent
+	 * downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + 1; /* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index ccfb11c49bf..ed055324a99 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -96,6 +96,13 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_bytes);
 	REPLSLOT_ACC(total_txns);
 	REPLSLOT_ACC(total_bytes);
+	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
+	if (repSlotStat->plugin_has_stats)
+	{
+		REPLSLOT_ACC(sent_txns);
+		REPLSLOT_ACC(sent_bytes);
+		REPLSLOT_ACC(filtered_bytes);
+	}
 #undef REPLSLOT_ACC
 
 	pgstat_unlock_entry(entry_ref);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..15bafe63b24 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2100,7 +2100,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 10
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 13
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2125,11 +2125,17 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "stream_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_txns",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_wal_txns",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_bytes",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_wal_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "plugin_filtered_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "plugin_sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "plugin_sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2154,11 +2160,23 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[6] = Int64GetDatum(slotent->stream_bytes);
 	values[7] = Int64GetDatum(slotent->total_txns);
 	values[8] = Int64GetDatum(slotent->total_bytes);
+	if (slotent->plugin_has_stats)
+	{
+		values[9] = Int64GetDatum(slotent->filtered_bytes);
+		values[10] = Int64GetDatum(slotent->sent_txns);
+		values[11] = Int64GetDatum(slotent->sent_bytes);
+	}
+	else
+	{
+		nulls[9] = true;
+		nulls[10] = true;
+		nulls[11] = true;
+	}
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[9] = true;
+		nulls[12] = true;
 	else
-		values[9] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[12] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 01eba3b5a19..9e4f6620214 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5687,9 +5687,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_wal_txns,total_wal_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index f402b17295c..87afeaed8a5 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -395,6 +395,10 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_bytes;
 	PgStat_Counter total_txns;
 	PgStat_Counter total_bytes;
+	bool		plugin_has_stats;
+	PgStat_Counter sent_txns;
+	PgStat_Counter sent_bytes;
+	PgStat_Counter filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 2e562bee5a9..010c59f783d 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -52,6 +52,7 @@ typedef struct LogicalDecodingContext
 
 	OutputPluginCallbacks callbacks;
 	OutputPluginOptions options;
+	OutputPluginStats *stats;
 
 	/*
 	 * User specified options
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..02018f0593c 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -29,6 +29,19 @@ typedef struct OutputPluginOptions
 	bool		receive_rewrites;
 } OutputPluginOptions;
 
+/*
+ * Statistics about the transactions decoded and sent downstream by the output
+ * plugin.
+ */
+typedef struct OutputPluginStats
+{
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data from reoder buffer that was
+								 * filtered out by the output plugin */
+} OutputPluginStats;
+
 /*
  * Type of the shared library symbol _PG_output_plugin_init that is looked up
  * when loading an output plugin shared library.
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index fa0745552f8..3ea2d9885b6 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -715,6 +715,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index 2137c4e5e30..b04a0d9f8db 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -212,10 +212,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -233,10 +233,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..2a401552a7a 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2132,17 +2132,21 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
     s.stream_txns,
     s.stream_count,
     s.stream_bytes,
-    s.total_txns,
-    s.total_bytes,
+    s.total_wal_txns,
+    s.total_wal_bytes,
+    s.plugin_filtered_bytes,
+    s.plugin_sent_txns,
+    s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_wal_txns, total_wal_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 3c80d49b67e..b97915c1697 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1830,6 +1830,7 @@ OuterJoinClauseInfo
 OutputPluginCallbacks
 OutputPluginOptions
 OutputPluginOutputType
+OutputPluginStats
 OverridingKind
 PACE_HEADER
 PACL

base-commit: 5334620eef8f7b429594e6cf9dc97331eda2a8bd
-- 
2.34.1

From 95ddb15af81bca46e9d0739b96351167cad06e6c Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Tue, 23 Sep 2025 16:43:33 +0530
Subject: [PATCH 2/2] Address second round of comments from Shveta Malik

Add a test for plugin_filtered_bytes in logical replication case. We can
not test exact number of bytes filtered because of the unavoidable
background transaction activity which will be counted in the filtered
bytes.
---
 doc/src/sgml/logicaldecoding.sgml             | 13 ++++++------
 src/backend/replication/logical/logical.c     | 10 +++++-----
 .../replication/logical/logicalfuncs.c        |  1 +
 src/backend/utils/activity/pgstat_replslot.c  | 10 +++++-----
 src/backend/utils/adt/pgstatfuncs.c           | 10 +++++-----
 src/include/pgstat.h                          | 10 +++++-----
 src/test/recovery/t/006_logical_decoding.pl   |  6 +++---
 .../t/035_standby_logical_decoding.pl         |  4 ++--
 src/test/subscription/t/001_rep_changes.pl    | 11 ++++++++++
 src/test/subscription/t/010_truncate.pl       | 20 +++++++++++++++++++
 src/test/subscription/t/028_row_filter.pl     | 11 ++++++++++
 11 files changed, 75 insertions(+), 31 deletions(-)

diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index 3952f68e806..c02d4a88d57 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -956,12 +956,13 @@ typedef struct OutputPluginStats
 } OutputPluginStats;
 </programlisting>
       <literal>sentTxns</literal> is the number of transactions sent downstream
-      by the output plugin. <literal>sentBytes</literal> is the amount of data, in bytes,
-      sent downstream by the output plugin.
-      <function>OutputPluginWrite</function> will update this counter
-      if <literal>ctx-&gt;stats</literal> is initialized by the output plugin.
-      <literal>filteredBytes</literal> is the size of changes, in bytes, that are
-      filtered out by the output plugin. Function
+      by the output plugin. <literal>sentBytes</literal> is the amount of data,
+      in bytes, sent downstream by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that
+      are filtered out by the output plugin.
+      <function>OutputPluginWrite</function> will update
+      <literal>sentBytes</literal> if <literal>ctx-&gt;stats</literal> is
+      initialized by the output plugin. Function
       <literal>ReorderBufferChangeSize</literal> may be used to find the size of
       filtered <literal>ReorderBufferChange</literal>.
      </para>
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index b26ac29e32f..1435873101f 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1980,14 +1980,14 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_txns = rb->streamTxns;
 	repSlotStat.stream_count = rb->streamCount;
 	repSlotStat.stream_bytes = rb->streamBytes;
-	repSlotStat.total_txns = rb->totalTxns;
-	repSlotStat.total_bytes = rb->totalBytes;
+	repSlotStat.total_wal_txns = rb->totalTxns;
+	repSlotStat.total_wal_bytes = rb->totalBytes;
 	if (stats)
 	{
 		repSlotStat.plugin_has_stats = true;
-		repSlotStat.sent_txns = stats->sentTxns;
-		repSlotStat.sent_bytes = stats->sentBytes;
-		repSlotStat.filtered_bytes = stats->filteredBytes;
+		repSlotStat.plugin_sent_txns = stats->sentTxns;
+		repSlotStat.plugin_sent_bytes = stats->sentBytes;
+		repSlotStat.plugin_filtered_bytes = stats->filteredBytes;
 	}
 	else
 		repSlotStat.plugin_has_stats = false;
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 788967e2ab1..d2ab41de438 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -96,6 +96,7 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	 */
 	if (ctx->stats)
 		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
+
 	p->returned_rows++;
 }
 
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index ed055324a99..895940f4eb9 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -94,14 +94,14 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_txns);
 	REPLSLOT_ACC(stream_count);
 	REPLSLOT_ACC(stream_bytes);
-	REPLSLOT_ACC(total_txns);
-	REPLSLOT_ACC(total_bytes);
+	REPLSLOT_ACC(total_wal_txns);
+	REPLSLOT_ACC(total_wal_bytes);
 	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
 	if (repSlotStat->plugin_has_stats)
 	{
-		REPLSLOT_ACC(sent_txns);
-		REPLSLOT_ACC(sent_bytes);
-		REPLSLOT_ACC(filtered_bytes);
+		REPLSLOT_ACC(plugin_sent_txns);
+		REPLSLOT_ACC(plugin_sent_bytes);
+		REPLSLOT_ACC(plugin_filtered_bytes);
 	}
 #undef REPLSLOT_ACC
 
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 15bafe63b24..588b49059b2 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2158,13 +2158,13 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[4] = Int64GetDatum(slotent->stream_txns);
 	values[5] = Int64GetDatum(slotent->stream_count);
 	values[6] = Int64GetDatum(slotent->stream_bytes);
-	values[7] = Int64GetDatum(slotent->total_txns);
-	values[8] = Int64GetDatum(slotent->total_bytes);
+	values[7] = Int64GetDatum(slotent->total_wal_txns);
+	values[8] = Int64GetDatum(slotent->total_wal_bytes);
 	if (slotent->plugin_has_stats)
 	{
-		values[9] = Int64GetDatum(slotent->filtered_bytes);
-		values[10] = Int64GetDatum(slotent->sent_txns);
-		values[11] = Int64GetDatum(slotent->sent_bytes);
+		values[9] = Int64GetDatum(slotent->plugin_filtered_bytes);
+		values[10] = Int64GetDatum(slotent->plugin_sent_txns);
+		values[11] = Int64GetDatum(slotent->plugin_sent_bytes);
 	}
 	else
 	{
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 87afeaed8a5..33a031c79b4 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -393,12 +393,12 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_txns;
 	PgStat_Counter stream_count;
 	PgStat_Counter stream_bytes;
-	PgStat_Counter total_txns;
-	PgStat_Counter total_bytes;
+	PgStat_Counter total_wal_txns;
+	PgStat_Counter total_wal_bytes;
 	bool		plugin_has_stats;
-	PgStat_Counter sent_txns;
-	PgStat_Counter sent_bytes;
-	PgStat_Counter filtered_bytes;
+	PgStat_Counter plugin_sent_txns;
+	PgStat_Counter plugin_sent_bytes;
+	PgStat_Counter plugin_filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index b04a0d9f8db..92e42bec6a9 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -212,7 +212,7 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_wal_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
 	qq(t|t|t),
 	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
@@ -233,10 +233,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_wal_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
 	qq(t|t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_wal_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index c9c182892cf..c8577794eec 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -575,7 +575,7 @@ $node_primary->safe_psql('testdb',
 	qq[INSERT INTO decoding_test(x,y) SELECT 100,'100';]);
 
 $node_standby->poll_query_until('testdb',
-	qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+	qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 ) or die "replication slot stats of vacuum_full_activeslot not updated";
 
 # This should trigger the conflict
@@ -603,7 +603,7 @@ ok( $stderr =~
 # Ensure that replication slot stats are not removed after invalidation.
 is( $node_standby->safe_psql(
 		'testdb',
-		qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+		qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 	),
 	't',
 	'replication slot stats not removed after invalidation');
diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index ca55d8df50d..a7bee7fe5e4 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -124,6 +124,9 @@ $result =
   $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM tab_ins");
 is($result, qq(1002), 'check initial data was copied to subscriber');
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_ins SELECT generate_series(1,50)");
 $node_publisher->safe_psql('postgres', "DELETE FROM tab_ins WHERE a > 20");
@@ -157,6 +160,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup('tap_sub');
 
+# Verify that plugin_filtered_bytes increases due to filtered update and delete
+# operations on tab_ins.  We cannot test the exact value since it may include
+# changes from other concurrent transactions.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after DML filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab_ins");
 is($result, qq(1052|1|1002), 'check replicated inserts on subscriber');
diff --git a/src/test/subscription/t/010_truncate.pl b/src/test/subscription/t/010_truncate.pl
index 3d16c2a800d..c41ad317221 100644
--- a/src/test/subscription/t/010_truncate.pl
+++ b/src/test/subscription/t/010_truncate.pl
@@ -69,6 +69,9 @@ $node_subscriber->safe_psql('postgres',
 # Wait for initial sync of all subscriptions
 $node_subscriber->wait_for_subscription_sync;
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+
 # insert data to truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -98,6 +101,16 @@ $node_publisher->wait_for_catchup('sub1');
 $result = $node_subscriber->safe_psql('postgres', "SELECT nextval('seq1')");
 is($result, qq(101), 'truncate restarted identities');
 
+# All the DMLs above happen on tables that are subscribed to by sub1 and not
+# sub2. plugin_filtered_bytes should get incremented for replication slot
+# corresponding to the subscription sub2. We can not test the exact value of
+# plugin_filtered_bytes because the counter is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after publication level filtering');
+$initial_filtered_bytes = $final_filtered_bytes;
+
 # test publication that does not replicate truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -107,6 +120,13 @@ $node_publisher->safe_psql('postgres', "TRUNCATE tab2");
 
 $node_publisher->wait_for_catchup('sub2');
 
+# Truncate changes are filtered out at publication level itself. Make sure that
+# the plugin_filtered_bytes is incremented.
+$final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after truncate filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab2");
 is($result, qq(3|1|3), 'truncate not replicated');
diff --git a/src/test/subscription/t/028_row_filter.pl b/src/test/subscription/t/028_row_filter.pl
index e2c83670053..039bf5ff5a0 100644
--- a/src/test/subscription/t/028_row_filter.pl
+++ b/src/test/subscription/t/028_row_filter.pl
@@ -579,6 +579,9 @@ is($result, qq(3|6),
 # commands are for testing normal logical replication behavior.
 #
 # test row filter (INSERT, UPDATE, DELETE)
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_rowfilter_1 (a, b) VALUES (800, 'test 800')");
 $node_publisher->safe_psql('postgres',
@@ -612,6 +615,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup($appname);
 
+# The changes which do not pass the row filter will be filtered. Make sure that
+# the plugin_filtered_bytes reflects that. We can not test the exact value of
+# plugin_filtered_bytes since it is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after row filtering');
+
 # Check expected replicated rows for tab_rowfilter_2
 # tap_pub_1 filter is: (c % 2 = 0)
 # tap_pub_2 filter is: (c % 3 = 0)
-- 
2.34.1

diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index 895940f4eb9..e4dbbf4f405 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -80,12 +80,17 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	PgStat_EntryRef *entry_ref;
 	PgStatShared_ReplSlot *shstatent;
 	PgStat_StatReplSlotEntry *statent;
+	bool previous_had_stats;
+	bool current_has_stats;
 
 	entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_REPLSLOT, InvalidOid,
 											ReplicationSlotIndex(slot), false);
 	shstatent = (PgStatShared_ReplSlot *) entry_ref->shared_stats;
 	statent = &shstatent->stats;
 
+	previous_had_stats = statent->plugin_has_stats;
+	current_has_stats = repSlotStat->plugin_has_stats;
+
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
 	REPLSLOT_ACC(spill_txns);
@@ -97,7 +102,15 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(total_wal_txns);
 	REPLSLOT_ACC(total_wal_bytes);
 	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
-	if (repSlotStat->plugin_has_stats)
+
+	/* Plugin no longer supports stats, reset counters */
+	if (previous_had_stats && !current_has_stats) {
+		statent->plugin_sent_txns = 0;
+		statent->plugin_sent_bytes = 0;
+		statent->plugin_filtered_bytes = 0;
+	}
+
+	if (current_has_stats)
 	{
 		REPLSLOT_ACC(plugin_sent_txns);
 		REPLSLOT_ACC(plugin_sent_bytes);

From da8c610c0d2977f513fef25adb487ffd0199518d Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH 1/2] Report output plugin statistics in
 pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output plugin statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- plugin_filtered_bytes is the amount of changes filtered out by the
  output plugin
- plugin_sent_txns is the amount of transactions sent downstream by the
  output plugin
- plugin_sent_bytes is the amount of data sent downstream by the output
  plugin.

The prefix "plugin_" indicates that these counters are related to and
maintained by the output plugin. An output plugin may choose not to
initialize LogicalDecodingContext::stats, which holds these counters, in
which case the above columns will be reported as NULL.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Additionally report name of the output plugin in the view for an easy
reference.

total_bytes and total_txns are the only fields remaining unqualified -
they do not convey what those bytes and txns are. Hence rename them
total_wal_bytes and total_wal_txns respectively to indicate that those
counts come from WAL stream.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Shveta Malik <shveta.malik@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++++---------
 contrib/test_decoding/sql/stats.sql           | 16 ++--
 contrib/test_decoding/t/001_repl_stats.pl     | 22 ++++--
 contrib/test_decoding/test_decoding.c         |  2 +
 doc/src/sgml/logicaldecoding.sgml             | 28 +++++++
 doc/src/sgml/monitoring.sgml                  | 70 +++++++++++++++--
 src/backend/catalog/system_views.sql          |  8 +-
 src/backend/replication/logical/logical.c     | 28 ++++++-
 .../replication/logical/logicalfuncs.c        |  8 ++
 .../replication/logical/reorderbuffer.c       |  3 +-
 src/backend/replication/pgoutput/pgoutput.c   | 21 +++++
 src/backend/replication/walsender.c           |  7 ++
 src/backend/utils/activity/pgstat_replslot.c  | 11 ++-
 src/backend/utils/adt/pgstatfuncs.c           | 34 ++++++--
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  8 +-
 src/include/replication/logical.h             |  1 +
 src/include/replication/output_plugin.h       | 13 ++++
 src/include/replication/reorderbuffer.h       |  1 +
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 .../t/035_standby_logical_decoding.pl         |  4 +-
 src/test/regress/expected/rules.out           | 10 ++-
 src/test/subscription/t/001_rep_changes.pl    | 11 +++
 src/test/subscription/t/010_truncate.pl       | 20 +++++
 src/test/subscription/t/028_row_filter.pl     | 11 +++
 src/tools/pgindent/typedefs.list              |  1 +
 26 files changed, 344 insertions(+), 89 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index de6dc416130..4834b3460a6 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | t          | t
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |            | 
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | f          | f
- regression_slot_stats3 | t          | t           | f          | f
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+-------------------+-----------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats2 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats3 | t          | t           | f              | f               |                  |                   |                      
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index a022fe1bf07..99f513902d3 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,22 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +52,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..756fc691ed6 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, plugin_filtered_bytes may be greater than 0. But it's not
+	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
-		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+		SELECT slot_name, total_wal_txns > 0 AS total_txn,
+			   total_wal_bytes > 0 AS total_bytes,
+			   plugin_sent_txns > 0 AS sent_txn,
+			   plugin_sent_bytes > 0 AS sent_bytes,
+			   plugin_filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -65,7 +71,7 @@ $node->poll_query_until(
 	'postgres', qq[
 	SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
 	WHERE slot_name ~ 'regression_slot'
-	AND total_txns > 0 AND total_bytes > 0;
+	AND total_wal_txns > 0 AND total_wal_bytes > 0;
 ]) or die "Timed out while waiting for statistics to be updated";
 
 # Test to drop one of the replication slot and verify replication statistics data is
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index 36e77c69e1c..d06f6c3f92b 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -173,6 +173,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	data->only_local = false;
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
 	opt->receive_rewrites = false;
@@ -310,6 +311,7 @@ static void
 pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
 {
 	OutputPluginPrepareWrite(ctx, last_write);
+	ctx->stats->sentTxns++;
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
 	else
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index b803a819cf1..c02d4a88d57 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -938,6 +938,34 @@ typedef struct OutputPluginOptions
       needs to have a state, it can
       use <literal>ctx-&gt;output_plugin_private</literal> to store it.
      </para>
+
+     <para>
+      The startup callback may initialize <literal>ctx-&gt;stats</literal>,
+      typically as follows, if it chooses to maintain and report statistics
+      about its activity in <structname>pg_stat_replication_slots</structname>.
+<programlisting>
+ctx->stats = palloc0(sizeof(OutputPluginStats));
+</programlisting>
+      where <literal>OutputPluginStats</literal> is defined as follows:
+<programlisting>
+typedef struct OutputPluginStats
+{
+      int64   sentTxns;
+      int64   sentBytes;
+      int64   filteredBytes;
+} OutputPluginStats;
+</programlisting>
+      <literal>sentTxns</literal> is the number of transactions sent downstream
+      by the output plugin. <literal>sentBytes</literal> is the amount of data,
+      in bytes, sent downstream by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that
+      are filtered out by the output plugin.
+      <function>OutputPluginWrite</function> will update
+      <literal>sentBytes</literal> if <literal>ctx-&gt;stats</literal> is
+      initialized by the output plugin. Function
+      <literal>ReorderBufferChangeSize</literal> may be used to find the size of
+      filtered <literal>ReorderBufferChange</literal>.
+     </para>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..fbe03ffd670 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1545,6 +1545,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1622,19 +1633,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_txns</structfield> <type>bigint</type>
+        <structfield>total_wal_txns</structfield> <type>bigint</type>
        </para>
        <para>
-        Number of decoded transactions sent to the decoding output plugin for
-        this slot. This counts top-level transactions only, and is not incremented
-        for subtransactions. Note that this includes the transactions that are
-        streamed and/or spilled.
+        Number of decoded transactions from WAL sent to the decoding output
+        plugin for this slot. This counts top-level transactions only, and is
+        not incremented for subtransactions. Note that this includes the
+        transactions that are streamed and/or spilled.
        </para></entry>
      </row>
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_bytes</structfield><type>bigint</type>
+        <structfield>total_wal_bytes</structfield><type>bigint</type>
        </para>
        <para>
         Amount of transaction data decoded for sending transactions to the
@@ -1644,6 +1655,53 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is sent to
+        the output plugin, e.g. the changes filtered by origin. The count is
+        maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>. It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transctions sent to
+        the decoding plugin. Hence this count is expected to be lesser than or
+        equal to <structfield>total_wal_txns</structfield>.  The count is maintained
+        by the output plugin mentioned in <structfield>plugin</structfield>.  It
+        is NULL when statistics is not initialized or immediately after a reset or
+        when not maintained by the output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes sent downstream for this slot by the
+        output plugin after applying filtering and converting into its output
+        format. The count is maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>.  It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index c77fa0234bb..9e8e32b5849 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1053,14 +1053,18 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
             s.stream_txns,
             s.stream_count,
             s.stream_bytes,
-            s.total_txns,
-            s.total_bytes,
+            s.total_wal_txns,
+            s.total_wal_bytes,
+            s.plugin_filtered_bytes,
+            s.plugin_sent_txns,
+            s.plugin_sent_bytes,
             s.stats_reset
     FROM pg_replication_slots as r,
         LATERAL pg_stat_get_replication_slot(slot_name) as s
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index c68c0481f42..1435873101f 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1952,13 +1952,14 @@ void
 UpdateDecodingStats(LogicalDecodingContext *ctx)
 {
 	ReorderBuffer *rb = ctx->reorder;
+	OutputPluginStats *stats = ctx->stats;
 	PgStat_StatReplSlotEntry repSlotStat;
 
 	/* Nothing to do if we don't have any replication stats to be sent. */
 	if (rb->spillBytes <= 0 && rb->streamBytes <= 0 && rb->totalBytes <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " (%s) %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1967,7 +1968,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamCount,
 		 rb->streamBytes,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 stats ? "plugin has stats" : "plugin has no stats",
+		 stats ? stats->sentTxns : 0,
+		 stats ? stats->sentBytes : 0,
+		 stats ? stats->filteredBytes : 0);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1975,8 +1980,17 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_txns = rb->streamTxns;
 	repSlotStat.stream_count = rb->streamCount;
 	repSlotStat.stream_bytes = rb->streamBytes;
-	repSlotStat.total_txns = rb->totalTxns;
-	repSlotStat.total_bytes = rb->totalBytes;
+	repSlotStat.total_wal_txns = rb->totalTxns;
+	repSlotStat.total_wal_bytes = rb->totalBytes;
+	if (stats)
+	{
+		repSlotStat.plugin_has_stats = true;
+		repSlotStat.plugin_sent_txns = stats->sentTxns;
+		repSlotStat.plugin_sent_bytes = stats->sentBytes;
+		repSlotStat.plugin_filtered_bytes = stats->filteredBytes;
+	}
+	else
+		repSlotStat.plugin_has_stats = false;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1988,6 +2002,12 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->streamBytes = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	if (stats)
+	{
+		stats->sentTxns = 0;
+		stats->sentBytes = 0;
+		stats->filteredBytes = 0;
+	}
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 25f890ddeed..d2ab41de438 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -89,6 +89,14 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/*
+	 * If output plugin has chosen to maintain its stats, update the amount of
+	 * data sent downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
+
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index a5e165fb123..840deb5a3b7 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -4436,7 +4435,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 92eb17049c3..f87ab5e1d4b 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -450,6 +450,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 										 ALLOCSET_SMALL_SIZES);
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	/* This plugin uses binary protocol. */
 	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
@@ -591,6 +592,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	OutputPluginPrepareWrite(ctx, !send_replication_origin);
 	logicalrep_write_begin(ctx->out, txn);
 	txndata->sent_begin_txn = true;
+	ctx->stats->sentTxns++;
 
 	send_repl_origin(ctx, txn->origin_id, txn->origin_lsn,
 					 send_replication_origin);
@@ -1469,7 +1471,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TupleTableSlot *new_slot = NULL;
 
 	if (!is_publishable_relation(relation))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		return;
+	}
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1487,15 +1492,24 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1505,6 +1519,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
 			}
 			break;
@@ -1560,7 +1575,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		goto cleanup;
+	}
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1688,6 +1706,9 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
 	}
+	else
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
+
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 59822f22b8d..d9217ce49aa 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1573,6 +1573,13 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/*
+	 * If output plugin maintains statistics, update the amount of data sent
+	 * downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + 1; /* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index ccfb11c49bf..895940f4eb9 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -94,8 +94,15 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_txns);
 	REPLSLOT_ACC(stream_count);
 	REPLSLOT_ACC(stream_bytes);
-	REPLSLOT_ACC(total_txns);
-	REPLSLOT_ACC(total_bytes);
+	REPLSLOT_ACC(total_wal_txns);
+	REPLSLOT_ACC(total_wal_bytes);
+	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
+	if (repSlotStat->plugin_has_stats)
+	{
+		REPLSLOT_ACC(plugin_sent_txns);
+		REPLSLOT_ACC(plugin_sent_bytes);
+		REPLSLOT_ACC(plugin_filtered_bytes);
+	}
 #undef REPLSLOT_ACC
 
 	pgstat_unlock_entry(entry_ref);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..588b49059b2 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2100,7 +2100,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 10
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 13
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2125,11 +2125,17 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "stream_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_txns",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_wal_txns",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_bytes",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_wal_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "plugin_filtered_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "plugin_sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "plugin_sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2152,13 +2158,25 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[4] = Int64GetDatum(slotent->stream_txns);
 	values[5] = Int64GetDatum(slotent->stream_count);
 	values[6] = Int64GetDatum(slotent->stream_bytes);
-	values[7] = Int64GetDatum(slotent->total_txns);
-	values[8] = Int64GetDatum(slotent->total_bytes);
+	values[7] = Int64GetDatum(slotent->total_wal_txns);
+	values[8] = Int64GetDatum(slotent->total_wal_bytes);
+	if (slotent->plugin_has_stats)
+	{
+		values[9] = Int64GetDatum(slotent->plugin_filtered_bytes);
+		values[10] = Int64GetDatum(slotent->plugin_sent_txns);
+		values[11] = Int64GetDatum(slotent->plugin_sent_bytes);
+	}
+	else
+	{
+		nulls[9] = true;
+		nulls[10] = true;
+		nulls[11] = true;
+	}
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[9] = true;
+		nulls[12] = true;
 	else
-		values[9] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[12] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 01eba3b5a19..9e4f6620214 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5687,9 +5687,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_wal_txns,total_wal_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index e4a59a30b8c..7c680c21f55 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -394,8 +394,12 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_txns;
 	PgStat_Counter stream_count;
 	PgStat_Counter stream_bytes;
-	PgStat_Counter total_txns;
-	PgStat_Counter total_bytes;
+	PgStat_Counter total_wal_txns;
+	PgStat_Counter total_wal_bytes;
+	bool		plugin_has_stats;
+	PgStat_Counter plugin_sent_txns;
+	PgStat_Counter plugin_sent_bytes;
+	PgStat_Counter plugin_filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 2e562bee5a9..010c59f783d 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -52,6 +52,7 @@ typedef struct LogicalDecodingContext
 
 	OutputPluginCallbacks callbacks;
 	OutputPluginOptions options;
+	OutputPluginStats *stats;
 
 	/*
 	 * User specified options
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..02018f0593c 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -29,6 +29,19 @@ typedef struct OutputPluginOptions
 	bool		receive_rewrites;
 } OutputPluginOptions;
 
+/*
+ * Statistics about the transactions decoded and sent downstream by the output
+ * plugin.
+ */
+typedef struct OutputPluginStats
+{
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data from reoder buffer that was
+								 * filtered out by the output plugin */
+} OutputPluginStats;
+
 /*
  * Type of the shared library symbol _PG_output_plugin_init that is looked up
  * when loading an output plugin shared library.
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 91dc7e5e448..f5a4c35995c 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -715,6 +715,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index 2137c4e5e30..92e42bec6a9 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -212,10 +212,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_wal_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -233,10 +233,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_wal_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_wal_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index c9c182892cf..c8577794eec 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -575,7 +575,7 @@ $node_primary->safe_psql('testdb',
 	qq[INSERT INTO decoding_test(x,y) SELECT 100,'100';]);
 
 $node_standby->poll_query_until('testdb',
-	qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+	qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 ) or die "replication slot stats of vacuum_full_activeslot not updated";
 
 # This should trigger the conflict
@@ -603,7 +603,7 @@ ok( $stderr =~
 # Ensure that replication slot stats are not removed after invalidation.
 is( $node_standby->safe_psql(
 		'testdb',
-		qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+		qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 	),
 	't',
 	'replication slot stats not removed after invalidation');
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..2a401552a7a 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2132,17 +2132,21 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
     s.stream_txns,
     s.stream_count,
     s.stream_bytes,
-    s.total_txns,
-    s.total_bytes,
+    s.total_wal_txns,
+    s.total_wal_bytes,
+    s.plugin_filtered_bytes,
+    s.plugin_sent_txns,
+    s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_wal_txns, total_wal_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index ca55d8df50d..a7bee7fe5e4 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -124,6 +124,9 @@ $result =
   $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM tab_ins");
 is($result, qq(1002), 'check initial data was copied to subscriber');
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_ins SELECT generate_series(1,50)");
 $node_publisher->safe_psql('postgres', "DELETE FROM tab_ins WHERE a > 20");
@@ -157,6 +160,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup('tap_sub');
 
+# Verify that plugin_filtered_bytes increases due to filtered update and delete
+# operations on tab_ins.  We cannot test the exact value since it may include
+# changes from other concurrent transactions.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after DML filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab_ins");
 is($result, qq(1052|1|1002), 'check replicated inserts on subscriber');
diff --git a/src/test/subscription/t/010_truncate.pl b/src/test/subscription/t/010_truncate.pl
index 3d16c2a800d..c41ad317221 100644
--- a/src/test/subscription/t/010_truncate.pl
+++ b/src/test/subscription/t/010_truncate.pl
@@ -69,6 +69,9 @@ $node_subscriber->safe_psql('postgres',
 # Wait for initial sync of all subscriptions
 $node_subscriber->wait_for_subscription_sync;
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+
 # insert data to truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -98,6 +101,16 @@ $node_publisher->wait_for_catchup('sub1');
 $result = $node_subscriber->safe_psql('postgres', "SELECT nextval('seq1')");
 is($result, qq(101), 'truncate restarted identities');
 
+# All the DMLs above happen on tables that are subscribed to by sub1 and not
+# sub2. plugin_filtered_bytes should get incremented for replication slot
+# corresponding to the subscription sub2. We can not test the exact value of
+# plugin_filtered_bytes because the counter is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after publication level filtering');
+$initial_filtered_bytes = $final_filtered_bytes;
+
 # test publication that does not replicate truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -107,6 +120,13 @@ $node_publisher->safe_psql('postgres', "TRUNCATE tab2");
 
 $node_publisher->wait_for_catchup('sub2');
 
+# Truncate changes are filtered out at publication level itself. Make sure that
+# the plugin_filtered_bytes is incremented.
+$final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after truncate filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab2");
 is($result, qq(3|1|3), 'truncate not replicated');
diff --git a/src/test/subscription/t/028_row_filter.pl b/src/test/subscription/t/028_row_filter.pl
index e2c83670053..039bf5ff5a0 100644
--- a/src/test/subscription/t/028_row_filter.pl
+++ b/src/test/subscription/t/028_row_filter.pl
@@ -579,6 +579,9 @@ is($result, qq(3|6),
 # commands are for testing normal logical replication behavior.
 #
 # test row filter (INSERT, UPDATE, DELETE)
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_rowfilter_1 (a, b) VALUES (800, 'test 800')");
 $node_publisher->safe_psql('postgres',
@@ -612,6 +615,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup($appname);
 
+# The changes which do not pass the row filter will be filtered. Make sure that
+# the plugin_filtered_bytes reflects that. We can not test the exact value of
+# plugin_filtered_bytes since it is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after row filtering');
+
 # Check expected replicated rows for tab_rowfilter_2
 # tap_pub_1 filter is: (c % 2 = 0)
 # tap_pub_2 filter is: (c % 3 = 0)
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 37f26f6c6b7..02f984770f7 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1830,6 +1830,7 @@ OuterJoinClauseInfo
 OutputPluginCallbacks
 OutputPluginOptions
 OutputPluginOutputType
+OutputPluginStats
 OverridingKind
 PACE_HEADER
 PACL

base-commit: 902c08887aa183100b161ef48f1a2434af079213
-- 
2.34.1

From 4d3e61b362b794a99ca72cc8107d2ed72020fa04 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Thu, 25 Sep 2025 10:15:43 +0530
Subject: [PATCH 2/2] Address review comments from Bertrand

When the stats are not enabled, we should reset the plugin stats to 0, rather
than carrying over the stale stats from the time when the plugin was supporting
the stats. This does not matter if the plugin continues not to support
statistics forever. But in case it was supporting the stats once, discontinued
doing so at some point in time and then starts supporting the stats later,
accumulating the new stats based on the earlier accumulated stats could be
misleading.

Author: Ashutosh Bapat
---
 doc/src/sgml/monitoring.sgml                 | 10 +++++-----
 src/backend/utils/activity/pgstat_replslot.c |  7 +++++++
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fbe03ffd670..4d414d71742 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1663,7 +1663,7 @@ description | Waiting for a newly initialized WAL file to reach durable storage
         Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
         out by the output plugin and not sent downstream. Please note that it
         does not include the changes filtered before a change is sent to
-        the output plugin, e.g. the changes filtered by origin. The count is
+        the output plugin, e.g. the changes filtered by origin. The counter is
         maintained by the output plugin mentioned in
         <structfield>plugin</structfield>. It is NULL when statistics is not
         initialized or immediately after a reset or when not maintained by the
@@ -1678,9 +1678,9 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        <para>
         Number of decoded transactions sent downstream for this slot. This
         counts top-level transactions only, and is not incremented for
-        subtransactions. These transactions are subset of transctions sent to
-        the decoding plugin. Hence this count is expected to be lesser than or
-        equal to <structfield>total_wal_txns</structfield>.  The count is maintained
+        subtransactions. These transactions are subset of transactions sent to
+        the decoding plugin. Hence this count is expected to be less than or
+        equal to <structfield>total_wal_txns</structfield>.  The counter is maintained
         by the output plugin mentioned in <structfield>plugin</structfield>.  It
         is NULL when statistics is not initialized or immediately after a reset or
         when not maintained by the output plugin.
@@ -1694,7 +1694,7 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        <para>
         Amount of transaction changes sent downstream for this slot by the
         output plugin after applying filtering and converting into its output
-        format. The count is maintained by the output plugin mentioned in
+        format. The counter is maintained by the output plugin mentioned in
         <structfield>plugin</structfield>.  It is NULL when statistics is not
         initialized or immediately after a reset or when not maintained by the
         output plugin.
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index 895940f4eb9..3e486fd28e4 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -88,6 +88,7 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
+#define REPLSLOT_SET_TO_ZERO(fld) statent->fld = 0
 	REPLSLOT_ACC(spill_txns);
 	REPLSLOT_ACC(spill_count);
 	REPLSLOT_ACC(spill_bytes);
@@ -103,6 +104,12 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 		REPLSLOT_ACC(plugin_sent_bytes);
 		REPLSLOT_ACC(plugin_filtered_bytes);
 	}
+	else
+	{
+		REPLSLOT_SET_TO_ZERO(plugin_sent_txns);
+		REPLSLOT_SET_TO_ZERO(plugin_sent_bytes);
+		REPLSLOT_SET_TO_ZERO(plugin_filtered_bytes);
+	}
 #undef REPLSLOT_ACC
 
 	pgstat_unlock_entry(entry_ref);
-- 
2.34.1

From 8884d63f49b998e0b586a0e80f8e899811cd6d76 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH 1/2] Report output plugin statistics in
 pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output plugin statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- plugin_filtered_bytes is the amount of changes filtered out by the
  output plugin
- plugin_sent_txns is the amount of transactions sent downstream by the
  output plugin
- plugin_sent_bytes is the amount of data sent downstream by the output
  plugin.

The prefix "plugin_" indicates that these counters are related to and
maintained by the output plugin. An output plugin may choose not to
initialize LogicalDecodingContext::stats, which holds these counters, in
which case the above columns will be reported as NULL.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Additionally report name of the output plugin in the view for an easy
reference.

total_bytes and total_txns are the only fields remaining unqualified -
they do not convey what those bytes and txns are. Hence rename them
total_wal_bytes and total_wal_txns respectively to indicate that those
counts come from WAL stream.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Shveta Malik <shveta.malik@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++++---------
 contrib/test_decoding/sql/stats.sql           | 16 ++--
 contrib/test_decoding/t/001_repl_stats.pl     | 22 ++++--
 contrib/test_decoding/test_decoding.c         |  2 +
 doc/src/sgml/logicaldecoding.sgml             | 28 +++++++
 doc/src/sgml/monitoring.sgml                  | 70 +++++++++++++++--
 src/backend/catalog/system_views.sql          |  8 +-
 src/backend/replication/logical/logical.c     | 28 ++++++-
 .../replication/logical/logicalfuncs.c        |  8 ++
 .../replication/logical/reorderbuffer.c       |  3 +-
 src/backend/replication/pgoutput/pgoutput.c   | 21 +++++
 src/backend/replication/walsender.c           |  7 ++
 src/backend/utils/activity/pgstat_replslot.c  | 11 ++-
 src/backend/utils/adt/pgstatfuncs.c           | 34 ++++++--
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  8 +-
 src/include/replication/logical.h             |  1 +
 src/include/replication/output_plugin.h       | 13 ++++
 src/include/replication/reorderbuffer.h       |  1 +
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 .../t/035_standby_logical_decoding.pl         |  4 +-
 src/test/regress/expected/rules.out           | 10 ++-
 src/test/subscription/t/001_rep_changes.pl    | 11 +++
 src/test/subscription/t/010_truncate.pl       | 20 +++++
 src/test/subscription/t/028_row_filter.pl     | 11 +++
 src/tools/pgindent/typedefs.list              |  1 +
 26 files changed, 344 insertions(+), 89 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index de6dc416130..4834b3460a6 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | t          | t
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | t          | t
- regression_slot_stats3 | t          | t           | t          | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |            | 
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes 
-------------------------+------------+-------------+------------+-------------
- regression_slot_stats1 | t          | t           | f          | f
- regression_slot_stats2 | t          | t           | f          | f
- regression_slot_stats3 | t          | t           | f          | f
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes 
+------------------------+------------+-------------+----------------+-----------------+------------------+-------------------+-----------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats2 | t          | t           | f              | f               |                  |                   |                      
+ regression_slot_stats3 | t          | t           | f              | f               |                  |                   |                      
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index a022fe1bf07..99f513902d3 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,22 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +52,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count F
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..756fc691ed6 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, plugin_filtered_bytes may be greater than 0. But it's not
+	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
-		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+		SELECT slot_name, total_wal_txns > 0 AS total_txn,
+			   total_wal_bytes > 0 AS total_bytes,
+			   plugin_sent_txns > 0 AS sent_txn,
+			   plugin_sent_bytes > 0 AS sent_bytes,
+			   plugin_filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -65,7 +71,7 @@ $node->poll_query_until(
 	'postgres', qq[
 	SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
 	WHERE slot_name ~ 'regression_slot'
-	AND total_txns > 0 AND total_bytes > 0;
+	AND total_wal_txns > 0 AND total_wal_bytes > 0;
 ]) or die "Timed out while waiting for statistics to be updated";
 
 # Test to drop one of the replication slot and verify replication statistics data is
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index 36e77c69e1c..d06f6c3f92b 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -173,6 +173,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	data->only_local = false;
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
 	opt->receive_rewrites = false;
@@ -310,6 +311,7 @@ static void
 pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
 {
 	OutputPluginPrepareWrite(ctx, last_write);
+	ctx->stats->sentTxns++;
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
 	else
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index b803a819cf1..c02d4a88d57 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -938,6 +938,34 @@ typedef struct OutputPluginOptions
       needs to have a state, it can
       use <literal>ctx-&gt;output_plugin_private</literal> to store it.
      </para>
+
+     <para>
+      The startup callback may initialize <literal>ctx-&gt;stats</literal>,
+      typically as follows, if it chooses to maintain and report statistics
+      about its activity in <structname>pg_stat_replication_slots</structname>.
+<programlisting>
+ctx->stats = palloc0(sizeof(OutputPluginStats));
+</programlisting>
+      where <literal>OutputPluginStats</literal> is defined as follows:
+<programlisting>
+typedef struct OutputPluginStats
+{
+      int64   sentTxns;
+      int64   sentBytes;
+      int64   filteredBytes;
+} OutputPluginStats;
+</programlisting>
+      <literal>sentTxns</literal> is the number of transactions sent downstream
+      by the output plugin. <literal>sentBytes</literal> is the amount of data,
+      in bytes, sent downstream by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that
+      are filtered out by the output plugin.
+      <function>OutputPluginWrite</function> will update
+      <literal>sentBytes</literal> if <literal>ctx-&gt;stats</literal> is
+      initialized by the output plugin. Function
+      <literal>ReorderBufferChangeSize</literal> may be used to find the size of
+      filtered <literal>ReorderBufferChange</literal>.
+     </para>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 3f4a27a736e..fbe03ffd670 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1545,6 +1545,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1622,19 +1633,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_txns</structfield> <type>bigint</type>
+        <structfield>total_wal_txns</structfield> <type>bigint</type>
        </para>
        <para>
-        Number of decoded transactions sent to the decoding output plugin for
-        this slot. This counts top-level transactions only, and is not incremented
-        for subtransactions. Note that this includes the transactions that are
-        streamed and/or spilled.
+        Number of decoded transactions from WAL sent to the decoding output
+        plugin for this slot. This counts top-level transactions only, and is
+        not incremented for subtransactions. Note that this includes the
+        transactions that are streamed and/or spilled.
        </para></entry>
      </row>
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_bytes</structfield><type>bigint</type>
+        <structfield>total_wal_bytes</structfield><type>bigint</type>
        </para>
        <para>
         Amount of transaction data decoded for sending transactions to the
@@ -1644,6 +1655,53 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is sent to
+        the output plugin, e.g. the changes filtered by origin. The count is
+        maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>. It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transctions sent to
+        the decoding plugin. Hence this count is expected to be lesser than or
+        equal to <structfield>total_wal_txns</structfield>.  The count is maintained
+        by the output plugin mentioned in <structfield>plugin</structfield>.  It
+        is NULL when statistics is not initialized or immediately after a reset or
+        when not maintained by the output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes sent downstream for this slot by the
+        output plugin after applying filtering and converting into its output
+        format. The count is maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>.  It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index c77fa0234bb..9e8e32b5849 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1053,14 +1053,18 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
             s.stream_txns,
             s.stream_count,
             s.stream_bytes,
-            s.total_txns,
-            s.total_bytes,
+            s.total_wal_txns,
+            s.total_wal_bytes,
+            s.plugin_filtered_bytes,
+            s.plugin_sent_txns,
+            s.plugin_sent_bytes,
             s.stats_reset
     FROM pg_replication_slots as r,
         LATERAL pg_stat_get_replication_slot(slot_name) as s
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index c68c0481f42..1435873101f 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1952,13 +1952,14 @@ void
 UpdateDecodingStats(LogicalDecodingContext *ctx)
 {
 	ReorderBuffer *rb = ctx->reorder;
+	OutputPluginStats *stats = ctx->stats;
 	PgStat_StatReplSlotEntry repSlotStat;
 
 	/* Nothing to do if we don't have any replication stats to be sent. */
 	if (rb->spillBytes <= 0 && rb->streamBytes <= 0 && rb->totalBytes <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " (%s) %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1967,7 +1968,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamCount,
 		 rb->streamBytes,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 stats ? "plugin has stats" : "plugin has no stats",
+		 stats ? stats->sentTxns : 0,
+		 stats ? stats->sentBytes : 0,
+		 stats ? stats->filteredBytes : 0);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1975,8 +1980,17 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_txns = rb->streamTxns;
 	repSlotStat.stream_count = rb->streamCount;
 	repSlotStat.stream_bytes = rb->streamBytes;
-	repSlotStat.total_txns = rb->totalTxns;
-	repSlotStat.total_bytes = rb->totalBytes;
+	repSlotStat.total_wal_txns = rb->totalTxns;
+	repSlotStat.total_wal_bytes = rb->totalBytes;
+	if (stats)
+	{
+		repSlotStat.plugin_has_stats = true;
+		repSlotStat.plugin_sent_txns = stats->sentTxns;
+		repSlotStat.plugin_sent_bytes = stats->sentBytes;
+		repSlotStat.plugin_filtered_bytes = stats->filteredBytes;
+	}
+	else
+		repSlotStat.plugin_has_stats = false;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1988,6 +2002,12 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->streamBytes = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	if (stats)
+	{
+		stats->sentTxns = 0;
+		stats->sentBytes = 0;
+		stats->filteredBytes = 0;
+	}
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 25f890ddeed..d2ab41de438 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -89,6 +89,14 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/*
+	 * If output plugin has chosen to maintain its stats, update the amount of
+	 * data sent downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
+
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index a5e165fb123..840deb5a3b7 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -4436,7 +4435,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 92eb17049c3..f87ab5e1d4b 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -450,6 +450,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 										 ALLOCSET_SMALL_SIZES);
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	/* This plugin uses binary protocol. */
 	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
@@ -591,6 +592,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	OutputPluginPrepareWrite(ctx, !send_replication_origin);
 	logicalrep_write_begin(ctx->out, txn);
 	txndata->sent_begin_txn = true;
+	ctx->stats->sentTxns++;
 
 	send_repl_origin(ctx, txn->origin_id, txn->origin_lsn,
 					 send_replication_origin);
@@ -1469,7 +1471,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TupleTableSlot *new_slot = NULL;
 
 	if (!is_publishable_relation(relation))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		return;
+	}
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1487,15 +1492,24 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1505,6 +1519,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
 			}
 			break;
@@ -1560,7 +1575,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		goto cleanup;
+	}
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1688,6 +1706,9 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
 	}
+	else
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
+
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 59822f22b8d..d9217ce49aa 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1573,6 +1573,13 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/*
+	 * If output plugin maintains statistics, update the amount of data sent
+	 * downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + 1; /* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index ccfb11c49bf..895940f4eb9 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -94,8 +94,15 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_txns);
 	REPLSLOT_ACC(stream_count);
 	REPLSLOT_ACC(stream_bytes);
-	REPLSLOT_ACC(total_txns);
-	REPLSLOT_ACC(total_bytes);
+	REPLSLOT_ACC(total_wal_txns);
+	REPLSLOT_ACC(total_wal_bytes);
+	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
+	if (repSlotStat->plugin_has_stats)
+	{
+		REPLSLOT_ACC(plugin_sent_txns);
+		REPLSLOT_ACC(plugin_sent_bytes);
+		REPLSLOT_ACC(plugin_filtered_bytes);
+	}
 #undef REPLSLOT_ACC
 
 	pgstat_unlock_entry(entry_ref);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index c756c2bebaa..588b49059b2 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2100,7 +2100,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 10
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 13
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2125,11 +2125,17 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "stream_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_txns",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "total_wal_txns",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_bytes",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_wal_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "plugin_filtered_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "plugin_sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "plugin_sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2152,13 +2158,25 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[4] = Int64GetDatum(slotent->stream_txns);
 	values[5] = Int64GetDatum(slotent->stream_count);
 	values[6] = Int64GetDatum(slotent->stream_bytes);
-	values[7] = Int64GetDatum(slotent->total_txns);
-	values[8] = Int64GetDatum(slotent->total_bytes);
+	values[7] = Int64GetDatum(slotent->total_wal_txns);
+	values[8] = Int64GetDatum(slotent->total_wal_bytes);
+	if (slotent->plugin_has_stats)
+	{
+		values[9] = Int64GetDatum(slotent->plugin_filtered_bytes);
+		values[10] = Int64GetDatum(slotent->plugin_sent_txns);
+		values[11] = Int64GetDatum(slotent->plugin_sent_bytes);
+	}
+	else
+	{
+		nulls[9] = true;
+		nulls[10] = true;
+		nulls[11] = true;
+	}
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[9] = true;
+		nulls[12] = true;
 	else
-		values[9] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[12] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 01eba3b5a19..9e4f6620214 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5687,9 +5687,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_txns,total_bytes,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,total_wal_txns,total_wal_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index e4a59a30b8c..7c680c21f55 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -394,8 +394,12 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_txns;
 	PgStat_Counter stream_count;
 	PgStat_Counter stream_bytes;
-	PgStat_Counter total_txns;
-	PgStat_Counter total_bytes;
+	PgStat_Counter total_wal_txns;
+	PgStat_Counter total_wal_bytes;
+	bool		plugin_has_stats;
+	PgStat_Counter plugin_sent_txns;
+	PgStat_Counter plugin_sent_bytes;
+	PgStat_Counter plugin_filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 2e562bee5a9..010c59f783d 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -52,6 +52,7 @@ typedef struct LogicalDecodingContext
 
 	OutputPluginCallbacks callbacks;
 	OutputPluginOptions options;
+	OutputPluginStats *stats;
 
 	/*
 	 * User specified options
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..02018f0593c 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -29,6 +29,19 @@ typedef struct OutputPluginOptions
 	bool		receive_rewrites;
 } OutputPluginOptions;
 
+/*
+ * Statistics about the transactions decoded and sent downstream by the output
+ * plugin.
+ */
+typedef struct OutputPluginStats
+{
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data from reoder buffer that was
+								 * filtered out by the output plugin */
+} OutputPluginStats;
+
 /*
  * Type of the shared library symbol _PG_output_plugin_init that is looked up
  * when loading an output plugin shared library.
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 91dc7e5e448..f5a4c35995c 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -715,6 +715,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index 2137c4e5e30..92e42bec6a9 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -212,10 +212,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_wal_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -233,10 +233,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_wal_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_wal_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index c9c182892cf..c8577794eec 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -575,7 +575,7 @@ $node_primary->safe_psql('testdb',
 	qq[INSERT INTO decoding_test(x,y) SELECT 100,'100';]);
 
 $node_standby->poll_query_until('testdb',
-	qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+	qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 ) or die "replication slot stats of vacuum_full_activeslot not updated";
 
 # This should trigger the conflict
@@ -603,7 +603,7 @@ ok( $stderr =~
 # Ensure that replication slot stats are not removed after invalidation.
 is( $node_standby->safe_psql(
 		'testdb',
-		qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+		qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 	),
 	't',
 	'replication slot stats not removed after invalidation');
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 35e8aad7701..2a401552a7a 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2132,17 +2132,21 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
     s.stream_txns,
     s.stream_count,
     s.stream_bytes,
-    s.total_txns,
-    s.total_bytes,
+    s.total_wal_txns,
+    s.total_wal_bytes,
+    s.plugin_filtered_bytes,
+    s.plugin_sent_txns,
+    s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_txns, total_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, total_wal_txns, total_wal_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index ca55d8df50d..a7bee7fe5e4 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -124,6 +124,9 @@ $result =
   $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM tab_ins");
 is($result, qq(1002), 'check initial data was copied to subscriber');
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_ins SELECT generate_series(1,50)");
 $node_publisher->safe_psql('postgres', "DELETE FROM tab_ins WHERE a > 20");
@@ -157,6 +160,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup('tap_sub');
 
+# Verify that plugin_filtered_bytes increases due to filtered update and delete
+# operations on tab_ins.  We cannot test the exact value since it may include
+# changes from other concurrent transactions.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after DML filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab_ins");
 is($result, qq(1052|1|1002), 'check replicated inserts on subscriber');
diff --git a/src/test/subscription/t/010_truncate.pl b/src/test/subscription/t/010_truncate.pl
index 3d16c2a800d..c41ad317221 100644
--- a/src/test/subscription/t/010_truncate.pl
+++ b/src/test/subscription/t/010_truncate.pl
@@ -69,6 +69,9 @@ $node_subscriber->safe_psql('postgres',
 # Wait for initial sync of all subscriptions
 $node_subscriber->wait_for_subscription_sync;
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+
 # insert data to truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -98,6 +101,16 @@ $node_publisher->wait_for_catchup('sub1');
 $result = $node_subscriber->safe_psql('postgres', "SELECT nextval('seq1')");
 is($result, qq(101), 'truncate restarted identities');
 
+# All the DMLs above happen on tables that are subscribed to by sub1 and not
+# sub2. plugin_filtered_bytes should get incremented for replication slot
+# corresponding to the subscription sub2. We can not test the exact value of
+# plugin_filtered_bytes because the counter is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after publication level filtering');
+$initial_filtered_bytes = $final_filtered_bytes;
+
 # test publication that does not replicate truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -107,6 +120,13 @@ $node_publisher->safe_psql('postgres', "TRUNCATE tab2");
 
 $node_publisher->wait_for_catchup('sub2');
 
+# Truncate changes are filtered out at publication level itself. Make sure that
+# the plugin_filtered_bytes is incremented.
+$final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after truncate filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab2");
 is($result, qq(3|1|3), 'truncate not replicated');
diff --git a/src/test/subscription/t/028_row_filter.pl b/src/test/subscription/t/028_row_filter.pl
index e2c83670053..039bf5ff5a0 100644
--- a/src/test/subscription/t/028_row_filter.pl
+++ b/src/test/subscription/t/028_row_filter.pl
@@ -579,6 +579,9 @@ is($result, qq(3|6),
 # commands are for testing normal logical replication behavior.
 #
 # test row filter (INSERT, UPDATE, DELETE)
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_rowfilter_1 (a, b) VALUES (800, 'test 800')");
 $node_publisher->safe_psql('postgres',
@@ -612,6 +615,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup($appname);
 
+# The changes which do not pass the row filter will be filtered. Make sure that
+# the plugin_filtered_bytes reflects that. We can not test the exact value of
+# plugin_filtered_bytes since it is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after row filtering');
+
 # Check expected replicated rows for tab_rowfilter_2
 # tap_pub_1 filter is: (c % 2 = 0)
 # tap_pub_2 filter is: (c % 3 = 0)
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 37f26f6c6b7..02f984770f7 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1830,6 +1830,7 @@ OuterJoinClauseInfo
 OutputPluginCallbacks
 OutputPluginOptions
 OutputPluginOutputType
+OutputPluginStats
 OverridingKind
 PACE_HEADER
 PACL

base-commit: 0c7f103028202cec94e12cbe45cebdb5c8fbc392
-- 
2.34.1

From 72bb6a453e7e20239e0a900aeb555d9ab745d43e Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Thu, 25 Sep 2025 10:15:43 +0530
Subject: [PATCH 2/2] Address review comments from Bertrand

When the stats are not enabled, we should reset the plugin stats to 0, rather
than carrying over the stale stats from the time when the plugin was supporting
the stats. This does not matter if the plugin continues not to support
statistics forever. But in case it was supporting the stats once, discontinued
doing so at some point in time and then starts supporting the stats later,
accumulating the new stats based on the earlier accumulated stats could be
misleading.

Also add a note in the documentation mentioning that stats, once supported
should remain supported.

Author: Ashutosh Bapat
---
 doc/src/sgml/logicaldecoding.sgml            |  8 ++++++++
 doc/src/sgml/monitoring.sgml                 | 10 +++++-----
 src/backend/utils/activity/pgstat_replslot.c |  8 ++++++++
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index c02d4a88d57..0bf9ffbfd28 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -966,6 +966,14 @@ typedef struct OutputPluginStats
       <literal>ReorderBufferChangeSize</literal> may be used to find the size of
       filtered <literal>ReorderBufferChange</literal>.
      </para>
+
+     <note>
+      <para>
+       Once a plugin starts reporting and maintaining these statistics, it is
+       not expected that they will discontinue doing so. If they do, the result
+       may be misleading because of the cumulative nature of these statistics.
+      </para>
+     </note>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index fbe03ffd670..4d414d71742 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1663,7 +1663,7 @@ description | Waiting for a newly initialized WAL file to reach durable storage
         Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
         out by the output plugin and not sent downstream. Please note that it
         does not include the changes filtered before a change is sent to
-        the output plugin, e.g. the changes filtered by origin. The count is
+        the output plugin, e.g. the changes filtered by origin. The counter is
         maintained by the output plugin mentioned in
         <structfield>plugin</structfield>. It is NULL when statistics is not
         initialized or immediately after a reset or when not maintained by the
@@ -1678,9 +1678,9 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        <para>
         Number of decoded transactions sent downstream for this slot. This
         counts top-level transactions only, and is not incremented for
-        subtransactions. These transactions are subset of transctions sent to
-        the decoding plugin. Hence this count is expected to be lesser than or
-        equal to <structfield>total_wal_txns</structfield>.  The count is maintained
+        subtransactions. These transactions are subset of transactions sent to
+        the decoding plugin. Hence this count is expected to be less than or
+        equal to <structfield>total_wal_txns</structfield>.  The counter is maintained
         by the output plugin mentioned in <structfield>plugin</structfield>.  It
         is NULL when statistics is not initialized or immediately after a reset or
         when not maintained by the output plugin.
@@ -1694,7 +1694,7 @@ description | Waiting for a newly initialized WAL file to reach durable storage
        <para>
         Amount of transaction changes sent downstream for this slot by the
         output plugin after applying filtering and converting into its output
-        format. The count is maintained by the output plugin mentioned in
+        format. The counter is maintained by the output plugin mentioned in
         <structfield>plugin</structfield>.  It is NULL when statistics is not
         initialized or immediately after a reset or when not maintained by the
         output plugin.
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index 895940f4eb9..c3a2fe3d3f9 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -88,6 +88,7 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
+#define REPLSLOT_SET_TO_ZERO(fld) statent->fld = 0
 	REPLSLOT_ACC(spill_txns);
 	REPLSLOT_ACC(spill_count);
 	REPLSLOT_ACC(spill_bytes);
@@ -103,7 +104,14 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 		REPLSLOT_ACC(plugin_sent_bytes);
 		REPLSLOT_ACC(plugin_filtered_bytes);
 	}
+	else
+	{
+		REPLSLOT_SET_TO_ZERO(plugin_sent_txns);
+		REPLSLOT_SET_TO_ZERO(plugin_sent_bytes);
+		REPLSLOT_SET_TO_ZERO(plugin_filtered_bytes);
+	}
 #undef REPLSLOT_ACC
+#undef REPLSLOT_SET_TO_ZERO
 
 	pgstat_unlock_entry(entry_ref);
 }
-- 
2.34.1

From fdb428a07dce3de95103252f6334f2fee6650dcc Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH] Report output plugin statistics in pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output plugin statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- plugin_filtered_bytes is the amount of changes filtered out by the
  output plugin
- plugin_sent_txns is the amount of transactions sent downstream by the
  output plugin
- plugin_sent_bytes is the amount of data sent downstream by the output
  plugin.

The prefix "plugin_" indicates that these counters are related to and
maintained by the output plugin. An output plugin may choose not to
initialize LogicalDecodingContext::stats, which holds these counters, in
which case the above columns will be reported as NULL.

When the stats are disabled after being enabled for a while, the plugin
stats are reset to 0, rather than carrying over the stale stats from the
time when the plugin was supporting the stats. This does not matter if
the plugin continues not to support statistics forever. But in case it
was supporting the stats once, discontinued doing so at some point in
time and then starts supporting the stats later, accumulating the new
stats based on the earlier accumulated stats could be misleading.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Additionally report name of the output plugin in the view for an easy
reference.

total_bytes and total_txns are the only fields remaining unqualified -
they do not convey what those bytes and txns are. Hence rename them
total_wal_bytes and total_wal_txns respectively to indicate that those
counts come from WAL stream.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Shveta Malik <shveta.malik@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++++---------
 contrib/test_decoding/sql/stats.sql           | 16 ++--
 contrib/test_decoding/t/001_repl_stats.pl     | 22 ++++--
 contrib/test_decoding/test_decoding.c         |  2 +
 doc/src/sgml/logicaldecoding.sgml             | 36 +++++++++
 doc/src/sgml/monitoring.sgml                  | 70 +++++++++++++++--
 src/backend/catalog/system_views.sql          |  8 +-
 src/backend/replication/logical/logical.c     | 28 ++++++-
 .../replication/logical/logicalfuncs.c        |  8 ++
 .../replication/logical/reorderbuffer.c       |  3 +-
 src/backend/replication/pgoutput/pgoutput.c   | 21 +++++
 src/backend/replication/walsender.c           |  7 ++
 src/backend/utils/activity/pgstat_replslot.c  | 19 ++++-
 src/backend/utils/adt/pgstatfuncs.c           | 34 ++++++--
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  8 +-
 src/include/replication/logical.h             |  1 +
 src/include/replication/output_plugin.h       | 13 ++++
 src/include/replication/reorderbuffer.h       |  1 +
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 .../t/035_standby_logical_decoding.pl         |  4 +-
 src/test/regress/expected/rules.out           | 10 ++-
 src/test/subscription/t/001_rep_changes.pl    | 11 +++
 src/test/subscription/t/010_truncate.pl       | 20 +++++
 src/test/subscription/t/028_row_filter.pl     | 11 +++
 src/tools/pgindent/typedefs.list              |  1 +
 26 files changed, 360 insertions(+), 89 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index 28da9123cc8..0e5c5fa5b18 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | t          | t           | t
- regression_slot_stats2 | t          | t           | t          | t           | t
- regression_slot_stats3 | t          | t           | t          | t           | t
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------+--------------------
+ regression_slot_stats1 | t          | t           | t              | t               |                1 | t          | t              | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t              | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t              | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | f          | f           | t
- regression_slot_stats2 | t          | t           | t          | t           | t
- regression_slot_stats3 | t          | t           | t          | t           | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------+--------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |            |                | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t              | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t              | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | f          | f           | t
- regression_slot_stats2 | t          | t           | f          | f           | t
- regression_slot_stats3 | t          | t           | f          | f           | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+------------------+-------------------+-----------------------+--------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |                   |                       | t
+ regression_slot_stats2 | t          | t           | f              | f               |                  |                   |                       | t
+ regression_slot_stats3 | t          | t           | f              | f               |                  |                   |                       | t
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count,
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index 6661dbcb85c..d6bf3cde8b1 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,22 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +52,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count,
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..756fc691ed6 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, plugin_filtered_bytes may be greater than 0. But it's not
+	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
-		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+		SELECT slot_name, total_wal_txns > 0 AS total_txn,
+			   total_wal_bytes > 0 AS total_bytes,
+			   plugin_sent_txns > 0 AS sent_txn,
+			   plugin_sent_bytes > 0 AS sent_bytes,
+			   plugin_filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -65,7 +71,7 @@ $node->poll_query_until(
 	'postgres', qq[
 	SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
 	WHERE slot_name ~ 'regression_slot'
-	AND total_txns > 0 AND total_bytes > 0;
+	AND total_wal_txns > 0 AND total_wal_bytes > 0;
 ]) or die "Timed out while waiting for statistics to be updated";
 
 # Test to drop one of the replication slot and verify replication statistics data is
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index 36e77c69e1c..d06f6c3f92b 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -173,6 +173,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	data->only_local = false;
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
 	opt->receive_rewrites = false;
@@ -310,6 +311,7 @@ static void
 pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
 {
 	OutputPluginPrepareWrite(ctx, last_write);
+	ctx->stats->sentTxns++;
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
 	else
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index b803a819cf1..0bf9ffbfd28 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -938,6 +938,42 @@ typedef struct OutputPluginOptions
       needs to have a state, it can
       use <literal>ctx-&gt;output_plugin_private</literal> to store it.
      </para>
+
+     <para>
+      The startup callback may initialize <literal>ctx-&gt;stats</literal>,
+      typically as follows, if it chooses to maintain and report statistics
+      about its activity in <structname>pg_stat_replication_slots</structname>.
+<programlisting>
+ctx->stats = palloc0(sizeof(OutputPluginStats));
+</programlisting>
+      where <literal>OutputPluginStats</literal> is defined as follows:
+<programlisting>
+typedef struct OutputPluginStats
+{
+      int64   sentTxns;
+      int64   sentBytes;
+      int64   filteredBytes;
+} OutputPluginStats;
+</programlisting>
+      <literal>sentTxns</literal> is the number of transactions sent downstream
+      by the output plugin. <literal>sentBytes</literal> is the amount of data,
+      in bytes, sent downstream by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that
+      are filtered out by the output plugin.
+      <function>OutputPluginWrite</function> will update
+      <literal>sentBytes</literal> if <literal>ctx-&gt;stats</literal> is
+      initialized by the output plugin. Function
+      <literal>ReorderBufferChangeSize</literal> may be used to find the size of
+      filtered <literal>ReorderBufferChange</literal>.
+     </para>
+
+     <note>
+      <para>
+       Once a plugin starts reporting and maintaining these statistics, it is
+       not expected that they will discontinue doing so. If they do, the result
+       may be misleading because of the cumulative nature of these statistics.
+      </para>
+     </note>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index d5f0fb7ba7c..1ccf781f45e 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1549,6 +1549,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1637,19 +1648,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_txns</structfield> <type>bigint</type>
+        <structfield>total_wal_txns</structfield> <type>bigint</type>
        </para>
        <para>
-        Number of decoded transactions sent to the decoding output plugin for
-        this slot. This counts top-level transactions only, and is not incremented
-        for subtransactions. Note that this includes the transactions that are
-        streamed and/or spilled.
+        Number of decoded transactions from WAL sent to the decoding output
+        plugin for this slot. This counts top-level transactions only, and is
+        not incremented for subtransactions. Note that this includes the
+        transactions that are streamed and/or spilled.
        </para></entry>
      </row>
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_bytes</structfield><type>bigint</type>
+        <structfield>total_wal_bytes</structfield><type>bigint</type>
        </para>
        <para>
         Amount of transaction data decoded for sending transactions to the
@@ -1659,6 +1670,53 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is sent to
+        the output plugin, e.g. the changes filtered by origin. The counter is
+        maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>. It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transactions sent to
+        the decoding plugin. Hence this count is expected to be less than or
+        equal to <structfield>total_wal_txns</structfield>.  The counter is maintained
+        by the output plugin mentioned in <structfield>plugin</structfield>.  It
+        is NULL when statistics is not initialized or immediately after a reset or
+        when not maintained by the output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes sent downstream for this slot by the
+        output plugin after applying filtering and converting into its output
+        format. The counter is maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>.  It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 823776c1498..be91e9b01e4 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1067,6 +1067,7 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
@@ -1074,8 +1075,11 @@ CREATE VIEW pg_stat_replication_slots AS
             s.stream_count,
             s.stream_bytes,
             s.mem_exceeded_count,
-            s.total_txns,
-            s.total_bytes,
+            s.total_wal_txns,
+            s.total_wal_bytes,
+            s.plugin_filtered_bytes,
+            s.plugin_sent_txns,
+            s.plugin_sent_bytes,
             s.stats_reset
     FROM pg_replication_slots as r,
         LATERAL pg_stat_get_replication_slot(slot_name) as s
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 93ed2eb368e..f0810f05153 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1952,6 +1952,7 @@ void
 UpdateDecodingStats(LogicalDecodingContext *ctx)
 {
 	ReorderBuffer *rb = ctx->reorder;
+	OutputPluginStats *stats = ctx->stats;
 	PgStat_StatReplSlotEntry repSlotStat;
 
 	/* Nothing to do if we don't have any replication stats to be sent. */
@@ -1959,7 +1960,7 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		rb->memExceededCount <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " (%s) %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1969,7 +1970,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamBytes,
 		 rb->memExceededCount,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 stats ? "plugin has stats" : "plugin has no stats",
+		 stats ? stats->sentTxns : 0,
+		 stats ? stats->sentBytes : 0,
+		 stats ? stats->filteredBytes : 0);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1978,8 +1983,17 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_count = rb->streamCount;
 	repSlotStat.stream_bytes = rb->streamBytes;
 	repSlotStat.mem_exceeded_count = rb->memExceededCount;
-	repSlotStat.total_txns = rb->totalTxns;
-	repSlotStat.total_bytes = rb->totalBytes;
+	repSlotStat.total_wal_txns = rb->totalTxns;
+	repSlotStat.total_wal_bytes = rb->totalBytes;
+	if (stats)
+	{
+		repSlotStat.plugin_has_stats = true;
+		repSlotStat.plugin_sent_txns = stats->sentTxns;
+		repSlotStat.plugin_sent_bytes = stats->sentBytes;
+		repSlotStat.plugin_filtered_bytes = stats->filteredBytes;
+	}
+	else
+		repSlotStat.plugin_has_stats = false;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1992,6 +2006,12 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->memExceededCount = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	if (stats)
+	{
+		stats->sentTxns = 0;
+		stats->sentBytes = 0;
+		stats->filteredBytes = 0;
+	}
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 25f890ddeed..d2ab41de438 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -89,6 +89,14 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/*
+	 * If output plugin has chosen to maintain its stats, update the amount of
+	 * data sent downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
+
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index b57aef9916d..d336ef3a51f 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -4458,7 +4457,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 942e1abdb58..4b35f2de6aa 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -473,6 +473,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	MemoryContextRegisterResetCallback(ctx->context, mcallback);
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	/* This plugin uses binary protocol. */
 	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
@@ -614,6 +615,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	OutputPluginPrepareWrite(ctx, !send_replication_origin);
 	logicalrep_write_begin(ctx->out, txn);
 	txndata->sent_begin_txn = true;
+	ctx->stats->sentTxns++;
 
 	send_repl_origin(ctx, txn->origin_id, txn->origin_lsn,
 					 send_replication_origin);
@@ -1492,7 +1494,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TupleTableSlot *new_slot = NULL;
 
 	if (!is_publishable_relation(relation))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		return;
+	}
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1510,15 +1515,24 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1528,6 +1542,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
 			}
 			break;
@@ -1583,7 +1598,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		goto cleanup;
+	}
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1711,6 +1729,9 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
 	}
+	else
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
+
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 548eafa7a73..b0a5d4da7a7 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1587,6 +1587,13 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/*
+	 * If output plugin maintains statistics, update the amount of data sent
+	 * downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + 1; /* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index d210c261ac6..42ca13bd76a 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -88,6 +88,7 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
+#define REPLSLOT_SET_TO_ZERO(fld) statent->fld = 0
 	REPLSLOT_ACC(spill_txns);
 	REPLSLOT_ACC(spill_count);
 	REPLSLOT_ACC(spill_bytes);
@@ -95,9 +96,23 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_count);
 	REPLSLOT_ACC(stream_bytes);
 	REPLSLOT_ACC(mem_exceeded_count);
-	REPLSLOT_ACC(total_txns);
-	REPLSLOT_ACC(total_bytes);
+	REPLSLOT_ACC(total_wal_txns);
+	REPLSLOT_ACC(total_wal_bytes);
+	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
+	if (repSlotStat->plugin_has_stats)
+	{
+		REPLSLOT_ACC(plugin_sent_txns);
+		REPLSLOT_ACC(plugin_sent_bytes);
+		REPLSLOT_ACC(plugin_filtered_bytes);
+	}
+	else
+	{
+		REPLSLOT_SET_TO_ZERO(plugin_sent_txns);
+		REPLSLOT_SET_TO_ZERO(plugin_sent_bytes);
+		REPLSLOT_SET_TO_ZERO(plugin_filtered_bytes);
+	}
 #undef REPLSLOT_ACC
+#undef REPLSLOT_SET_TO_ZERO
 
 	pgstat_unlock_entry(entry_ref);
 }
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 1fe33df2756..be8d30ca9c6 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2121,7 +2121,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 11
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 14
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2148,11 +2148,17 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "mem_exceeded_count",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_txns",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_wal_txns",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "total_bytes",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "total_wal_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "plugin_filtered_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "plugin_sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "plugin_sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 14, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2176,13 +2182,25 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[5] = Int64GetDatum(slotent->stream_count);
 	values[6] = Int64GetDatum(slotent->stream_bytes);
 	values[7] = Int64GetDatum(slotent->mem_exceeded_count);
-	values[8] = Int64GetDatum(slotent->total_txns);
-	values[9] = Int64GetDatum(slotent->total_bytes);
+	values[8] = Int64GetDatum(slotent->total_wal_txns);
+	values[9] = Int64GetDatum(slotent->total_wal_bytes);
+	if (slotent->plugin_has_stats)
+	{
+		values[10] = Int64GetDatum(slotent->plugin_filtered_bytes);
+		values[11] = Int64GetDatum(slotent->plugin_sent_txns);
+		values[12] = Int64GetDatum(slotent->plugin_sent_bytes);
+	}
+	else
+	{
+		nulls[10] = true;
+		nulls[11] = true;
+		nulls[12] = true;
+	}
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[10] = true;
+		nulls[13] = true;
 	else
-		values[10] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[13] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index eecb43ec6f0..11404660a56 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5691,9 +5691,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,mem_exceeded_count,total_txns,total_bytes,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,mem_exceeded_count,total_wal_txns,total_wal_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index bc8077cbae6..ae11f39dd3b 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -396,8 +396,12 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_count;
 	PgStat_Counter stream_bytes;
 	PgStat_Counter mem_exceeded_count;
-	PgStat_Counter total_txns;
-	PgStat_Counter total_bytes;
+	PgStat_Counter total_wal_txns;
+	PgStat_Counter total_wal_bytes;
+	bool		plugin_has_stats;
+	PgStat_Counter plugin_sent_txns;
+	PgStat_Counter plugin_sent_bytes;
+	PgStat_Counter plugin_filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 2e562bee5a9..010c59f783d 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -52,6 +52,7 @@ typedef struct LogicalDecodingContext
 
 	OutputPluginCallbacks callbacks;
 	OutputPluginOptions options;
+	OutputPluginStats *stats;
 
 	/*
 	 * User specified options
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..02018f0593c 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -29,6 +29,19 @@ typedef struct OutputPluginOptions
 	bool		receive_rewrites;
 } OutputPluginOptions;
 
+/*
+ * Statistics about the transactions decoded and sent downstream by the output
+ * plugin.
+ */
+typedef struct OutputPluginStats
+{
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data from reoder buffer that was
+								 * filtered out by the output plugin */
+} OutputPluginStats;
+
 /*
  * Type of the shared library symbol _PG_output_plugin_init that is looked up
  * when loading an output plugin shared library.
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 3cbe106a3c7..382eba66a76 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -718,6 +718,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index f6c0a5bf649..be564b53bc6 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -215,10 +215,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_wal_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -236,10 +236,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_wal_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_wal_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index ebe2fae1789..5f4df30d65a 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -577,7 +577,7 @@ $node_primary->safe_psql('testdb',
 	qq[INSERT INTO decoding_test(x,y) SELECT 100,'100';]);
 
 $node_standby->poll_query_until('testdb',
-	qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+	qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 ) or die "replication slot stats of vacuum_full_activeslot not updated";
 
 # This should trigger the conflict
@@ -605,7 +605,7 @@ ok( $stderr =~
 # Ensure that replication slot stats are not removed after invalidation.
 is( $node_standby->safe_psql(
 		'testdb',
-		qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+		qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 	),
 	't',
 	'replication slot stats not removed after invalidation');
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 16753b2e4c0..d77059ae186 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2142,6 +2142,7 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
@@ -2149,11 +2150,14 @@ pg_stat_replication_slots| SELECT s.slot_name,
     s.stream_count,
     s.stream_bytes,
     s.mem_exceeded_count,
-    s.total_txns,
-    s.total_bytes,
+    s.total_wal_txns,
+    s.total_wal_bytes,
+    s.plugin_filtered_bytes,
+    s.plugin_sent_txns,
+    s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, mem_exceeded_count, total_txns, total_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, mem_exceeded_count, total_wal_txns, total_wal_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index 430c1246d14..7f37b6fe6c6 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -124,6 +124,9 @@ $result =
   $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM tab_ins");
 is($result, qq(1002), 'check initial data was copied to subscriber');
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_ins SELECT generate_series(1,50)");
 $node_publisher->safe_psql('postgres', "DELETE FROM tab_ins WHERE a > 20");
@@ -157,6 +160,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup('tap_sub');
 
+# Verify that plugin_filtered_bytes increases due to filtered update and delete
+# operations on tab_ins.  We cannot test the exact value since it may include
+# changes from other concurrent transactions.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after DML filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab_ins");
 is($result, qq(1052|1|1002), 'check replicated inserts on subscriber');
diff --git a/src/test/subscription/t/010_truncate.pl b/src/test/subscription/t/010_truncate.pl
index 3d16c2a800d..c41ad317221 100644
--- a/src/test/subscription/t/010_truncate.pl
+++ b/src/test/subscription/t/010_truncate.pl
@@ -69,6 +69,9 @@ $node_subscriber->safe_psql('postgres',
 # Wait for initial sync of all subscriptions
 $node_subscriber->wait_for_subscription_sync;
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+
 # insert data to truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -98,6 +101,16 @@ $node_publisher->wait_for_catchup('sub1');
 $result = $node_subscriber->safe_psql('postgres', "SELECT nextval('seq1')");
 is($result, qq(101), 'truncate restarted identities');
 
+# All the DMLs above happen on tables that are subscribed to by sub1 and not
+# sub2. plugin_filtered_bytes should get incremented for replication slot
+# corresponding to the subscription sub2. We can not test the exact value of
+# plugin_filtered_bytes because the counter is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after publication level filtering');
+$initial_filtered_bytes = $final_filtered_bytes;
+
 # test publication that does not replicate truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -107,6 +120,13 @@ $node_publisher->safe_psql('postgres', "TRUNCATE tab2");
 
 $node_publisher->wait_for_catchup('sub2');
 
+# Truncate changes are filtered out at publication level itself. Make sure that
+# the plugin_filtered_bytes is incremented.
+$final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after truncate filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab2");
 is($result, qq(3|1|3), 'truncate not replicated');
diff --git a/src/test/subscription/t/028_row_filter.pl b/src/test/subscription/t/028_row_filter.pl
index e2c83670053..039bf5ff5a0 100644
--- a/src/test/subscription/t/028_row_filter.pl
+++ b/src/test/subscription/t/028_row_filter.pl
@@ -579,6 +579,9 @@ is($result, qq(3|6),
 # commands are for testing normal logical replication behavior.
 #
 # test row filter (INSERT, UPDATE, DELETE)
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_rowfilter_1 (a, b) VALUES (800, 'test 800')");
 $node_publisher->safe_psql('postgres',
@@ -612,6 +615,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup($appname);
 
+# The changes which do not pass the row filter will be filtered. Make sure that
+# the plugin_filtered_bytes reflects that. We can not test the exact value of
+# plugin_filtered_bytes since it is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after row filtering');
+
 # Check expected replicated rows for tab_rowfilter_2
 # tap_pub_1 filter is: (c % 2 = 0)
 # tap_pub_2 filter is: (c % 3 = 0)
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 43fe3bcd593..9e47d1ebe0e 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1833,6 +1833,7 @@ OuterJoinClauseInfo
 OutputPluginCallbacks
 OutputPluginOptions
 OutputPluginOutputType
+OutputPluginStats
 OverridingKind
 PACE_HEADER
 PACL

base-commit: 14ee8e6403001c3788f2622cdcf81a8451502dc2
-- 
2.34.1

From 287217cf4aefeee0461bb77aa3377804752bc6e0 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Tue, 28 Oct 2025 12:42:04 +0530
Subject: [PATCH 2/2] Address Shveta's comments

---
 src/backend/replication/logical/logicalfuncs.c | 6 +++++-
 src/include/replication/output_plugin.h        | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index d2ab41de438..55e02e7ee21 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -65,6 +65,7 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	Datum		values[3];
 	bool		nulls[3];
 	DecodingOutputState *p;
+	int64		sentBytes = 0;
 
 	/* SQL Datums can only be of a limited length... */
 	if (ctx->out->len > MaxAllocSize - VARHDRSZ)
@@ -74,7 +75,9 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 
 	memset(nulls, 0, sizeof(nulls));
 	values[0] = LSNGetDatum(lsn);
+	sentBytes += sizeof(XLogRecPtr);
 	values[1] = TransactionIdGetDatum(xid);
+	sentBytes += sizeof(TransactionId);
 
 	/*
 	 * Assert ctx->out is in database encoding when we're writing textual
@@ -87,6 +90,7 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 
 	/* ick, but cstring_to_text_with_len works for bytea perfectly fine */
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
+	sentBytes += ctx->out->len;
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
 
@@ -95,7 +99,7 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	 * data sent downstream.
 	 */
 	if (ctx->stats)
-		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
+		ctx->stats->sentBytes += sentBytes;
 
 	p->returned_rows++;
 }
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 02018f0593c..4cc939e6c98 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -38,7 +38,7 @@ typedef struct OutputPluginStats
 	int64		sentTxns;		/* number of transactions decoded and sent
 								 * downstream */
 	int64		sentBytes;		/* amount of data decoded and sent downstream */
-	int64		filteredBytes;	/* amount of data from reoder buffer that was
+	int64		filteredBytes;	/* amount of data from reorder buffer that was
 								 * filtered out by the output plugin */
 } OutputPluginStats;
 
-- 
2.34.1

From e353db4c93be08371c6a949d86c33c5bad41bb78 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH 1/2] Report output plugin statistics in
 pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output plugin statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- plugin_filtered_bytes is the amount of changes filtered out by the
  output plugin
- plugin_sent_txns is the amount of transactions sent downstream by the
  output plugin
- plugin_sent_bytes is the amount of data sent downstream by the output
  plugin.

The prefix "plugin_" indicates that these counters are related to and
maintained by the output plugin. An output plugin may choose not to
initialize LogicalDecodingContext::stats, which holds these counters, in
which case the above columns will be reported as NULL.

When the stats are disabled after being enabled for a while, the plugin
stats are reset to 0, rather than carrying over the stale stats from the
time when the plugin was supporting the stats. This does not matter if
the plugin continues not to support statistics forever. But in case it
was supporting the stats once, discontinued doing so at some point in
time and then starts supporting the stats later, accumulating the new
stats based on the earlier accumulated stats could be misleading.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Additionally report name of the output plugin in the view for an easy
reference.

total_bytes and total_txns are the only fields remaining unqualified -
they do not convey what those bytes and txns are. Hence rename them
total_wal_bytes and total_wal_txns respectively to indicate that those
counts come from WAL stream.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Shveta Malik <shveta.malik@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++++---------
 contrib/test_decoding/sql/stats.sql           | 16 ++--
 contrib/test_decoding/t/001_repl_stats.pl     | 22 ++++--
 contrib/test_decoding/test_decoding.c         |  2 +
 doc/src/sgml/logicaldecoding.sgml             | 36 +++++++++
 doc/src/sgml/monitoring.sgml                  | 70 +++++++++++++++--
 src/backend/catalog/system_views.sql          |  8 +-
 src/backend/replication/logical/logical.c     | 28 ++++++-
 .../replication/logical/logicalfuncs.c        |  8 ++
 .../replication/logical/reorderbuffer.c       |  3 +-
 src/backend/replication/pgoutput/pgoutput.c   | 21 +++++
 src/backend/replication/walsender.c           |  7 ++
 src/backend/utils/activity/pgstat_replslot.c  | 19 ++++-
 src/backend/utils/adt/pgstatfuncs.c           | 34 ++++++--
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  8 +-
 src/include/replication/logical.h             |  1 +
 src/include/replication/output_plugin.h       | 13 ++++
 src/include/replication/reorderbuffer.h       |  1 +
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 .../t/035_standby_logical_decoding.pl         |  4 +-
 src/test/regress/expected/rules.out           | 10 ++-
 src/test/subscription/t/001_rep_changes.pl    | 11 +++
 src/test/subscription/t/010_truncate.pl       | 20 +++++
 src/test/subscription/t/028_row_filter.pl     | 11 +++
 src/tools/pgindent/typedefs.list              |  1 +
 26 files changed, 360 insertions(+), 89 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index 28da9123cc8..0e5c5fa5b18 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | t          | t           | t
- regression_slot_stats2 | t          | t           | t          | t           | t
- regression_slot_stats3 | t          | t           | t          | t           | t
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------+--------------------
+ regression_slot_stats1 | t          | t           | t              | t               |                1 | t          | t              | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t              | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t              | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | f          | f           | t
- regression_slot_stats2 | t          | t           | t          | t           | t
- regression_slot_stats3 | t          | t           | t          | t           | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------+--------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |            |                | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t              | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t              | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | f          | f           | t
- regression_slot_stats2 | t          | t           | f          | f           | t
- regression_slot_stats3 | t          | t           | f          | f           | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+------------------+-------------------+-----------------------+--------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |                   |                       | t
+ regression_slot_stats2 | t          | t           | f              | f               |                  |                   |                       | t
+ regression_slot_stats3 | t          | t           | f              | f               |                  |                   |                       | t
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count,
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index 6661dbcb85c..d6bf3cde8b1 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,22 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +52,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count,
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..756fc691ed6 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, plugin_filtered_bytes may be greater than 0. But it's not
+	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
-		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+		SELECT slot_name, total_wal_txns > 0 AS total_txn,
+			   total_wal_bytes > 0 AS total_bytes,
+			   plugin_sent_txns > 0 AS sent_txn,
+			   plugin_sent_bytes > 0 AS sent_bytes,
+			   plugin_filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -65,7 +71,7 @@ $node->poll_query_until(
 	'postgres', qq[
 	SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
 	WHERE slot_name ~ 'regression_slot'
-	AND total_txns > 0 AND total_bytes > 0;
+	AND total_wal_txns > 0 AND total_wal_bytes > 0;
 ]) or die "Timed out while waiting for statistics to be updated";
 
 # Test to drop one of the replication slot and verify replication statistics data is
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index 36e77c69e1c..d06f6c3f92b 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -173,6 +173,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	data->only_local = false;
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
 	opt->receive_rewrites = false;
@@ -310,6 +311,7 @@ static void
 pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
 {
 	OutputPluginPrepareWrite(ctx, last_write);
+	ctx->stats->sentTxns++;
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
 	else
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index b803a819cf1..0bf9ffbfd28 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -938,6 +938,42 @@ typedef struct OutputPluginOptions
       needs to have a state, it can
       use <literal>ctx-&gt;output_plugin_private</literal> to store it.
      </para>
+
+     <para>
+      The startup callback may initialize <literal>ctx-&gt;stats</literal>,
+      typically as follows, if it chooses to maintain and report statistics
+      about its activity in <structname>pg_stat_replication_slots</structname>.
+<programlisting>
+ctx->stats = palloc0(sizeof(OutputPluginStats));
+</programlisting>
+      where <literal>OutputPluginStats</literal> is defined as follows:
+<programlisting>
+typedef struct OutputPluginStats
+{
+      int64   sentTxns;
+      int64   sentBytes;
+      int64   filteredBytes;
+} OutputPluginStats;
+</programlisting>
+      <literal>sentTxns</literal> is the number of transactions sent downstream
+      by the output plugin. <literal>sentBytes</literal> is the amount of data,
+      in bytes, sent downstream by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that
+      are filtered out by the output plugin.
+      <function>OutputPluginWrite</function> will update
+      <literal>sentBytes</literal> if <literal>ctx-&gt;stats</literal> is
+      initialized by the output plugin. Function
+      <literal>ReorderBufferChangeSize</literal> may be used to find the size of
+      filtered <literal>ReorderBufferChange</literal>.
+     </para>
+
+     <note>
+      <para>
+       Once a plugin starts reporting and maintaining these statistics, it is
+       not expected that they will discontinue doing so. If they do, the result
+       may be misleading because of the cumulative nature of these statistics.
+      </para>
+     </note>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index d5f0fb7ba7c..1ccf781f45e 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1549,6 +1549,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1637,19 +1648,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_txns</structfield> <type>bigint</type>
+        <structfield>total_wal_txns</structfield> <type>bigint</type>
        </para>
        <para>
-        Number of decoded transactions sent to the decoding output plugin for
-        this slot. This counts top-level transactions only, and is not incremented
-        for subtransactions. Note that this includes the transactions that are
-        streamed and/or spilled.
+        Number of decoded transactions from WAL sent to the decoding output
+        plugin for this slot. This counts top-level transactions only, and is
+        not incremented for subtransactions. Note that this includes the
+        transactions that are streamed and/or spilled.
        </para></entry>
      </row>
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_bytes</structfield><type>bigint</type>
+        <structfield>total_wal_bytes</structfield><type>bigint</type>
        </para>
        <para>
         Amount of transaction data decoded for sending transactions to the
@@ -1659,6 +1670,53 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is sent to
+        the output plugin, e.g. the changes filtered by origin. The counter is
+        maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>. It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transactions sent to
+        the decoding plugin. Hence this count is expected to be less than or
+        equal to <structfield>total_wal_txns</structfield>.  The counter is maintained
+        by the output plugin mentioned in <structfield>plugin</structfield>.  It
+        is NULL when statistics is not initialized or immediately after a reset or
+        when not maintained by the output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes sent downstream for this slot by the
+        output plugin after applying filtering and converting into its output
+        format. The counter is maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>.  It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 823776c1498..be91e9b01e4 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1067,6 +1067,7 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
@@ -1074,8 +1075,11 @@ CREATE VIEW pg_stat_replication_slots AS
             s.stream_count,
             s.stream_bytes,
             s.mem_exceeded_count,
-            s.total_txns,
-            s.total_bytes,
+            s.total_wal_txns,
+            s.total_wal_bytes,
+            s.plugin_filtered_bytes,
+            s.plugin_sent_txns,
+            s.plugin_sent_bytes,
             s.stats_reset
     FROM pg_replication_slots as r,
         LATERAL pg_stat_get_replication_slot(slot_name) as s
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 93ed2eb368e..f0810f05153 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1952,6 +1952,7 @@ void
 UpdateDecodingStats(LogicalDecodingContext *ctx)
 {
 	ReorderBuffer *rb = ctx->reorder;
+	OutputPluginStats *stats = ctx->stats;
 	PgStat_StatReplSlotEntry repSlotStat;
 
 	/* Nothing to do if we don't have any replication stats to be sent. */
@@ -1959,7 +1960,7 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		rb->memExceededCount <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " (%s) %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1969,7 +1970,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamBytes,
 		 rb->memExceededCount,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 stats ? "plugin has stats" : "plugin has no stats",
+		 stats ? stats->sentTxns : 0,
+		 stats ? stats->sentBytes : 0,
+		 stats ? stats->filteredBytes : 0);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1978,8 +1983,17 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_count = rb->streamCount;
 	repSlotStat.stream_bytes = rb->streamBytes;
 	repSlotStat.mem_exceeded_count = rb->memExceededCount;
-	repSlotStat.total_txns = rb->totalTxns;
-	repSlotStat.total_bytes = rb->totalBytes;
+	repSlotStat.total_wal_txns = rb->totalTxns;
+	repSlotStat.total_wal_bytes = rb->totalBytes;
+	if (stats)
+	{
+		repSlotStat.plugin_has_stats = true;
+		repSlotStat.plugin_sent_txns = stats->sentTxns;
+		repSlotStat.plugin_sent_bytes = stats->sentBytes;
+		repSlotStat.plugin_filtered_bytes = stats->filteredBytes;
+	}
+	else
+		repSlotStat.plugin_has_stats = false;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1992,6 +2006,12 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->memExceededCount = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	if (stats)
+	{
+		stats->sentTxns = 0;
+		stats->sentBytes = 0;
+		stats->filteredBytes = 0;
+	}
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 25f890ddeed..d2ab41de438 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -89,6 +89,14 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/*
+	 * If output plugin has chosen to maintain its stats, update the amount of
+	 * data sent downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + sizeof(XLogRecPtr) + sizeof(TransactionId);
+
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index b57aef9916d..d336ef3a51f 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -4458,7 +4457,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 942e1abdb58..4b35f2de6aa 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -473,6 +473,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	MemoryContextRegisterResetCallback(ctx->context, mcallback);
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	/* This plugin uses binary protocol. */
 	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
@@ -614,6 +615,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	OutputPluginPrepareWrite(ctx, !send_replication_origin);
 	logicalrep_write_begin(ctx->out, txn);
 	txndata->sent_begin_txn = true;
+	ctx->stats->sentTxns++;
 
 	send_repl_origin(ctx, txn->origin_id, txn->origin_lsn,
 					 send_replication_origin);
@@ -1492,7 +1494,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TupleTableSlot *new_slot = NULL;
 
 	if (!is_publishable_relation(relation))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		return;
+	}
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1510,15 +1515,24 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1528,6 +1542,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
 			}
 			break;
@@ -1583,7 +1598,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		goto cleanup;
+	}
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1711,6 +1729,9 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
 	}
+	else
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
+
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 548eafa7a73..b0a5d4da7a7 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1587,6 +1587,13 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/*
+	 * If output plugin maintains statistics, update the amount of data sent
+	 * downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + 1; /* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index d210c261ac6..42ca13bd76a 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -88,6 +88,7 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
+#define REPLSLOT_SET_TO_ZERO(fld) statent->fld = 0
 	REPLSLOT_ACC(spill_txns);
 	REPLSLOT_ACC(spill_count);
 	REPLSLOT_ACC(spill_bytes);
@@ -95,9 +96,23 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_count);
 	REPLSLOT_ACC(stream_bytes);
 	REPLSLOT_ACC(mem_exceeded_count);
-	REPLSLOT_ACC(total_txns);
-	REPLSLOT_ACC(total_bytes);
+	REPLSLOT_ACC(total_wal_txns);
+	REPLSLOT_ACC(total_wal_bytes);
+	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
+	if (repSlotStat->plugin_has_stats)
+	{
+		REPLSLOT_ACC(plugin_sent_txns);
+		REPLSLOT_ACC(plugin_sent_bytes);
+		REPLSLOT_ACC(plugin_filtered_bytes);
+	}
+	else
+	{
+		REPLSLOT_SET_TO_ZERO(plugin_sent_txns);
+		REPLSLOT_SET_TO_ZERO(plugin_sent_bytes);
+		REPLSLOT_SET_TO_ZERO(plugin_filtered_bytes);
+	}
 #undef REPLSLOT_ACC
+#undef REPLSLOT_SET_TO_ZERO
 
 	pgstat_unlock_entry(entry_ref);
 }
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 1fe33df2756..be8d30ca9c6 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2121,7 +2121,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 11
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 14
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2148,11 +2148,17 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "mem_exceeded_count",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_txns",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_wal_txns",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "total_bytes",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "total_wal_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "plugin_filtered_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "plugin_sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "plugin_sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 14, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2176,13 +2182,25 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[5] = Int64GetDatum(slotent->stream_count);
 	values[6] = Int64GetDatum(slotent->stream_bytes);
 	values[7] = Int64GetDatum(slotent->mem_exceeded_count);
-	values[8] = Int64GetDatum(slotent->total_txns);
-	values[9] = Int64GetDatum(slotent->total_bytes);
+	values[8] = Int64GetDatum(slotent->total_wal_txns);
+	values[9] = Int64GetDatum(slotent->total_wal_bytes);
+	if (slotent->plugin_has_stats)
+	{
+		values[10] = Int64GetDatum(slotent->plugin_filtered_bytes);
+		values[11] = Int64GetDatum(slotent->plugin_sent_txns);
+		values[12] = Int64GetDatum(slotent->plugin_sent_bytes);
+	}
+	else
+	{
+		nulls[10] = true;
+		nulls[11] = true;
+		nulls[12] = true;
+	}
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[10] = true;
+		nulls[13] = true;
 	else
-		values[10] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[13] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index eecb43ec6f0..11404660a56 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5691,9 +5691,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,mem_exceeded_count,total_txns,total_bytes,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,mem_exceeded_count,total_wal_txns,total_wal_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index bc8077cbae6..ae11f39dd3b 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -396,8 +396,12 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_count;
 	PgStat_Counter stream_bytes;
 	PgStat_Counter mem_exceeded_count;
-	PgStat_Counter total_txns;
-	PgStat_Counter total_bytes;
+	PgStat_Counter total_wal_txns;
+	PgStat_Counter total_wal_bytes;
+	bool		plugin_has_stats;
+	PgStat_Counter plugin_sent_txns;
+	PgStat_Counter plugin_sent_bytes;
+	PgStat_Counter plugin_filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 2e562bee5a9..010c59f783d 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -52,6 +52,7 @@ typedef struct LogicalDecodingContext
 
 	OutputPluginCallbacks callbacks;
 	OutputPluginOptions options;
+	OutputPluginStats *stats;
 
 	/*
 	 * User specified options
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..02018f0593c 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -29,6 +29,19 @@ typedef struct OutputPluginOptions
 	bool		receive_rewrites;
 } OutputPluginOptions;
 
+/*
+ * Statistics about the transactions decoded and sent downstream by the output
+ * plugin.
+ */
+typedef struct OutputPluginStats
+{
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data from reoder buffer that was
+								 * filtered out by the output plugin */
+} OutputPluginStats;
+
 /*
  * Type of the shared library symbol _PG_output_plugin_init that is looked up
  * when loading an output plugin shared library.
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 3cbe106a3c7..382eba66a76 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -718,6 +718,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index f6c0a5bf649..be564b53bc6 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -215,10 +215,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_wal_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -236,10 +236,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_wal_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_wal_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index ebe2fae1789..5f4df30d65a 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -577,7 +577,7 @@ $node_primary->safe_psql('testdb',
 	qq[INSERT INTO decoding_test(x,y) SELECT 100,'100';]);
 
 $node_standby->poll_query_until('testdb',
-	qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+	qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 ) or die "replication slot stats of vacuum_full_activeslot not updated";
 
 # This should trigger the conflict
@@ -605,7 +605,7 @@ ok( $stderr =~
 # Ensure that replication slot stats are not removed after invalidation.
 is( $node_standby->safe_psql(
 		'testdb',
-		qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+		qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 	),
 	't',
 	'replication slot stats not removed after invalidation');
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 16753b2e4c0..d77059ae186 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2142,6 +2142,7 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
@@ -2149,11 +2150,14 @@ pg_stat_replication_slots| SELECT s.slot_name,
     s.stream_count,
     s.stream_bytes,
     s.mem_exceeded_count,
-    s.total_txns,
-    s.total_bytes,
+    s.total_wal_txns,
+    s.total_wal_bytes,
+    s.plugin_filtered_bytes,
+    s.plugin_sent_txns,
+    s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, mem_exceeded_count, total_txns, total_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, mem_exceeded_count, total_wal_txns, total_wal_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index 430c1246d14..7f37b6fe6c6 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -124,6 +124,9 @@ $result =
   $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM tab_ins");
 is($result, qq(1002), 'check initial data was copied to subscriber');
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_ins SELECT generate_series(1,50)");
 $node_publisher->safe_psql('postgres', "DELETE FROM tab_ins WHERE a > 20");
@@ -157,6 +160,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup('tap_sub');
 
+# Verify that plugin_filtered_bytes increases due to filtered update and delete
+# operations on tab_ins.  We cannot test the exact value since it may include
+# changes from other concurrent transactions.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after DML filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab_ins");
 is($result, qq(1052|1|1002), 'check replicated inserts on subscriber');
diff --git a/src/test/subscription/t/010_truncate.pl b/src/test/subscription/t/010_truncate.pl
index 3d16c2a800d..c41ad317221 100644
--- a/src/test/subscription/t/010_truncate.pl
+++ b/src/test/subscription/t/010_truncate.pl
@@ -69,6 +69,9 @@ $node_subscriber->safe_psql('postgres',
 # Wait for initial sync of all subscriptions
 $node_subscriber->wait_for_subscription_sync;
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+
 # insert data to truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -98,6 +101,16 @@ $node_publisher->wait_for_catchup('sub1');
 $result = $node_subscriber->safe_psql('postgres', "SELECT nextval('seq1')");
 is($result, qq(101), 'truncate restarted identities');
 
+# All the DMLs above happen on tables that are subscribed to by sub1 and not
+# sub2. plugin_filtered_bytes should get incremented for replication slot
+# corresponding to the subscription sub2. We can not test the exact value of
+# plugin_filtered_bytes because the counter is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after publication level filtering');
+$initial_filtered_bytes = $final_filtered_bytes;
+
 # test publication that does not replicate truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -107,6 +120,13 @@ $node_publisher->safe_psql('postgres', "TRUNCATE tab2");
 
 $node_publisher->wait_for_catchup('sub2');
 
+# Truncate changes are filtered out at publication level itself. Make sure that
+# the plugin_filtered_bytes is incremented.
+$final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after truncate filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab2");
 is($result, qq(3|1|3), 'truncate not replicated');
diff --git a/src/test/subscription/t/028_row_filter.pl b/src/test/subscription/t/028_row_filter.pl
index e2c83670053..039bf5ff5a0 100644
--- a/src/test/subscription/t/028_row_filter.pl
+++ b/src/test/subscription/t/028_row_filter.pl
@@ -579,6 +579,9 @@ is($result, qq(3|6),
 # commands are for testing normal logical replication behavior.
 #
 # test row filter (INSERT, UPDATE, DELETE)
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_rowfilter_1 (a, b) VALUES (800, 'test 800')");
 $node_publisher->safe_psql('postgres',
@@ -612,6 +615,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup($appname);
 
+# The changes which do not pass the row filter will be filtered. Make sure that
+# the plugin_filtered_bytes reflects that. We can not test the exact value of
+# plugin_filtered_bytes since it is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after row filtering');
+
 # Check expected replicated rows for tab_rowfilter_2
 # tap_pub_1 filter is: (c % 2 = 0)
 # tap_pub_2 filter is: (c % 3 = 0)
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index bb4e1b37005..66678b11066 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1832,6 +1832,7 @@ OuterJoinClauseInfo
 OutputPluginCallbacks
 OutputPluginOptions
 OutputPluginOutputType
+OutputPluginStats
 OverridingKind
 PACE_HEADER
 PACL

base-commit: 3e8e05596a020f043f1efd6406e4511ea85170bd
-- 
2.34.1

From 3d20178fc66d4a0c105890a139c5d5e7ca618a68 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH] Report output plugin statistics in pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output plugin statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- plugin_filtered_bytes is the amount of changes filtered out by the
  output plugin
- plugin_sent_txns is the amount of transactions sent downstream by the
  output plugin
- plugin_sent_bytes is the amount of data sent downstream by the output
  plugin.

The prefix "plugin_" indicates that these counters are related to and
maintained by the output plugin. An output plugin may choose not to
initialize LogicalDecodingContext::stats, which holds these counters, in
which case the above columns will be reported as NULL.

When the stats are disabled after being enabled for a while, the plugin
stats are reset to 0, rather than carrying over the stale stats from the
time when the plugin was supporting the stats. This does not matter if
the plugin continues not to support statistics forever. But in case it
was supporting the stats once, discontinued doing so at some point in
time and then starts supporting the stats later, accumulating the new
stats based on the earlier accumulated stats could be misleading.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Additionally report name of the output plugin in the view for an easy
reference.

total_bytes and total_txns are the only fields remaining unqualified -
they do not convey what those bytes and txns are. Hence rename them
total_wal_bytes and total_wal_txns respectively to indicate that those
counts come from WAL stream.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Shveta Malik <shveta.malik@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++++---------
 contrib/test_decoding/sql/stats.sql           | 16 ++--
 contrib/test_decoding/t/001_repl_stats.pl     | 22 ++++--
 contrib/test_decoding/test_decoding.c         |  2 +
 doc/src/sgml/logicaldecoding.sgml             | 36 +++++++++
 doc/src/sgml/monitoring.sgml                  | 70 +++++++++++++++--
 src/backend/catalog/system_views.sql          |  8 +-
 src/backend/replication/logical/logical.c     | 28 ++++++-
 .../replication/logical/logicalfuncs.c        | 12 +++
 .../replication/logical/reorderbuffer.c       |  3 +-
 src/backend/replication/pgoutput/pgoutput.c   | 33 +++++++-
 src/backend/replication/walsender.c           |  7 ++
 src/backend/utils/activity/pgstat_replslot.c  | 19 ++++-
 src/backend/utils/adt/pgstatfuncs.c           | 34 ++++++--
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  8 +-
 src/include/replication/logical.h             |  1 +
 src/include/replication/output_plugin.h       | 13 ++++
 src/include/replication/reorderbuffer.h       |  1 +
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 .../t/035_standby_logical_decoding.pl         |  4 +-
 src/test/regress/expected/rules.out           | 10 ++-
 src/test/subscription/t/001_rep_changes.pl    | 11 +++
 src/test/subscription/t/010_truncate.pl       | 20 +++++
 src/test/subscription/t/028_row_filter.pl     | 11 +++
 src/tools/pgindent/typedefs.list              |  1 +
 26 files changed, 375 insertions(+), 90 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index 28da9123cc8..0e5c5fa5b18 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | t          | t           | t
- regression_slot_stats2 | t          | t           | t          | t           | t
- regression_slot_stats3 | t          | t           | t          | t           | t
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------+--------------------
+ regression_slot_stats1 | t          | t           | t              | t               |                1 | t          | t              | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t              | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t              | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | f          | f           | t
- regression_slot_stats2 | t          | t           | t          | t           | t
- regression_slot_stats3 | t          | t           | t          | t           | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | sent_bytes | filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+------------------+------------+----------------+--------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |            |                | t
+ regression_slot_stats2 | t          | t           | t              | t               |                1 | t          | t              | t
+ regression_slot_stats3 | t          | t           | t              | t               |                1 | t          | t              | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | f          | f           | t
- regression_slot_stats2 | t          | t           | f          | f           | t
- regression_slot_stats3 | t          | t           | f          | f           | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | plugin_sent_txns | plugin_sent_bytes | plugin_filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+------------------+-------------------+-----------------------+--------------------
+ regression_slot_stats1 | t          | t           | f              | f               |                  |                   |                       | t
+ regression_slot_stats2 | t          | t           | f              | f               |                  |                   |                       | t
+ regression_slot_stats3 | t          | t           | f              | f               |                  |                   |                       | t
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_txns | total_bytes | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+------------+-------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |          0 |           0 | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_wal_txns | total_wal_bytes | plugin_filtered_bytes | plugin_sent_txns | plugin_sent_bytes | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+----------------+-----------------+-----------------------+------------------+-------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |              0 |               0 |                       |                  |                   | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count,
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index 6661dbcb85c..d6bf3cde8b1 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,22 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+
+-- total_wal_txns may vary based on the background activity but plugin_sent_txns
+-- should always be 1 since the background transactions are always skipped.
+-- Filtered bytes would be set only when there's a change that was passed to the
+-- plugin but was filtered out. Depending upon the background transactions,
+-- filtered bytes may or may not be zero.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes > 0 AS sent_bytes, plugin_filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, plugin_sent_txns, plugin_sent_bytes, plugin_filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +52,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count,
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..756fc691ed6 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, plugin_filtered_bytes may be greater than 0. But it's not
+	# guaranteed that such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
-		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+		SELECT slot_name, total_wal_txns > 0 AS total_txn,
+			   total_wal_bytes > 0 AS total_bytes,
+			   plugin_sent_txns > 0 AS sent_txn,
+			   plugin_sent_bytes > 0 AS sent_bytes,
+			   plugin_filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -65,7 +71,7 @@ $node->poll_query_until(
 	'postgres', qq[
 	SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
 	WHERE slot_name ~ 'regression_slot'
-	AND total_txns > 0 AND total_bytes > 0;
+	AND total_wal_txns > 0 AND total_wal_bytes > 0;
 ]) or die "Timed out while waiting for statistics to be updated";
 
 # Test to drop one of the replication slot and verify replication statistics data is
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index 36e77c69e1c..d06f6c3f92b 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -173,6 +173,7 @@ pg_decode_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	data->only_local = false;
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	opt->output_type = OUTPUT_PLUGIN_TEXTUAL_OUTPUT;
 	opt->receive_rewrites = false;
@@ -310,6 +311,7 @@ static void
 pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBufferTXN *txn, bool last_write)
 {
 	OutputPluginPrepareWrite(ctx, last_write);
+	ctx->stats->sentTxns++;
 	if (data->include_xids)
 		appendStringInfo(ctx->out, "BEGIN %u", txn->xid);
 	else
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index b803a819cf1..0bf9ffbfd28 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -938,6 +938,42 @@ typedef struct OutputPluginOptions
       needs to have a state, it can
       use <literal>ctx-&gt;output_plugin_private</literal> to store it.
      </para>
+
+     <para>
+      The startup callback may initialize <literal>ctx-&gt;stats</literal>,
+      typically as follows, if it chooses to maintain and report statistics
+      about its activity in <structname>pg_stat_replication_slots</structname>.
+<programlisting>
+ctx->stats = palloc0(sizeof(OutputPluginStats));
+</programlisting>
+      where <literal>OutputPluginStats</literal> is defined as follows:
+<programlisting>
+typedef struct OutputPluginStats
+{
+      int64   sentTxns;
+      int64   sentBytes;
+      int64   filteredBytes;
+} OutputPluginStats;
+</programlisting>
+      <literal>sentTxns</literal> is the number of transactions sent downstream
+      by the output plugin. <literal>sentBytes</literal> is the amount of data,
+      in bytes, sent downstream by the output plugin.
+      <literal>filteredBytes</literal> is the size of changes, in bytes, that
+      are filtered out by the output plugin.
+      <function>OutputPluginWrite</function> will update
+      <literal>sentBytes</literal> if <literal>ctx-&gt;stats</literal> is
+      initialized by the output plugin. Function
+      <literal>ReorderBufferChangeSize</literal> may be used to find the size of
+      filtered <literal>ReorderBufferChange</literal>.
+     </para>
+
+     <note>
+      <para>
+       Once a plugin starts reporting and maintaining these statistics, it is
+       not expected that they will discontinue doing so. If they do, the result
+       may be misleading because of the cumulative nature of these statistics.
+      </para>
+     </note>
     </sect3>
 
     <sect3 id="logicaldecoding-output-plugin-shutdown">
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index f3bf527d5b4..7f30094b228 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1549,6 +1549,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1637,19 +1648,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_txns</structfield> <type>bigint</type>
+        <structfield>total_wal_txns</structfield> <type>bigint</type>
        </para>
        <para>
-        Number of decoded transactions sent to the decoding output plugin for
-        this slot. This counts top-level transactions only, and is not incremented
-        for subtransactions. Note that this includes the transactions that are
-        streamed and/or spilled.
+        Number of decoded transactions from WAL sent to the decoding output
+        plugin for this slot. This counts top-level transactions only, and is
+        not incremented for subtransactions. Note that this includes the
+        transactions that are streamed and/or spilled.
        </para></entry>
      </row>
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_bytes</structfield><type>bigint</type>
+        <structfield>total_wal_bytes</structfield><type>bigint</type>
        </para>
        <para>
         Amount of transaction data decoded for sending transactions to the
@@ -1659,6 +1670,53 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is sent to
+        the output plugin, e.g. the changes filtered by origin. The counter is
+        maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>. It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transactions sent to
+        the decoding plugin. Hence this count is expected to be less than or
+        equal to <structfield>total_wal_txns</structfield>.  The counter is maintained
+        by the output plugin mentioned in <structfield>plugin</structfield>.  It
+        is NULL when statistics is not initialized or immediately after a reset or
+        when not maintained by the output plugin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin_sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes sent downstream for this slot by the
+        output plugin after applying filtering and converting into its output
+        format. The counter is maintained by the output plugin mentioned in
+        <structfield>plugin</structfield>.  It is NULL when statistics is not
+        initialized or immediately after a reset or when not maintained by the
+        output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index dec8df4f8ee..defca1cf9ac 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1067,6 +1067,7 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
@@ -1074,8 +1075,11 @@ CREATE VIEW pg_stat_replication_slots AS
             s.stream_count,
             s.stream_bytes,
             s.mem_exceeded_count,
-            s.total_txns,
-            s.total_bytes,
+            s.total_wal_txns,
+            s.total_wal_bytes,
+            s.plugin_filtered_bytes,
+            s.plugin_sent_txns,
+            s.plugin_sent_bytes,
             s.stats_reset
     FROM pg_replication_slots as r,
         LATERAL pg_stat_get_replication_slot(slot_name) as s
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 93ed2eb368e..f0810f05153 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -1952,6 +1952,7 @@ void
 UpdateDecodingStats(LogicalDecodingContext *ctx)
 {
 	ReorderBuffer *rb = ctx->reorder;
+	OutputPluginStats *stats = ctx->stats;
 	PgStat_StatReplSlotEntry repSlotStat;
 
 	/* Nothing to do if we don't have any replication stats to be sent. */
@@ -1959,7 +1960,7 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		rb->memExceededCount <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " (%s) %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1969,7 +1970,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamBytes,
 		 rb->memExceededCount,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 stats ? "plugin has stats" : "plugin has no stats",
+		 stats ? stats->sentTxns : 0,
+		 stats ? stats->sentBytes : 0,
+		 stats ? stats->filteredBytes : 0);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1978,8 +1983,17 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_count = rb->streamCount;
 	repSlotStat.stream_bytes = rb->streamBytes;
 	repSlotStat.mem_exceeded_count = rb->memExceededCount;
-	repSlotStat.total_txns = rb->totalTxns;
-	repSlotStat.total_bytes = rb->totalBytes;
+	repSlotStat.total_wal_txns = rb->totalTxns;
+	repSlotStat.total_wal_bytes = rb->totalBytes;
+	if (stats)
+	{
+		repSlotStat.plugin_has_stats = true;
+		repSlotStat.plugin_sent_txns = stats->sentTxns;
+		repSlotStat.plugin_sent_bytes = stats->sentBytes;
+		repSlotStat.plugin_filtered_bytes = stats->filteredBytes;
+	}
+	else
+		repSlotStat.plugin_has_stats = false;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1992,6 +2006,12 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->memExceededCount = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	if (stats)
+	{
+		stats->sentTxns = 0;
+		stats->sentBytes = 0;
+		stats->filteredBytes = 0;
+	}
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 25f890ddeed..55e02e7ee21 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -65,6 +65,7 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	Datum		values[3];
 	bool		nulls[3];
 	DecodingOutputState *p;
+	int64		sentBytes = 0;
 
 	/* SQL Datums can only be of a limited length... */
 	if (ctx->out->len > MaxAllocSize - VARHDRSZ)
@@ -74,7 +75,9 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 
 	memset(nulls, 0, sizeof(nulls));
 	values[0] = LSNGetDatum(lsn);
+	sentBytes += sizeof(XLogRecPtr);
 	values[1] = TransactionIdGetDatum(xid);
+	sentBytes += sizeof(TransactionId);
 
 	/*
 	 * Assert ctx->out is in database encoding when we're writing textual
@@ -87,8 +90,17 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 
 	/* ick, but cstring_to_text_with_len works for bytea perfectly fine */
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
+	sentBytes += ctx->out->len;
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/*
+	 * If output plugin has chosen to maintain its stats, update the amount of
+	 * data sent downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += sentBytes;
+
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index b57aef9916d..d336ef3a51f 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -4458,7 +4457,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 942e1abdb58..367ba9efab3 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -473,6 +473,7 @@ pgoutput_startup(LogicalDecodingContext *ctx, OutputPluginOptions *opt,
 	MemoryContextRegisterResetCallback(ctx->context, mcallback);
 
 	ctx->output_plugin_private = data;
+	ctx->stats = palloc0(sizeof(OutputPluginStats));
 
 	/* This plugin uses binary protocol. */
 	opt->output_type = OUTPUT_PLUGIN_BINARY_OUTPUT;
@@ -614,6 +615,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 	OutputPluginPrepareWrite(ctx, !send_replication_origin);
 	logicalrep_write_begin(ctx->out, txn);
 	txndata->sent_begin_txn = true;
+	ctx->stats->sentTxns++;
 
 	send_repl_origin(ctx, txn->origin_id, txn->origin_lsn,
 					 send_replication_origin);
@@ -1492,7 +1494,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	TupleTableSlot *new_slot = NULL;
 
 	if (!is_publishable_relation(relation))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		return;
+	}
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1510,15 +1515,24 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
+			{
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
+			}
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1528,6 +1542,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
+				ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 				return;
 			}
 			break;
@@ -1583,7 +1598,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
 		goto cleanup;
+	}
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1603,7 +1621,11 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 
 	OutputPluginPrepareWrite(ctx, true);
 
-	/* Send the data */
+	/*
+	 * Send the data. Even if we end up filtering some columns while sending
+	 * the message, we won't filter the change, as a whole. Hence we don't
+	 * increment filteredBytes.
+	 */
 	switch (action)
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
@@ -1710,7 +1732,16 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.cascade,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
+
+		/*
+		 * Even if we filtered out some relations, we still send a TRUNCATE
+		 * message for the remaining relations. Since the change, as a whole,
+		 * is not filtered out we don't increment filteredBytes.
+		 */
 	}
+	else
+		ctx->stats->filteredBytes += ReorderBufferChangeSize(change);
+
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 548eafa7a73..b0a5d4da7a7 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1587,6 +1587,13 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/*
+	 * If output plugin maintains statistics, update the amount of data sent
+	 * downstream.
+	 */
+	if (ctx->stats)
+		ctx->stats->sentBytes += ctx->out->len + 1; /* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index d210c261ac6..42ca13bd76a 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -88,6 +88,7 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 
 	/* Update the replication slot statistics */
 #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
+#define REPLSLOT_SET_TO_ZERO(fld) statent->fld = 0
 	REPLSLOT_ACC(spill_txns);
 	REPLSLOT_ACC(spill_count);
 	REPLSLOT_ACC(spill_bytes);
@@ -95,9 +96,23 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_count);
 	REPLSLOT_ACC(stream_bytes);
 	REPLSLOT_ACC(mem_exceeded_count);
-	REPLSLOT_ACC(total_txns);
-	REPLSLOT_ACC(total_bytes);
+	REPLSLOT_ACC(total_wal_txns);
+	REPLSLOT_ACC(total_wal_bytes);
+	statent->plugin_has_stats = repSlotStat->plugin_has_stats;
+	if (repSlotStat->plugin_has_stats)
+	{
+		REPLSLOT_ACC(plugin_sent_txns);
+		REPLSLOT_ACC(plugin_sent_bytes);
+		REPLSLOT_ACC(plugin_filtered_bytes);
+	}
+	else
+	{
+		REPLSLOT_SET_TO_ZERO(plugin_sent_txns);
+		REPLSLOT_SET_TO_ZERO(plugin_sent_bytes);
+		REPLSLOT_SET_TO_ZERO(plugin_filtered_bytes);
+	}
 #undef REPLSLOT_ACC
+#undef REPLSLOT_SET_TO_ZERO
 
 	pgstat_unlock_entry(entry_ref);
 }
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a710508979e..672b01a246d 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2129,7 +2129,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 11
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 14
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2156,11 +2156,17 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "mem_exceeded_count",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_txns",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_wal_txns",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "total_bytes",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "total_wal_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "plugin_filtered_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "plugin_sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "plugin_sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 14, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2184,13 +2190,25 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[5] = Int64GetDatum(slotent->stream_count);
 	values[6] = Int64GetDatum(slotent->stream_bytes);
 	values[7] = Int64GetDatum(slotent->mem_exceeded_count);
-	values[8] = Int64GetDatum(slotent->total_txns);
-	values[9] = Int64GetDatum(slotent->total_bytes);
+	values[8] = Int64GetDatum(slotent->total_wal_txns);
+	values[9] = Int64GetDatum(slotent->total_wal_bytes);
+	if (slotent->plugin_has_stats)
+	{
+		values[10] = Int64GetDatum(slotent->plugin_filtered_bytes);
+		values[11] = Int64GetDatum(slotent->plugin_sent_txns);
+		values[12] = Int64GetDatum(slotent->plugin_sent_bytes);
+	}
+	else
+	{
+		nulls[10] = true;
+		nulls[11] = true;
+		nulls[12] = true;
+	}
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[10] = true;
+		nulls[13] = true;
 	else
-		values[10] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[13] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 9121a382f76..e78d4f0ab1e 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5691,9 +5691,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,mem_exceeded_count,total_txns,total_bytes,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,mem_exceeded_count,total_wal_txns,total_wal_bytes,plugin_filtered_bytes,plugin_sent_txns,plugin_sent_bytes,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 7ae503e71a2..427cf55d4b6 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -396,8 +396,12 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_count;
 	PgStat_Counter stream_bytes;
 	PgStat_Counter mem_exceeded_count;
-	PgStat_Counter total_txns;
-	PgStat_Counter total_bytes;
+	PgStat_Counter total_wal_txns;
+	PgStat_Counter total_wal_bytes;
+	bool		plugin_has_stats;
+	PgStat_Counter plugin_sent_txns;
+	PgStat_Counter plugin_sent_bytes;
+	PgStat_Counter plugin_filtered_bytes;
 	TimestampTz stat_reset_timestamp;
 } PgStat_StatReplSlotEntry;
 
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
index 2e562bee5a9..010c59f783d 100644
--- a/src/include/replication/logical.h
+++ b/src/include/replication/logical.h
@@ -52,6 +52,7 @@ typedef struct LogicalDecodingContext
 
 	OutputPluginCallbacks callbacks;
 	OutputPluginOptions options;
+	OutputPluginStats *stats;
 
 	/*
 	 * User specified options
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..4cc939e6c98 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -29,6 +29,19 @@ typedef struct OutputPluginOptions
 	bool		receive_rewrites;
 } OutputPluginOptions;
 
+/*
+ * Statistics about the transactions decoded and sent downstream by the output
+ * plugin.
+ */
+typedef struct OutputPluginStats
+{
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data from reorder buffer that was
+								 * filtered out by the output plugin */
+} OutputPluginStats;
+
 /*
  * Type of the shared library symbol _PG_output_plugin_init that is looked up
  * when loading an output plugin shared library.
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 3cbe106a3c7..382eba66a76 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -718,6 +718,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index 96b70b84d5e..49bfe679249 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -214,10 +214,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_wal_bytes > 0, plugin_sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -235,10 +235,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_wal_bytes = 0, plugin_sent_bytes is NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_wal_bytes and plugin_sent_bytes were set to 0 and NULL respectively.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index ebe2fae1789..5f4df30d65a 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -577,7 +577,7 @@ $node_primary->safe_psql('testdb',
 	qq[INSERT INTO decoding_test(x,y) SELECT 100,'100';]);
 
 $node_standby->poll_query_until('testdb',
-	qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+	qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 ) or die "replication slot stats of vacuum_full_activeslot not updated";
 
 # This should trigger the conflict
@@ -605,7 +605,7 @@ ok( $stderr =~
 # Ensure that replication slot stats are not removed after invalidation.
 is( $node_standby->safe_psql(
 		'testdb',
-		qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+		qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 	),
 	't',
 	'replication slot stats not removed after invalidation');
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 77e25ca029e..4bc5668f0fd 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2142,6 +2142,7 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
@@ -2149,11 +2150,14 @@ pg_stat_replication_slots| SELECT s.slot_name,
     s.stream_count,
     s.stream_bytes,
     s.mem_exceeded_count,
-    s.total_txns,
-    s.total_bytes,
+    s.total_wal_txns,
+    s.total_wal_bytes,
+    s.plugin_filtered_bytes,
+    s.plugin_sent_txns,
+    s.plugin_sent_bytes,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, mem_exceeded_count, total_txns, total_bytes, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, mem_exceeded_count, total_wal_txns, total_wal_bytes, plugin_filtered_bytes, plugin_sent_txns, plugin_sent_bytes, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index 430c1246d14..7f37b6fe6c6 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -124,6 +124,9 @@ $result =
   $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM tab_ins");
 is($result, qq(1002), 'check initial data was copied to subscriber');
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_ins SELECT generate_series(1,50)");
 $node_publisher->safe_psql('postgres', "DELETE FROM tab_ins WHERE a > 20");
@@ -157,6 +160,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup('tap_sub');
 
+# Verify that plugin_filtered_bytes increases due to filtered update and delete
+# operations on tab_ins.  We cannot test the exact value since it may include
+# changes from other concurrent transactions.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after DML filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab_ins");
 is($result, qq(1052|1|1002), 'check replicated inserts on subscriber');
diff --git a/src/test/subscription/t/010_truncate.pl b/src/test/subscription/t/010_truncate.pl
index 3d16c2a800d..c41ad317221 100644
--- a/src/test/subscription/t/010_truncate.pl
+++ b/src/test/subscription/t/010_truncate.pl
@@ -69,6 +69,9 @@ $node_subscriber->safe_psql('postgres',
 # Wait for initial sync of all subscriptions
 $node_subscriber->wait_for_subscription_sync;
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+
 # insert data to truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -98,6 +101,16 @@ $node_publisher->wait_for_catchup('sub1');
 $result = $node_subscriber->safe_psql('postgres', "SELECT nextval('seq1')");
 is($result, qq(101), 'truncate restarted identities');
 
+# All the DMLs above happen on tables that are subscribed to by sub1 and not
+# sub2. plugin_filtered_bytes should get incremented for replication slot
+# corresponding to the subscription sub2. We can not test the exact value of
+# plugin_filtered_bytes because the counter is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after publication level filtering');
+$initial_filtered_bytes = $final_filtered_bytes;
+
 # test publication that does not replicate truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -107,6 +120,13 @@ $node_publisher->safe_psql('postgres', "TRUNCATE tab2");
 
 $node_publisher->wait_for_catchup('sub2');
 
+# Truncate changes are filtered out at publication level itself. Make sure that
+# the plugin_filtered_bytes is incremented.
+$final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after truncate filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab2");
 is($result, qq(3|1|3), 'truncate not replicated');
diff --git a/src/test/subscription/t/028_row_filter.pl b/src/test/subscription/t/028_row_filter.pl
index e2c83670053..039bf5ff5a0 100644
--- a/src/test/subscription/t/028_row_filter.pl
+++ b/src/test/subscription/t/028_row_filter.pl
@@ -579,6 +579,9 @@ is($result, qq(3|6),
 # commands are for testing normal logical replication behavior.
 #
 # test row filter (INSERT, UPDATE, DELETE)
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT coalesce(plugin_filtered_bytes, 0) FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_rowfilter_1 (a, b) VALUES (800, 'test 800')");
 $node_publisher->safe_psql('postgres',
@@ -612,6 +615,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup($appname);
 
+# The changes which do not pass the row filter will be filtered. Make sure that
+# the plugin_filtered_bytes reflects that. We can not test the exact value of
+# plugin_filtered_bytes since it is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT plugin_filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'plugin_filtered_bytes increased after row filtering');
+
 # Check expected replicated rows for tab_rowfilter_2
 # tap_pub_1 filter is: (c % 2 = 0)
 # tap_pub_2 filter is: (c % 3 = 0)
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 018b5919cf6..3f1206a59c8 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1833,6 +1833,7 @@ OuterJoinClauseInfo
 OutputPluginCallbacks
 OutputPluginOptions
 OutputPluginOutputType
+OutputPluginStats
 OverridingKind
 PACE_HEADER
 PACL

base-commit: f242dbcede9cb1c2f60ca31e6ad1141e0713bc65
-- 
2.34.1

From f15d7ca6075f5364713582f7714d166c22b36e88 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Fri, 27 Jun 2025 09:16:23 +0530
Subject: [PATCH v20251211] Report output plugin statistics in
 pg_stat_replication_slots

As of now pg_stat_replication_slots reports statistics about the reorder
buffer, but it does not report output statistics like the amount of data
filtered by the output plugin, amount of data sent downstream or the
number of transactions sent downstream. This statistics is useful when
investigating issues related to a slow downstream.

This commit adds following fields to pg_stat_replication_slots
- filtered_bytes is the amount of changes filtered out by the
  output plugin
- sent_txns is the amount of transactions sent downstream by the
  output plugin
- sent_bytes is the amount of data sent downstream by the output
  plugin.

Filtered bytes are reported next to total_bytes to keep these two
closely related fields together.

Though these counts are stored and maintained by the core, they require
the output plugin to return correct values to the relevant callbacks.
This has been added as note in the documentation. In order to aid
debugging descripancies in these counter, name of the output plugin is
added to the view for an easy reference.

total_bytes and total_txns are the only fields remaining unqualified -
they do not convey what those bytes and txns are. Hence rename them
total_wal_bytes and total_wal_txns respectively to indicate that those
counts come from WAL stream.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Shveta Malik <shveta.malik@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Ashutosh Sharma <ashu.coek88@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAExHW5s6KntzUyUoMbKR5dgwRmdV2Ay_2+AnTgYGAzo=Qv61wA@mail.gmail.com
---
 contrib/test_decoding/expected/stats.out      | 77 ++++++++-------
 contrib/test_decoding/sql/stats.sql           | 16 +++-
 contrib/test_decoding/t/001_repl_stats.pl     | 22 +++--
 contrib/test_decoding/test_decoding.c         | 55 ++++++-----
 doc/src/sgml/logicaldecoding.sgml             | 96 ++++++++++++++-----
 doc/src/sgml/monitoring.sgml                  | 70 ++++++++++++--
 src/backend/catalog/system_views.sql          |  8 +-
 src/backend/replication/logical/logical.c     | 44 ++++++---
 .../replication/logical/logicalfuncs.c        |  8 ++
 .../replication/logical/reorderbuffer.c       |  6 +-
 src/backend/replication/pgoutput/pgoutput.c   | 65 +++++++++----
 src/backend/replication/walsender.c           |  3 +
 src/backend/utils/activity/pgstat_replslot.c  |  7 +-
 src/backend/utils/adt/pgstatfuncs.c           | 35 ++++---
 src/include/catalog/pg_proc.dat               |  6 +-
 src/include/pgstat.h                          |  7 +-
 src/include/replication/output_plugin.h       | 43 +++++----
 src/include/replication/reorderbuffer.h       |  6 ++
 src/test/recovery/t/006_logical_decoding.pl   | 12 +--
 .../t/035_standby_logical_decoding.pl         |  4 +-
 src/test/regress/expected/rules.out           | 10 +-
 src/test/subscription/t/001_rep_changes.pl    | 11 +++
 src/test/subscription/t/010_truncate.pl       | 20 ++++
 src/test/subscription/t/028_row_filter.pl     | 11 +++
 24 files changed, 452 insertions(+), 190 deletions(-)

diff --git a/contrib/test_decoding/expected/stats.out b/contrib/test_decoding/expected/stats.out
index a9ead3c41aa..54079b7d83d 100644
--- a/contrib/test_decoding/expected/stats.out
+++ b/contrib/test_decoding/expected/stats.out
@@ -37,12 +37,17 @@ SELECT pg_stat_force_next_flush();
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | t          | t           | t
- regression_slot_stats2 | t          | t           | t          | t           | t
- regression_slot_stats3 | t          | t           | t          | t           | t
+-- total_wal_txns may vary based on the background activity but sent_txns should
+-- always be 1 since the background transactions are always skipped. Usually we
+-- expect filtered_bytes to be 0 since the entire transaction executed by this
+-- test is replicated. But there may be some background transactions, changes
+-- from which are filtered out by the output plugin, so we check for >= 0 here.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, sent_txns, sent_bytes > 0 AS sent_bytes, filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | sent_txns | sent_bytes | filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+-----------+------------+----------------+--------------------
+ regression_slot_stats1 | t          | t           | t              | t               |         1 | t          | t              | t
+ regression_slot_stats2 | t          | t           | t              | t               |         1 | t          | t              | t
+ regression_slot_stats3 | t          | t           | t              | t               |         1 | t          | t              | t
 (3 rows)
 
 RESET logical_decoding_work_mem;
@@ -53,12 +58,12 @@ SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | f          | f           | t
- regression_slot_stats2 | t          | t           | t          | t           | t
- regression_slot_stats3 | t          | t           | t          | t           | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, sent_txns, sent_bytes > 0 AS sent_bytes, filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | sent_txns | sent_bytes | filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+-----------+------------+----------------+--------------------
+ regression_slot_stats1 | t          | t           | f              | f               |         0 | f          | t              | t
+ regression_slot_stats2 | t          | t           | t              | t               |         1 | t          | t              | t
+ regression_slot_stats3 | t          | t           | t              | t               |         1 | t          | t              | t
 (3 rows)
 
 -- reset stats for all slots
@@ -68,27 +73,27 @@ SELECT pg_stat_reset_replication_slot(NULL);
  
 (1 row)
 
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
-       slot_name        | spill_txns | spill_count | total_txns | total_bytes | mem_exceeded_count 
-------------------------+------------+-------------+------------+-------------+--------------------
- regression_slot_stats1 | t          | t           | f          | f           | t
- regression_slot_stats2 | t          | t           | f          | f           | t
- regression_slot_stats3 | t          | t           | f          | f           | t
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, sent_txns, sent_bytes, filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+       slot_name        | spill_txns | spill_count | total_wal_txns | total_wal_bytes | sent_txns | sent_bytes | filtered_bytes | mem_exceeded_count 
+------------------------+------------+-------------+----------------+-----------------+-----------+------------+----------------+--------------------
+ regression_slot_stats1 | t          | t           | f              | f               |         0 |          0 |              0 | t
+ regression_slot_stats2 | t          | t           | f              | f               |         0 |          0 |              0 | t
+ regression_slot_stats3 | t          | t           | f              | f               |         0 |          0 |              0 | t
 (3 rows)
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_txns | total_bytes | slotsync_skip_count | slotsync_last_skip | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+------------+-------------+---------------------+--------------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |          0 |           0 |                   0 |                    | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_wal_txns | total_wal_bytes | filtered_bytes | sent_txns | sent_bytes | slotsync_skip_count | slotsync_last_skip | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+----------------+-----------------+----------------+-----------+------------+---------------------+--------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |              0 |               0 |              0 |         0 |          0 |                   0 |                    | 
 (1 row)
 
 SELECT pg_stat_reset_replication_slot('do-not-exist');
 ERROR:  replication slot "do-not-exist" does not exist
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
-  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_txns | total_bytes | slotsync_skip_count | slotsync_last_skip | stats_reset 
---------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+------------+-------------+---------------------+--------------------+-------------
- do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |          0 |           0 |                   0 |                    | 
+  slot_name   | spill_txns | spill_count | spill_bytes | stream_txns | stream_count | stream_bytes | mem_exceeded_count | total_wal_txns | total_wal_bytes | filtered_bytes | sent_txns | sent_bytes | slotsync_skip_count | slotsync_last_skip | stats_reset 
+--------------+------------+-------------+-------------+-------------+--------------+--------------+--------------------+----------------+-----------------+----------------+-----------+------------+---------------------+--------------------+-------------
+ do-not-exist |          0 |           0 |           0 |           0 |            0 |            0 |                  0 |              0 |               0 |              0 |         0 |          0 |                   0 |                    | 
 (1 row)
 
 -- spilling the xact
@@ -121,20 +126,20 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count,
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
-SELECT slot_name FROM pg_stat_replication_slots;
-       slot_name        
-------------------------
- regression_slot_stats1
- regression_slot_stats2
- regression_slot_stats3
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+       slot_name        |    plugin     
+------------------------+---------------
+ regression_slot_stats1 | test_decoding
+ regression_slot_stats2 | test_decoding
+ regression_slot_stats3 | test_decoding
 (3 rows)
 
 COMMIT;
diff --git a/contrib/test_decoding/sql/stats.sql b/contrib/test_decoding/sql/stats.sql
index 6661dbcb85c..17e7c0e8f88 100644
--- a/contrib/test_decoding/sql/stats.sql
+++ b/contrib/test_decoding/sql/stats.sql
@@ -15,16 +15,22 @@ SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats1', NULL,
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats2', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT count(*) FROM pg_logical_slot_get_changes('regression_slot_stats3', NULL, NULL, 'skip-empty-xacts', '1');
 SELECT pg_stat_force_next_flush();
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+
+-- total_wal_txns may vary based on the background activity but sent_txns should
+-- always be 1 since the background transactions are always skipped. Usually we
+-- expect filtered_bytes to be 0 since the entire transaction executed by this
+-- test is replicated. But there may be some background transactions, changes
+-- from which are filtered out by the output plugin, so we check for >= 0 here.
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, sent_txns, sent_bytes > 0 AS sent_bytes, filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 RESET logical_decoding_work_mem;
 
 -- reset stats for one slot, others should be unaffected
 SELECT pg_stat_reset_replication_slot('regression_slot_stats1');
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, sent_txns, sent_bytes > 0 AS sent_bytes, filtered_bytes >= 0 AS filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- reset stats for all slots
 SELECT pg_stat_reset_replication_slot(NULL);
-SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_txns > 0 AS total_txns, total_bytes > 0 AS total_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
+SELECT slot_name, spill_txns = 0 AS spill_txns, spill_count = 0 AS spill_count, total_wal_txns > 0 AS total_wal_txns, total_wal_bytes > 0 AS total_wal_bytes, sent_txns, sent_bytes, filtered_bytes, mem_exceeded_count = 0 AS mem_exceeded_count FROM pg_stat_replication_slots ORDER BY slot_name;
 
 -- verify accessing/resetting stats for non-existent slot does something reasonable
 SELECT * FROM pg_stat_get_replication_slot('do-not-exist');
@@ -46,8 +52,8 @@ SELECT slot_name, spill_txns > 0 AS spill_txns, spill_count > 0 AS spill_count,
 -- Ensure stats can be repeatedly accessed using the same stats snapshot. See
 -- https://postgr.es/m/20210317230447.c7uc4g3vbs4wi32i%40alap3.anarazel.de
 BEGIN;
-SELECT slot_name FROM pg_stat_replication_slots;
-SELECT slot_name FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
+SELECT slot_name, plugin FROM pg_stat_replication_slots;
 COMMIT;
 
 
diff --git a/contrib/test_decoding/t/001_repl_stats.pl b/contrib/test_decoding/t/001_repl_stats.pl
index 0de62edb7d8..89d3ff0a239 100644
--- a/contrib/test_decoding/t/001_repl_stats.pl
+++ b/contrib/test_decoding/t/001_repl_stats.pl
@@ -23,10 +23,16 @@ sub test_slot_stats
 
 	my ($node, $expected, $msg) = @_;
 
+	# If there are background transactions which are filtered out by the output
+	# plugin, filtered_bytes may be greater than 0. But it's not guaranteed that
+	# such transactions would be present.
 	my $result = $node->safe_psql(
 		'postgres', qq[
-		SELECT slot_name, total_txns > 0 AS total_txn,
-			   total_bytes > 0 AS total_bytes
+		SELECT slot_name, total_wal_txns > 0 AS total_txn,
+			   total_wal_bytes > 0 AS total_bytes,
+			   sent_txns > 0 AS sent_txn,
+			   sent_bytes > 0 AS sent_bytes,
+			   filtered_bytes >= 0 AS filtered_bytes
 			   FROM pg_stat_replication_slots
 			   ORDER BY slot_name]);
 	is($result, $expected, $msg);
@@ -65,7 +71,7 @@ $node->poll_query_until(
 	'postgres', qq[
 	SELECT count(slot_name) >= 4 FROM pg_stat_replication_slots
 	WHERE slot_name ~ 'regression_slot'
-	AND total_txns > 0 AND total_bytes > 0;
+	AND total_wal_txns > 0 AND total_wal_bytes > 0;
 ]) or die "Timed out while waiting for statistics to be updated";
 
 # Test to drop one of the replication slot and verify replication statistics data is
@@ -80,9 +86,9 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t
-regression_slot3|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t
+regression_slot3|t|t|t|t|t),
 	'check replication statistics are updated');
 
 # Test to remove one of the replication slots and adjust
@@ -104,8 +110,8 @@ $node->start;
 # restart.
 test_slot_stats(
 	$node,
-	qq(regression_slot1|t|t
-regression_slot2|t|t),
+	qq(regression_slot1|t|t|t|t|t
+regression_slot2|t|t|t|t|t),
 	'check replication statistics after removing the slot file');
 
 # cleanup
diff --git a/contrib/test_decoding/test_decoding.c b/contrib/test_decoding/test_decoding.c
index 47094f86f5f..69ad9599804 100644
--- a/contrib/test_decoding/test_decoding.c
+++ b/contrib/test_decoding/test_decoding.c
@@ -60,12 +60,12 @@ static void pg_output_begin(LogicalDecodingContext *ctx,
 							TestDecodingData *data,
 							ReorderBufferTXN *txn,
 							bool last_write);
-static void pg_decode_commit_txn(LogicalDecodingContext *ctx,
+static bool pg_decode_commit_txn(LogicalDecodingContext *ctx,
 								 ReorderBufferTXN *txn, XLogRecPtr commit_lsn);
-static void pg_decode_change(LogicalDecodingContext *ctx,
+static bool pg_decode_change(LogicalDecodingContext *ctx,
 							 ReorderBufferTXN *txn, Relation relation,
 							 ReorderBufferChange *change);
-static void pg_decode_truncate(LogicalDecodingContext *ctx,
+static bool pg_decode_truncate(LogicalDecodingContext *ctx,
 							   ReorderBufferTXN *txn,
 							   int nrelations, Relation relations[],
 							   ReorderBufferChange *change);
@@ -80,7 +80,7 @@ static bool pg_decode_filter_prepare(LogicalDecodingContext *ctx,
 									 const char *gid);
 static void pg_decode_begin_prepare_txn(LogicalDecodingContext *ctx,
 										ReorderBufferTXN *txn);
-static void pg_decode_prepare_txn(LogicalDecodingContext *ctx,
+static bool pg_decode_prepare_txn(LogicalDecodingContext *ctx,
 								  ReorderBufferTXN *txn,
 								  XLogRecPtr prepare_lsn);
 static void pg_decode_commit_prepared_txn(LogicalDecodingContext *ctx,
@@ -98,16 +98,16 @@ static void pg_output_stream_start(LogicalDecodingContext *ctx,
 								   bool last_write);
 static void pg_decode_stream_stop(LogicalDecodingContext *ctx,
 								  ReorderBufferTXN *txn);
-static void pg_decode_stream_abort(LogicalDecodingContext *ctx,
+static bool pg_decode_stream_abort(LogicalDecodingContext *ctx,
 								   ReorderBufferTXN *txn,
 								   XLogRecPtr abort_lsn);
-static void pg_decode_stream_prepare(LogicalDecodingContext *ctx,
+static bool pg_decode_stream_prepare(LogicalDecodingContext *ctx,
 									 ReorderBufferTXN *txn,
 									 XLogRecPtr prepare_lsn);
-static void pg_decode_stream_commit(LogicalDecodingContext *ctx,
+static bool pg_decode_stream_commit(LogicalDecodingContext *ctx,
 									ReorderBufferTXN *txn,
 									XLogRecPtr commit_lsn);
-static void pg_decode_stream_change(LogicalDecodingContext *ctx,
+static bool pg_decode_stream_change(LogicalDecodingContext *ctx,
 									ReorderBufferTXN *txn,
 									Relation relation,
 									ReorderBufferChange *change);
@@ -115,7 +115,7 @@ static void pg_decode_stream_message(LogicalDecodingContext *ctx,
 									 ReorderBufferTXN *txn, XLogRecPtr lsn,
 									 bool transactional, const char *prefix,
 									 Size sz, const char *message);
-static void pg_decode_stream_truncate(LogicalDecodingContext *ctx,
+static bool pg_decode_stream_truncate(LogicalDecodingContext *ctx,
 									  ReorderBufferTXN *txn,
 									  int nrelations, Relation relations[],
 									  ReorderBufferChange *change);
@@ -318,7 +318,7 @@ pg_output_begin(LogicalDecodingContext *ctx, TestDecodingData *data, ReorderBuff
 }
 
 /* COMMIT callback */
-static void
+static bool
 pg_decode_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 					 XLogRecPtr commit_lsn)
 {
@@ -330,7 +330,7 @@ pg_decode_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	txn->output_plugin_private = NULL;
 
 	if (data->skip_empty_xacts && !xact_wrote_changes)
-		return;
+		return false;
 
 	OutputPluginPrepareWrite(ctx, true);
 	if (data->include_xids)
@@ -343,6 +343,7 @@ pg_decode_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 						 timestamptz_to_str(txn->commit_time));
 
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
 /* BEGIN PREPARE callback */
@@ -367,7 +368,7 @@ pg_decode_begin_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 }
 
 /* PREPARE callback */
-static void
+static bool
 pg_decode_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 					  XLogRecPtr prepare_lsn)
 {
@@ -379,7 +380,7 @@ pg_decode_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * where the first operation is received for this transaction.
 	 */
 	if (data->skip_empty_xacts && !txndata->xact_wrote_changes)
-		return;
+		return false;
 
 	OutputPluginPrepareWrite(ctx, true);
 
@@ -394,6 +395,7 @@ pg_decode_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 						 timestamptz_to_str(txn->prepare_time));
 
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
 /* COMMIT PREPARED callback */
@@ -599,7 +601,7 @@ tuple_to_stringinfo(StringInfo s, TupleDesc tupdesc, HeapTuple tuple, bool skip_
 /*
  * callback for individual changed tuples
  */
-static void
+static bool
 pg_decode_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 				 Relation relation, ReorderBufferChange *change)
 {
@@ -684,9 +686,10 @@ pg_decode_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	MemoryContextReset(data->context);
 
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
-static void
+static bool
 pg_decode_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 				   int nrelations, Relation relations[], ReorderBufferChange *change)
 {
@@ -739,6 +742,7 @@ pg_decode_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	MemoryContextReset(data->context);
 
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
 static void
@@ -818,7 +822,7 @@ pg_decode_stream_stop(LogicalDecodingContext *ctx,
 	OutputPluginWrite(ctx, true);
 }
 
-static void
+static bool
 pg_decode_stream_abort(LogicalDecodingContext *ctx,
 					   ReorderBufferTXN *txn,
 					   XLogRecPtr abort_lsn)
@@ -842,7 +846,7 @@ pg_decode_stream_abort(LogicalDecodingContext *ctx,
 	}
 
 	if (data->skip_empty_xacts && !xact_wrote_changes)
-		return;
+		return false;
 
 	OutputPluginPrepareWrite(ctx, true);
 	if (data->include_xids)
@@ -850,9 +854,10 @@ pg_decode_stream_abort(LogicalDecodingContext *ctx,
 	else
 		appendStringInfoString(ctx->out, "aborting streamed (sub)transaction");
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
-static void
+static bool
 pg_decode_stream_prepare(LogicalDecodingContext *ctx,
 						 ReorderBufferTXN *txn,
 						 XLogRecPtr prepare_lsn)
@@ -861,7 +866,7 @@ pg_decode_stream_prepare(LogicalDecodingContext *ctx,
 	TestDecodingTxnData *txndata = txn->output_plugin_private;
 
 	if (data->skip_empty_xacts && !txndata->xact_wrote_changes)
-		return;
+		return false;
 
 	OutputPluginPrepareWrite(ctx, true);
 
@@ -877,9 +882,10 @@ pg_decode_stream_prepare(LogicalDecodingContext *ctx,
 						 timestamptz_to_str(txn->prepare_time));
 
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
-static void
+static bool
 pg_decode_stream_commit(LogicalDecodingContext *ctx,
 						ReorderBufferTXN *txn,
 						XLogRecPtr commit_lsn)
@@ -892,7 +898,7 @@ pg_decode_stream_commit(LogicalDecodingContext *ctx,
 	txn->output_plugin_private = NULL;
 
 	if (data->skip_empty_xacts && !xact_wrote_changes)
-		return;
+		return false;
 
 	OutputPluginPrepareWrite(ctx, true);
 
@@ -906,6 +912,7 @@ pg_decode_stream_commit(LogicalDecodingContext *ctx,
 						 timestamptz_to_str(txn->commit_time));
 
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
 /*
@@ -913,7 +920,7 @@ pg_decode_stream_commit(LogicalDecodingContext *ctx,
  * at a later point in time.  We don't want users to see the changes until the
  * transaction is committed.
  */
-static void
+static bool
 pg_decode_stream_change(LogicalDecodingContext *ctx,
 						ReorderBufferTXN *txn,
 						Relation relation,
@@ -935,6 +942,7 @@ pg_decode_stream_change(LogicalDecodingContext *ctx,
 	else
 		appendStringInfoString(ctx->out, "streaming change for transaction");
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
 /*
@@ -981,7 +989,7 @@ pg_decode_stream_message(LogicalDecodingContext *ctx,
  * In streaming mode, we don't display the detailed information of Truncate.
  * See pg_decode_stream_change.
  */
-static void
+static bool
 pg_decode_stream_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 						  int nrelations, Relation relations[],
 						  ReorderBufferChange *change)
@@ -1001,4 +1009,5 @@ pg_decode_stream_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	else
 		appendStringInfoString(ctx->out, "streaming truncate for transaction");
 	OutputPluginWrite(ctx, true);
+	return true;
 }
diff --git a/doc/src/sgml/logicaldecoding.sgml b/doc/src/sgml/logicaldecoding.sgml
index d5a5e22fe2c..886c7d940df 100644
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -981,10 +981,15 @@ typedef void (*LogicalDecodeBeginCB) (struct LogicalDecodingContext *ctx,
       rows will have been called before this, if there have been any modified
       rows.
 <programlisting>
-typedef void (*LogicalDecodeCommitCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeCommitCB) (struct LogicalDecodingContext *ctx,
                                        ReorderBufferTXN *txn,
                                        XLogRecPtr commit_lsn);
 </programlisting>
+      If the callback outputs the transaction, it is expected to return true;
+      otherwise false. The return value is used to update the
+      <literal>sent_txns</literal> counter reported in <link
+      linkend="monitoring-pg-stat-replication-slots-view">
+      <structname>pg_stat_replication_slots</structname></link> view.
      </para>
     </sect3>
 
@@ -1005,7 +1010,7 @@ typedef void (*LogicalDecodeCommitCB) (struct LogicalDecodingContext *ctx,
       this very same transaction. In that case, the logical decoding of this
       aborted transaction is stopped gracefully.
 <programlisting>
-typedef void (*LogicalDecodeChangeCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeChangeCB) (struct LogicalDecodingContext *ctx,
                                        ReorderBufferTXN *txn,
                                        Relation relation,
                                        ReorderBufferChange *change);
@@ -1015,8 +1020,12 @@ typedef void (*LogicalDecodeChangeCB) (struct LogicalDecodingContext *ctx,
       and <function>commit_cb</function> callbacks, but additionally the
       relation descriptor <parameter>relation</parameter> points to the
       relation the row belongs to and a struct
-      <parameter>change</parameter> describing the row modification are passed
-      in.
+      <parameter>change</parameter> describing the row modification are passed in.
+      If the output plugin decoded and output the change, it is expected
+      to return true; otherwise false. This return value is used to update the
+      <structfield>filtered_bytes</structfield> counter reported in
+      <link linkend="monitoring-pg-stat-replication-slots-view">
+      <structname>pg_stat_replication_slots</structname></link> view.
      </para>
 
      <note>
@@ -1036,18 +1045,18 @@ typedef void (*LogicalDecodeChangeCB) (struct LogicalDecodingContext *ctx,
       The optional <function>truncate_cb</function> callback is called for a
       <command>TRUNCATE</command> command.
 <programlisting>
-typedef void (*LogicalDecodeTruncateCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeTruncateCB) (struct LogicalDecodingContext *ctx,
                                          ReorderBufferTXN *txn,
                                          int nrelations,
                                          Relation relations[],
                                          ReorderBufferChange *change);
 </programlisting>
-      The parameters are analogous to the <function>change_cb</function>
-      callback.  However, because <command>TRUNCATE</command> actions on
-      tables connected by foreign keys need to be executed together, this
-      callback receives an array of relations instead of just a single one.
-      See the description of the <xref linkend="sql-truncate"/> statement for
-      details.
+      The parameters and the expected return value are analogous to the
+      <function>change_cb</function> callback.  However, because
+      <command>TRUNCATE</command> actions on tables connected by foreign keys
+      need to be executed together, this callback receives an array of relations
+      instead of just a single one.  See the description of the <xref
+      linkend="sql-truncate"/> statement for details.
      </para>
     </sect3>
 
@@ -1180,8 +1189,18 @@ typedef void (*LogicalDecodeBeginPrepareCB) (struct LogicalDecodingContext *ctx,
       rows will have been called before this, if there have been any modified
       rows. The <parameter>gid</parameter> field, which is part of the
       <parameter>txn</parameter> parameter, can be used in this callback.
+      If the callback outputs the prepared transaction, it is expected to return
+      true; otherwise false. The return value is used to update the
+      <structfield>sent_txns</structfield> counter reported in
+      <link linkend="monitoring-pg-stat-replication-slots-view">
+      <structname>pg_stat_replication_slots</structname></link> view. Please
+      note that the return value of this callback suffices to determine
+      whether a prepared transaction was output or not; callbacks
+      <function>commit_prepared_cb</function> and
+      <function>rollback_prepared_cb</function> do not need to return this
+      status again.
 <programlisting>
-typedef void (*LogicalDecodePrepareCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodePrepareCB) (struct LogicalDecodingContext *ctx,
                                         ReorderBufferTXN *txn,
                                         XLogRecPtr prepare_lsn);
 </programlisting>
@@ -1255,9 +1274,14 @@ typedef void (*LogicalDecodeStreamStopCB) (struct LogicalDecodingContext *ctx,
      <title>Stream Abort Callback</title>
      <para>
       The required <function>stream_abort_cb</function> callback is called to
-      abort a previously streamed transaction.
+      abort a previously streamed transaction. If the output plugin has output
+      the streamed transaction, the callback is expected to return true;
+      otherwise false. The return value is used to update the
+      <structfield>sent_txns</structfield> counter reported in
+      <link linkend="monitoring-pg-stat-replication-slots-view">
+      <structname>pg_stat_replication_slots</structname></link> view.
 <programlisting>
-typedef void (*LogicalDecodeStreamAbortCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamAbortCB) (struct LogicalDecodingContext *ctx,
                                             ReorderBufferTXN *txn,
                                             XLogRecPtr abort_lsn);
 </programlisting>
@@ -1270,9 +1294,19 @@ typedef void (*LogicalDecodeStreamAbortCB) (struct LogicalDecodingContext *ctx,
       The <function>stream_prepare_cb</function> callback is called to prepare
       a previously streamed transaction as part of a two-phase commit. This
       callback is required when the output plugin supports both the streaming
-      of large in-progress transactions and two-phase commits.
+      of large in-progress transactions and two-phase commits. If the output
+      plugin has output the streamed transaction, the callback is expected to
+      return true; otherwise false. The return value is used to update the
+      <structfield>sent_txns</structfield> counter reported in
+      <link linkend="monitoring-pg-stat-replication-slots-view">
+      <structname>pg_stat_replication_slots</structname></link> view. Please
+      note that only the return value of this callback suffices to determine
+      whether a prepared transaction was output or not; callbacks
+      <function>commit_prepared_cb</function> and
+      <function>rollback_prepared_cb</function> do not need to return this
+      status again.
       <programlisting>
-typedef void (*LogicalDecodeStreamPrepareCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamPrepareCB) (struct LogicalDecodingContext *ctx,
                                               ReorderBufferTXN *txn,
                                               XLogRecPtr prepare_lsn);
 </programlisting>
@@ -1283,9 +1317,14 @@ typedef void (*LogicalDecodeStreamPrepareCB) (struct LogicalDecodingContext *ctx
      <title>Stream Commit Callback</title>
      <para>
       The required <function>stream_commit_cb</function> callback is called to
-      commit a previously streamed transaction.
+      commit a previously streamed transaction. If the output plugin
+      has output the streamed transaction, the callback is expected to return
+      true; otherwise false. The return value is used to update the
+      <structfield>sent_txns</structfield> counter reported in
+      <link linkend="monitoring-pg-stat-replication-slots-view">
+      <structname>pg_stat_replication_slots</structname></link> view.
 <programlisting>
-typedef void (*LogicalDecodeStreamCommitCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamCommitCB) (struct LogicalDecodingContext *ctx,
                                              ReorderBufferTXN *txn,
                                              XLogRecPtr commit_lsn);
 </programlisting>
@@ -1298,10 +1337,15 @@ typedef void (*LogicalDecodeStreamCommitCB) (struct LogicalDecodingContext *ctx,
       The required <function>stream_change_cb</function> callback is called
       when sending a change in a block of streamed changes (demarcated by
       <function>stream_start_cb</function> and <function>stream_stop_cb</function> calls).
+      If the output plugin decoded and output the change, it is expected to
+      return true. Otherwise it is expected to return false. This return value
+      is used to update the <structfield>filtered_bytes</structfield> counter
+      reported in <link linkend="monitoring-pg-stat-replication-slots-view">
+      <structname>pg_stat_replication_slots</structname></link> view.
       The actual changes are not displayed as the transaction can abort at a later
       point in time and we don't decode changes for aborted transactions.
 <programlisting>
-typedef void (*LogicalDecodeStreamChangeCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamChangeCB) (struct LogicalDecodingContext *ctx,
                                              ReorderBufferTXN *txn,
                                              Relation relation,
                                              ReorderBufferChange *change);
@@ -1338,18 +1382,18 @@ typedef void (*LogicalDecodeStreamMessageCB) (struct LogicalDecodingContext *ctx
       (demarcated by <function>stream_start_cb</function> and
       <function>stream_stop_cb</function> calls).
 <programlisting>
-typedef void (*LogicalDecodeStreamTruncateCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamTruncateCB) (struct LogicalDecodingContext *ctx,
                                                ReorderBufferTXN *txn,
                                                int nrelations,
                                                Relation relations[],
                                                ReorderBufferChange *change);
 </programlisting>
-      The parameters are analogous to the <function>stream_change_cb</function>
-      callback.  However, because <command>TRUNCATE</command> actions on
-      tables connected by foreign keys need to be executed together, this
-      callback receives an array of relations instead of just a single one.
-      See the description of the <xref linkend="sql-truncate"/> statement for
-      details.
+      The parameters and the return value are analogous to the
+      <function>stream_change_cb</function> callback.  However, because
+      <command>TRUNCATE</command> actions on tables connected by foreign keys
+      need to be executed together, this callback receives an array of relations
+      instead of just a single one.  See the description of the <xref
+      linkend="sql-truncate"/> statement for details.
      </para>
     </sect3>
 
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 817fd9f4ca7..d3710e762e4 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -1547,6 +1547,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </para></entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>plugin</structfield> <type>text</type>
+       </para>
+       <para>
+        The base name of the shared object containing the output plugin this
+        logical slot is using. This column is same as the one in
+        <structname>pg_replication_slots</structname>.
+      </para></entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>spill_txns</structfield> <type>bigint</type>
@@ -1635,19 +1646,19 @@ description | Waiting for a newly initialized WAL file to reach durable storage
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_txns</structfield> <type>bigint</type>
+        <structfield>total_wal_txns</structfield> <type>bigint</type>
        </para>
        <para>
-        Number of decoded transactions sent to the decoding output plugin for
-        this slot. This counts top-level transactions only, and is not incremented
-        for subtransactions. Note that this includes the transactions that are
-        streamed and/or spilled.
+        Number of decoded transactions from WAL sent to the decoding output
+        plugin for this slot. This counts top-level transactions only, and is
+        not incremented for subtransactions. Note that this includes the
+        transactions that are streamed and/or spilled.
        </para></entry>
      </row>
 
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-        <structfield>total_bytes</structfield><type>bigint</type>
+        <structfield>total_wal_bytes</structfield><type>bigint</type>
        </para>
        <para>
         Amount of transaction data decoded for sending transactions to the
@@ -1657,6 +1668,42 @@ description | Waiting for a newly initialized WAL file to reach durable storage
       </entry>
      </row>
 
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>filtered_bytes</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Amount of changes, from <structfield>total_wal_bytes</structfield>, filtered
+        out by the output plugin and not sent downstream. Please note that it
+        does not include the changes filtered before a change is sent to
+        the output plugin, e.g. the changes filtered by origin.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>sent_txns</structfield> <type>bigint</type>
+       </para>
+       <para>
+        Number of decoded transactions sent downstream for this slot. This
+        counts top-level transactions only, and is not incremented for
+        subtransactions. These transactions are subset of transactions sent to
+        the decoding plugin. Hence this count is expected to be less than or
+        equal to <structfield>total_wal_txns</structfield>.
+       </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+        <structfield>sent_bytes</structfield><type>bigint</type>
+       </para>
+       <para>
+        Amount of transaction changes, in the output format, sent downstream for
+        this slot by the output plugin.
+       </para>
+      </entry>
+     </row>
+
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
         <structfield>slotsync_skip_count</structfield><type>bigint</type>
@@ -1693,6 +1740,17 @@ description | Waiting for a newly initialized WAL file to reach durable storage
    </tgroup>
   </table>
 
+  <note>
+   <para>
+    The accuracy of columns <structfield>filtered_bytes</structfield>, and
+    <structfield>sent_txns</structfield> depends upon the accuracy of return values
+    from respective callbacks associated with those counts as mentioned in <xref
+    linkend="logicaldecoding-output-plugin-callbacks"/>. A descripancy in those
+    counts may be result of incorrect implementation of those callbacks in the
+    output plugin given by column <structfield>plugin</structfield>.
+   </para>
+  </note>
+
  </sect2>
 
  <sect2 id="monitoring-pg-stat-wal-receiver-view">
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 0a0f95f6bb9..2b30361d32a 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1068,6 +1068,7 @@ CREATE VIEW pg_replication_slots AS
 CREATE VIEW pg_stat_replication_slots AS
     SELECT
             s.slot_name,
+            r.plugin,
             s.spill_txns,
             s.spill_count,
             s.spill_bytes,
@@ -1075,8 +1076,11 @@ CREATE VIEW pg_stat_replication_slots AS
             s.stream_count,
             s.stream_bytes,
             s.mem_exceeded_count,
-            s.total_txns,
-            s.total_bytes,
+            s.total_wal_txns,
+            s.total_wal_bytes,
+            s.filtered_bytes,
+            s.sent_txns,
+            s.sent_bytes,
             s.slotsync_skip_count,
             s.slotsync_last_skip,
             s.stats_reset
diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 1b11ed63dc6..c65399a9c3d 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -888,7 +888,8 @@ commit_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
 	ctx->end_xact = true;
 
 	/* do the actual work: call callback */
-	ctx->callbacks.commit_cb(ctx, txn, commit_lsn);
+	if (ctx->callbacks.commit_cb(ctx, txn, commit_lsn))
+		cache->sentTxns++;
 
 	/* Pop the error context stack */
 	error_context_stack = errcallback.previous;
@@ -984,7 +985,8 @@ prepare_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
 						"prepare_cb")));
 
 	/* do the actual work: call callback */
-	ctx->callbacks.prepare_cb(ctx, txn, prepare_lsn);
+	if (ctx->callbacks.prepare_cb(ctx, txn, prepare_lsn))
+		cache->sentTxns++;
 
 	/* Pop the error context stack */
 	error_context_stack = errcallback.previous;
@@ -1115,7 +1117,8 @@ change_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
 
 	ctx->end_xact = false;
 
-	ctx->callbacks.change_cb(ctx, txn, relation, change);
+	if (!ctx->callbacks.change_cb(ctx, txn, relation, change))
+		cache->filteredBytes += ReorderBufferChangeSize(change);
 
 	/* Pop the error context stack */
 	error_context_stack = errcallback.previous;
@@ -1157,7 +1160,8 @@ truncate_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
 
 	ctx->end_xact = false;
 
-	ctx->callbacks.truncate_cb(ctx, txn, nrelations, relations, change);
+	if (!ctx->callbacks.truncate_cb(ctx, txn, nrelations, relations, change))
+		cache->filteredBytes += ReorderBufferChangeSize(change);
 
 	/* Pop the error context stack */
 	error_context_stack = errcallback.previous;
@@ -1396,7 +1400,8 @@ stream_abort_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
 				 errmsg("logical streaming requires a %s callback",
 						"stream_abort_cb")));
 
-	ctx->callbacks.stream_abort_cb(ctx, txn, abort_lsn);
+	if (ctx->callbacks.stream_abort_cb(ctx, txn, abort_lsn))
+		cache->sentTxns++;
 
 	/* Pop the error context stack */
 	error_context_stack = errcallback.previous;
@@ -1441,7 +1446,8 @@ stream_prepare_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
 				 errmsg("logical streaming at prepare time requires a %s callback",
 						"stream_prepare_cb")));
 
-	ctx->callbacks.stream_prepare_cb(ctx, txn, prepare_lsn);
+	if (ctx->callbacks.stream_prepare_cb(ctx, txn, prepare_lsn))
+		cache->sentTxns++;
 
 	/* Pop the error context stack */
 	error_context_stack = errcallback.previous;
@@ -1482,7 +1488,8 @@ stream_commit_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
 				 errmsg("logical streaming requires a %s callback",
 						"stream_commit_cb")));
 
-	ctx->callbacks.stream_commit_cb(ctx, txn, commit_lsn);
+	if (ctx->callbacks.stream_commit_cb(ctx, txn, commit_lsn))
+		cache->sentTxns++;
 
 	/* Pop the error context stack */
 	error_context_stack = errcallback.previous;
@@ -1531,7 +1538,8 @@ stream_change_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
 				 errmsg("logical streaming requires a %s callback",
 						"stream_change_cb")));
 
-	ctx->callbacks.stream_change_cb(ctx, txn, relation, change);
+	if (!ctx->callbacks.stream_change_cb(ctx, txn, relation, change))
+		cache->filteredBytes += ReorderBufferChangeSize(change);
 
 	/* Pop the error context stack */
 	error_context_stack = errcallback.previous;
@@ -1619,7 +1627,8 @@ stream_truncate_cb_wrapper(ReorderBuffer *cache, ReorderBufferTXN *txn,
 
 	ctx->end_xact = false;
 
-	ctx->callbacks.stream_truncate_cb(ctx, txn, nrelations, relations, change);
+	if (!ctx->callbacks.stream_truncate_cb(ctx, txn, nrelations, relations, change))
+		cache->filteredBytes += ReorderBufferChangeSize(change);
 
 	/* Pop the error context stack */
 	error_context_stack = errcallback.previous;
@@ -1959,7 +1968,7 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		rb->memExceededCount <= 0)
 		return;
 
-	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
+	elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
 		 rb,
 		 rb->spillTxns,
 		 rb->spillCount,
@@ -1969,7 +1978,10 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 		 rb->streamBytes,
 		 rb->memExceededCount,
 		 rb->totalTxns,
-		 rb->totalBytes);
+		 rb->totalBytes,
+		 rb->sentTxns,
+		 rb->sentBytes,
+		 rb->filteredBytes);
 
 	repSlotStat.spill_txns = rb->spillTxns;
 	repSlotStat.spill_count = rb->spillCount;
@@ -1978,8 +1990,11 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	repSlotStat.stream_count = rb->streamCount;
 	repSlotStat.stream_bytes = rb->streamBytes;
 	repSlotStat.mem_exceeded_count = rb->memExceededCount;
-	repSlotStat.total_txns = rb->totalTxns;
-	repSlotStat.total_bytes = rb->totalBytes;
+	repSlotStat.total_wal_txns = rb->totalTxns;
+	repSlotStat.total_wal_bytes = rb->totalBytes;
+	repSlotStat.sent_txns = rb->sentTxns;
+	repSlotStat.sent_bytes = rb->sentBytes;
+	repSlotStat.filtered_bytes = rb->filteredBytes;
 
 	pgstat_report_replslot(ctx->slot, &repSlotStat);
 
@@ -1992,6 +2007,9 @@ UpdateDecodingStats(LogicalDecodingContext *ctx)
 	rb->memExceededCount = 0;
 	rb->totalTxns = 0;
 	rb->totalBytes = 0;
+	rb->sentTxns = 0;
+	rb->sentBytes = 0;
+	rb->filteredBytes = 0;
 }
 
 /*
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index cf77ee28dfe..0acbda94941 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -65,6 +65,7 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 	Datum		values[3];
 	bool		nulls[3];
 	DecodingOutputState *p;
+	int64		sentBytes = 0;
 
 	/* SQL Datums can only be of a limited length... */
 	if (ctx->out->len > MaxAllocSize - VARHDRSZ)
@@ -74,7 +75,9 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 
 	memset(nulls, 0, sizeof(nulls));
 	values[0] = LSNGetDatum(lsn);
+	sentBytes += sizeof(XLogRecPtr);
 	values[1] = TransactionIdGetDatum(xid);
+	sentBytes += sizeof(TransactionId);
 
 	/*
 	 * Assert ctx->out is in database encoding when we're writing textual
@@ -87,8 +90,13 @@ LogicalOutputWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xi
 
 	/* ick, but cstring_to_text_with_len works for bytea perfectly fine */
 	values[2] = PointerGetDatum(cstring_to_text_with_len(ctx->out->data, ctx->out->len));
+	sentBytes += ctx->out->len;
 
 	tuplestore_putvalues(p->tupstore, p->tupdesc, values, nulls);
+
+	/* Update the amount of data sent downstream. */
+	ctx->reorder->sentBytes += sentBytes;
+
 	p->returned_rows++;
 }
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index f18c6fb52b5..e4e65688235 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -310,7 +310,6 @@ static void ReorderBufferToastAppendChunk(ReorderBuffer *rb, ReorderBufferTXN *t
  * memory accounting
  * ---------------------------------------
  */
-static Size ReorderBufferChangeSize(ReorderBufferChange *change);
 static void ReorderBufferChangeMemoryUpdate(ReorderBuffer *rb,
 											ReorderBufferChange *change,
 											ReorderBufferTXN *txn,
@@ -393,6 +392,9 @@ ReorderBufferAllocate(void)
 	buffer->memExceededCount = 0;
 	buffer->totalTxns = 0;
 	buffer->totalBytes = 0;
+	buffer->sentTxns = 0;
+	buffer->sentBytes = 0;
+	buffer->filteredBytes = 0;
 
 	buffer->current_restart_decoding_lsn = InvalidXLogRecPtr;
 
@@ -4455,7 +4457,7 @@ ReorderBufferStreamTXN(ReorderBuffer *rb, ReorderBufferTXN *txn)
 /*
  * Size of a change in memory.
  */
-static Size
+Size
 ReorderBufferChangeSize(ReorderBufferChange *change)
 {
 	Size		sz = sizeof(ReorderBufferChange);
diff --git a/src/backend/replication/pgoutput/pgoutput.c b/src/backend/replication/pgoutput/pgoutput.c
index 787998abb8a..8377c2ea464 100644
--- a/src/backend/replication/pgoutput/pgoutput.c
+++ b/src/backend/replication/pgoutput/pgoutput.c
@@ -46,12 +46,12 @@ static void pgoutput_startup(LogicalDecodingContext *ctx,
 static void pgoutput_shutdown(LogicalDecodingContext *ctx);
 static void pgoutput_begin_txn(LogicalDecodingContext *ctx,
 							   ReorderBufferTXN *txn);
-static void pgoutput_commit_txn(LogicalDecodingContext *ctx,
+static bool pgoutput_commit_txn(LogicalDecodingContext *ctx,
 								ReorderBufferTXN *txn, XLogRecPtr commit_lsn);
-static void pgoutput_change(LogicalDecodingContext *ctx,
+static bool pgoutput_change(LogicalDecodingContext *ctx,
 							ReorderBufferTXN *txn, Relation relation,
 							ReorderBufferChange *change);
-static void pgoutput_truncate(LogicalDecodingContext *ctx,
+static bool pgoutput_truncate(LogicalDecodingContext *ctx,
 							  ReorderBufferTXN *txn, int nrelations, Relation relations[],
 							  ReorderBufferChange *change);
 static void pgoutput_message(LogicalDecodingContext *ctx,
@@ -62,7 +62,7 @@ static bool pgoutput_origin_filter(LogicalDecodingContext *ctx,
 								   RepOriginId origin_id);
 static void pgoutput_begin_prepare_txn(LogicalDecodingContext *ctx,
 									   ReorderBufferTXN *txn);
-static void pgoutput_prepare_txn(LogicalDecodingContext *ctx,
+static bool pgoutput_prepare_txn(LogicalDecodingContext *ctx,
 								 ReorderBufferTXN *txn, XLogRecPtr prepare_lsn);
 static void pgoutput_commit_prepared_txn(LogicalDecodingContext *ctx,
 										 ReorderBufferTXN *txn, XLogRecPtr commit_lsn);
@@ -74,13 +74,13 @@ static void pgoutput_stream_start(struct LogicalDecodingContext *ctx,
 								  ReorderBufferTXN *txn);
 static void pgoutput_stream_stop(struct LogicalDecodingContext *ctx,
 								 ReorderBufferTXN *txn);
-static void pgoutput_stream_abort(struct LogicalDecodingContext *ctx,
+static bool pgoutput_stream_abort(struct LogicalDecodingContext *ctx,
 								  ReorderBufferTXN *txn,
 								  XLogRecPtr abort_lsn);
-static void pgoutput_stream_commit(struct LogicalDecodingContext *ctx,
+static bool pgoutput_stream_commit(struct LogicalDecodingContext *ctx,
 								   ReorderBufferTXN *txn,
 								   XLogRecPtr commit_lsn);
-static void pgoutput_stream_prepare_txn(LogicalDecodingContext *ctx,
+static bool pgoutput_stream_prepare_txn(LogicalDecodingContext *ctx,
 										ReorderBufferTXN *txn, XLogRecPtr prepare_lsn);
 
 static bool publications_valid;
@@ -624,7 +624,7 @@ pgoutput_send_begin(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 /*
  * COMMIT callback
  */
-static void
+static bool
 pgoutput_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 					XLogRecPtr commit_lsn)
 {
@@ -645,12 +645,13 @@ pgoutput_commit_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	if (!sent_begin_txn)
 	{
 		elog(DEBUG1, "skipped replication of an empty transaction with XID: %u", txn->xid);
-		return;
+		return false;
 	}
 
 	OutputPluginPrepareWrite(ctx, true);
 	logicalrep_write_commit(ctx->out, txn, commit_lsn);
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
 /*
@@ -673,7 +674,7 @@ pgoutput_begin_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn)
 /*
  * PREPARE callback
  */
-static void
+static bool
 pgoutput_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 					 XLogRecPtr prepare_lsn)
 {
@@ -682,6 +683,7 @@ pgoutput_prepare_txn(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	OutputPluginPrepareWrite(ctx, true);
 	logicalrep_write_prepare(ctx->out, txn, prepare_lsn);
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
 /*
@@ -1476,7 +1478,7 @@ pgoutput_row_filter(Relation relation, TupleTableSlot *old_slot,
  *
  * This is called both in streaming and non-streaming modes.
  */
-static void
+static bool
 pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 				Relation relation, ReorderBufferChange *change)
 {
@@ -1490,9 +1492,10 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	ReorderBufferChangeType action = change->action;
 	TupleTableSlot *old_slot = NULL;
 	TupleTableSlot *new_slot = NULL;
+	bool		result;
 
 	if (!is_publishable_relation(relation))
-		return;
+		return false;
 
 	/*
 	 * Remember the xid for the change in streaming mode. We need to send xid
@@ -1510,15 +1513,15 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	{
 		case REORDER_BUFFER_CHANGE_INSERT:
 			if (!relentry->pubactions.pubinsert)
-				return;
+				return false;
 			break;
 		case REORDER_BUFFER_CHANGE_UPDATE:
 			if (!relentry->pubactions.pubupdate)
-				return;
+				return false;
 			break;
 		case REORDER_BUFFER_CHANGE_DELETE:
 			if (!relentry->pubactions.pubdelete)
-				return;
+				return false;
 
 			/*
 			 * This is only possible if deletes are allowed even when replica
@@ -1528,7 +1531,7 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 			if (!change->data.tp.oldtuple)
 			{
 				elog(DEBUG1, "didn't send DELETE change because of missing oldtuple");
-				return;
+				return false;
 			}
 			break;
 		default:
@@ -1583,7 +1586,16 @@ pgoutput_change(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	 * of the row filter for old and new tuple.
 	 */
 	if (!pgoutput_row_filter(targetrel, old_slot, &new_slot, relentry, &action))
+	{
+		result = false;
 		goto cleanup;
+	}
+
+	/*
+	 * Even if we filter some columns while sending the message we are not
+	 * filtering the change as a whole. Hence we will return true.
+	 */
+	result = true;
 
 	/*
 	 * Send BEGIN if we haven't yet.
@@ -1646,9 +1658,10 @@ cleanup:
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
+	return result;
 }
 
-static void
+static bool
 pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 				  int nrelations, Relation relations[], ReorderBufferChange *change)
 {
@@ -1660,6 +1673,7 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 	int			nrelids;
 	Oid		   *relids;
 	TransactionId xid = InvalidTransactionId;
+	bool		result = false;
 
 	/* Remember the xid for the change in streaming mode. See pgoutput_change. */
 	if (data->in_streaming)
@@ -1710,10 +1724,18 @@ pgoutput_truncate(LogicalDecodingContext *ctx, ReorderBufferTXN *txn,
 								  change->data.truncate.cascade,
 								  change->data.truncate.restart_seqs);
 		OutputPluginWrite(ctx, true);
+
+		/*
+		 * Even if we filtered out some relations, we still send a TRUNCATE
+		 * message for the remaining relations. Since the change, as a whole,
+		 * is not filtered out we return true.
+		 */
+		result = true;
 	}
 
 	MemoryContextSwitchTo(old);
 	MemoryContextReset(data->context);
+	return result;
 }
 
 static void
@@ -1885,7 +1907,7 @@ pgoutput_stream_stop(struct LogicalDecodingContext *ctx,
  * Notify downstream to discard the streamed transaction (along with all
  * its subtransactions, if it's a toplevel transaction).
  */
-static void
+static bool
 pgoutput_stream_abort(struct LogicalDecodingContext *ctx,
 					  ReorderBufferTXN *txn,
 					  XLogRecPtr abort_lsn)
@@ -1912,13 +1934,14 @@ pgoutput_stream_abort(struct LogicalDecodingContext *ctx,
 	OutputPluginWrite(ctx, true);
 
 	cleanup_rel_sync_cache(toptxn->xid, false);
+	return true;
 }
 
 /*
  * Notify downstream to apply the streamed transaction (along with all
  * its subtransactions).
  */
-static void
+static bool
 pgoutput_stream_commit(struct LogicalDecodingContext *ctx,
 					   ReorderBufferTXN *txn,
 					   XLogRecPtr commit_lsn)
@@ -1939,6 +1962,7 @@ pgoutput_stream_commit(struct LogicalDecodingContext *ctx,
 	OutputPluginWrite(ctx, true);
 
 	cleanup_rel_sync_cache(txn->xid, true);
+	return true;
 }
 
 /*
@@ -1946,7 +1970,7 @@ pgoutput_stream_commit(struct LogicalDecodingContext *ctx,
  *
  * Notify the downstream to prepare the transaction.
  */
-static void
+static bool
 pgoutput_stream_prepare_txn(LogicalDecodingContext *ctx,
 							ReorderBufferTXN *txn,
 							XLogRecPtr prepare_lsn)
@@ -1957,6 +1981,7 @@ pgoutput_stream_prepare_txn(LogicalDecodingContext *ctx,
 	OutputPluginPrepareWrite(ctx, true);
 	logicalrep_write_stream_prepare(ctx->out, txn, prepare_lsn);
 	OutputPluginWrite(ctx, true);
+	return true;
 }
 
 /*
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 449632ad1aa..8ff11f7e5c8 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1587,6 +1587,9 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
 	/* output previously gathered data in a CopyData packet */
 	pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
 
+	/* Update the amount of data sent downstream. */
+	ctx->reorder->sentBytes += ctx->out->len + 1;	/* +1 for the 'd' */
+
 	CHECK_FOR_INTERRUPTS();
 
 	/* Try to flush pending output to the client */
diff --git a/src/backend/utils/activity/pgstat_replslot.c b/src/backend/utils/activity/pgstat_replslot.c
index d757e00eb54..541c39bd0cc 100644
--- a/src/backend/utils/activity/pgstat_replslot.c
+++ b/src/backend/utils/activity/pgstat_replslot.c
@@ -95,8 +95,11 @@ pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *re
 	REPLSLOT_ACC(stream_count);
 	REPLSLOT_ACC(stream_bytes);
 	REPLSLOT_ACC(mem_exceeded_count);
-	REPLSLOT_ACC(total_txns);
-	REPLSLOT_ACC(total_bytes);
+	REPLSLOT_ACC(total_wal_txns);
+	REPLSLOT_ACC(total_wal_bytes);
+	REPLSLOT_ACC(sent_txns);
+	REPLSLOT_ACC(sent_bytes);
+	REPLSLOT_ACC(filtered_bytes);
 #undef REPLSLOT_ACC
 
 	pgstat_unlock_entry(entry_ref);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index ef6fffe60b9..3752a89553c 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2129,7 +2129,7 @@ pg_stat_get_archiver(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_REPLICATION_SLOT_COLS 13
+#define PG_STAT_GET_REPLICATION_SLOT_COLS 16
 	text	   *slotname_text = PG_GETARG_TEXT_P(0);
 	NameData	slotname;
 	TupleDesc	tupdesc;
@@ -2156,15 +2156,21 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 					   INT8OID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "mem_exceeded_count",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_txns",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "total_wal_txns",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "total_bytes",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "total_wal_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "slotsync_skip_count",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "filtered_bytes",
 					   INT8OID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "slotsync_last_skip",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "sent_txns",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "sent_bytes",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 14, "slotsync_skip_count",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 15, "slotsync_last_skip",
 					   TIMESTAMPTZOID, -1, 0);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "stats_reset",
+	TupleDescInitEntry(tupdesc, (AttrNumber) 16, "stats_reset",
 					   TIMESTAMPTZOID, -1, 0);
 	BlessTupleDesc(tupdesc);
 
@@ -2188,19 +2194,22 @@ pg_stat_get_replication_slot(PG_FUNCTION_ARGS)
 	values[5] = Int64GetDatum(slotent->stream_count);
 	values[6] = Int64GetDatum(slotent->stream_bytes);
 	values[7] = Int64GetDatum(slotent->mem_exceeded_count);
-	values[8] = Int64GetDatum(slotent->total_txns);
-	values[9] = Int64GetDatum(slotent->total_bytes);
-	values[10] = Int64GetDatum(slotent->slotsync_skip_count);
+	values[8] = Int64GetDatum(slotent->total_wal_txns);
+	values[9] = Int64GetDatum(slotent->total_wal_bytes);
+	values[10] = Int64GetDatum(slotent->filtered_bytes);
+	values[11] = Int64GetDatum(slotent->sent_txns);
+	values[12] = Int64GetDatum(slotent->sent_bytes);
+	values[13] = Int64GetDatum(slotent->slotsync_skip_count);
 
 	if (slotent->slotsync_last_skip == 0)
-		nulls[11] = true;
+		nulls[14] = true;
 	else
-		values[11] = TimestampTzGetDatum(slotent->slotsync_last_skip);
+		values[14] = TimestampTzGetDatum(slotent->slotsync_last_skip);
 
 	if (slotent->stat_reset_timestamp == 0)
-		nulls[12] = true;
+		nulls[15] = true;
 	else
-		values[12] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
+		values[15] = TimestampTzGetDatum(slotent->stat_reset_timestamp);
 
 	/* Returns the record as Datum */
 	PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index fd9448ec7b9..8cd14c88bdb 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5691,9 +5691,9 @@
 { oid => '6169', descr => 'statistics: information about replication slot',
   proname => 'pg_stat_get_replication_slot', provolatile => 's',
   proparallel => 'r', prorettype => 'record', proargtypes => 'text',
-  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz,timestamptz}',
-  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o}',
-  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,mem_exceeded_count,total_txns,total_bytes,slotsync_skip_count,slotsync_last_skip,stats_reset}',
+  proallargtypes => '{text,text,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,int8,timestamptz,timestamptz}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{slot_name,slot_name,spill_txns,spill_count,spill_bytes,stream_txns,stream_count,stream_bytes,mem_exceeded_count,total_wal_txns,total_wal_bytes,filtered_bytes,sent_txns,sent_bytes,slotsync_skip_count,slotsync_last_skip,stats_reset}',
   prosrc => 'pg_stat_get_replication_slot' },
 
 { oid => '6230', descr => 'statistics: check if a stats object exists',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index f23dd5870da..cc4e0a561b0 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -398,8 +398,11 @@ typedef struct PgStat_StatReplSlotEntry
 	PgStat_Counter stream_count;
 	PgStat_Counter stream_bytes;
 	PgStat_Counter mem_exceeded_count;
-	PgStat_Counter total_txns;
-	PgStat_Counter total_bytes;
+	PgStat_Counter total_wal_txns;
+	PgStat_Counter total_wal_bytes;
+	PgStat_Counter sent_txns;
+	PgStat_Counter sent_bytes;
+	PgStat_Counter filtered_bytes;
 	PgStat_Counter slotsync_skip_count;
 	TimestampTz slotsync_last_skip;
 	TimestampTz stat_reset_timestamp;
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
index 8d4d5b71887..8c27e8266e7 100644
--- a/src/include/replication/output_plugin.h
+++ b/src/include/replication/output_plugin.h
@@ -56,17 +56,19 @@ typedef void (*LogicalDecodeBeginCB) (struct LogicalDecodingContext *ctx,
 									  ReorderBufferTXN *txn);
 
 /*
- * Callback for every individual change in a successful transaction.
+ * Callback for every individual change in a successful transaction. Should
+ * return true if the change is output, false otherwise.
  */
-typedef void (*LogicalDecodeChangeCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeChangeCB) (struct LogicalDecodingContext *ctx,
 									   ReorderBufferTXN *txn,
 									   Relation relation,
 									   ReorderBufferChange *change);
 
 /*
- * Callback for every TRUNCATE in a successful transaction.
+ * Callback for every TRUNCATE in a successful transaction. Should return true if
+ * the change is output, false otherwise.
  */
-typedef void (*LogicalDecodeTruncateCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeTruncateCB) (struct LogicalDecodingContext *ctx,
 										 ReorderBufferTXN *txn,
 										 int nrelations,
 										 Relation relations[],
@@ -74,8 +76,9 @@ typedef void (*LogicalDecodeTruncateCB) (struct LogicalDecodingContext *ctx,
 
 /*
  * Called for every (explicit or implicit) COMMIT of a successful transaction.
+ * Should return true if the transaction is output, false otherwise.
  */
-typedef void (*LogicalDecodeCommitCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeCommitCB) (struct LogicalDecodingContext *ctx,
 									   ReorderBufferTXN *txn,
 									   XLogRecPtr commit_lsn);
 
@@ -118,10 +121,10 @@ typedef void (*LogicalDecodeBeginPrepareCB) (struct LogicalDecodingContext *ctx,
 											 ReorderBufferTXN *txn);
 
 /*
- * Called for PREPARE record unless it was filtered by filter_prepare()
- * callback.
+ * Called for PREPARE record unless it was filtered by filter_prepare() callback.
+ * Should return true if the transaction is output, false otherwise.
  */
-typedef void (*LogicalDecodePrepareCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodePrepareCB) (struct LogicalDecodingContext *ctx,
 										ReorderBufferTXN *txn,
 										XLogRecPtr prepare_lsn);
 
@@ -159,32 +162,35 @@ typedef void (*LogicalDecodeStreamStopCB) (struct LogicalDecodingContext *ctx,
 
 /*
  * Called to discard changes streamed to remote node from in-progress
- * transaction.
+ * transaction. Should return true if the transaction is output, false
+ * otherwise.
  */
-typedef void (*LogicalDecodeStreamAbortCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamAbortCB) (struct LogicalDecodingContext *ctx,
 											ReorderBufferTXN *txn,
 											XLogRecPtr abort_lsn);
 
 /*
  * Called to prepare changes streamed to remote node from in-progress
- * transaction. This is called as part of a two-phase commit.
+ * transaction. This is called as part of a two-phase commit.  Should return true
+ * if the transaction is output, false otherwise.
  */
-typedef void (*LogicalDecodeStreamPrepareCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamPrepareCB) (struct LogicalDecodingContext *ctx,
 											  ReorderBufferTXN *txn,
 											  XLogRecPtr prepare_lsn);
 
 /*
- * Called to apply changes streamed to remote node from in-progress
- * transaction.
+ * Called to apply changes streamed to remote node from in-progress transaction.
+ * Should return true if the transaction is output, false otherwise.
  */
-typedef void (*LogicalDecodeStreamCommitCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamCommitCB) (struct LogicalDecodingContext *ctx,
 											 ReorderBufferTXN *txn,
 											 XLogRecPtr commit_lsn);
 
 /*
  * Callback for streaming individual changes from in-progress transactions.
+ * Should return true if the change is output, false otherwise.
  */
-typedef void (*LogicalDecodeStreamChangeCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamChangeCB) (struct LogicalDecodingContext *ctx,
 											 ReorderBufferTXN *txn,
 											 Relation relation,
 											 ReorderBufferChange *change);
@@ -202,9 +208,10 @@ typedef void (*LogicalDecodeStreamMessageCB) (struct LogicalDecodingContext *ctx
 											  const char *message);
 
 /*
- * Callback for streaming truncates from in-progress transactions.
+ * Callback for streaming truncates from in-progress transactions. Should return
+ * true if the change is output, false otherwise.
  */
-typedef void (*LogicalDecodeStreamTruncateCB) (struct LogicalDecodingContext *ctx,
+typedef bool (*LogicalDecodeStreamTruncateCB) (struct LogicalDecodingContext *ctx,
 											   ReorderBufferTXN *txn,
 											   int nrelations,
 											   Relation relations[],
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
index 3cbe106a3c7..bd4c17da7ac 100644
--- a/src/include/replication/reorderbuffer.h
+++ b/src/include/replication/reorderbuffer.h
@@ -699,6 +699,11 @@ struct ReorderBuffer
 	 */
 	int64		totalTxns;		/* total number of transactions sent */
 	int64		totalBytes;		/* total amount of data decoded */
+	int64		sentTxns;		/* number of transactions decoded and sent
+								 * downstream */
+	int64		sentBytes;		/* amount of data decoded and sent downstream */
+	int64		filteredBytes;	/* amount of data filtered out by output
+								 * plugin */
 };
 
 
@@ -718,6 +723,7 @@ extern void ReorderBufferFreeRelids(ReorderBuffer *rb, Oid *relids);
 extern void ReorderBufferQueueChange(ReorderBuffer *rb, TransactionId xid,
 									 XLogRecPtr lsn, ReorderBufferChange *change,
 									 bool toast_insert);
+extern Size ReorderBufferChangeSize(ReorderBufferChange *change);
 extern void ReorderBufferQueueMessage(ReorderBuffer *rb, TransactionId xid,
 									  Snapshot snap, XLogRecPtr lsn,
 									  bool transactional, const char *prefix,
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index 96b70b84d5e..c8ada58379b 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -214,10 +214,10 @@ my $stats_test_slot2 = 'logical_slot';
 # Stats exist for stats test slot 1
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT total_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT total_wal_bytes > 0, sent_bytes > 0, stats_reset IS NULL FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Total bytes is > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
+	qq(t|t|t),
+	qq(Total bytes and plugin sent bytes are both > 0 and stats_reset is NULL for slot '$stats_test_slot1'.)
 );
 
 # Do reset of stats for stats test slot 1
@@ -235,10 +235,10 @@ $node_primary->safe_psql('postgres',
 
 is( $node_primary->safe_psql(
 		'postgres',
-		qq(SELECT stats_reset > '$reset1'::timestamptz, total_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
+		qq(SELECT stats_reset > '$reset1'::timestamptz, total_wal_bytes = 0, sent_bytes = 0 FROM pg_stat_replication_slots WHERE slot_name = '$stats_test_slot1')
 	),
-	qq(t|t),
-	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_bytes was set to 0.)
+	qq(t|t|t),
+	qq(Check that reset timestamp is later after the second reset of stats for slot '$stats_test_slot1' and confirm total_wal_bytes and sent_bytes were set to 0.)
 );
 
 # Check that test slot 2 has NULL in reset timestamp
diff --git a/src/test/recovery/t/035_standby_logical_decoding.pl b/src/test/recovery/t/035_standby_logical_decoding.pl
index ebe2fae1789..5f4df30d65a 100644
--- a/src/test/recovery/t/035_standby_logical_decoding.pl
+++ b/src/test/recovery/t/035_standby_logical_decoding.pl
@@ -577,7 +577,7 @@ $node_primary->safe_psql('testdb',
 	qq[INSERT INTO decoding_test(x,y) SELECT 100,'100';]);
 
 $node_standby->poll_query_until('testdb',
-	qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+	qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 ) or die "replication slot stats of vacuum_full_activeslot not updated";
 
 # This should trigger the conflict
@@ -605,7 +605,7 @@ ok( $stderr =~
 # Ensure that replication slot stats are not removed after invalidation.
 is( $node_standby->safe_psql(
 		'testdb',
-		qq[SELECT total_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
+		qq[SELECT total_wal_txns > 0 FROM pg_stat_replication_slots WHERE slot_name = 'vacuum_full_activeslot']
 	),
 	't',
 	'replication slot stats not removed after invalidation');
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 4286c266e17..9801c66fba8 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2160,6 +2160,7 @@ pg_stat_replication| SELECT s.pid,
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_lsn, write_lsn, flush_lsn, replay_lsn, write_lag, flush_lag, replay_lag, sync_priority, sync_state, reply_time) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_replication_slots| SELECT s.slot_name,
+    r.plugin,
     s.spill_txns,
     s.spill_count,
     s.spill_bytes,
@@ -2167,13 +2168,16 @@ pg_stat_replication_slots| SELECT s.slot_name,
     s.stream_count,
     s.stream_bytes,
     s.mem_exceeded_count,
-    s.total_txns,
-    s.total_bytes,
+    s.total_wal_txns,
+    s.total_wal_bytes,
+    s.filtered_bytes,
+    s.sent_txns,
+    s.sent_bytes,
     s.slotsync_skip_count,
     s.slotsync_last_skip,
     s.stats_reset
    FROM pg_replication_slots r,
-    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, mem_exceeded_count, total_txns, total_bytes, slotsync_skip_count, slotsync_last_skip, stats_reset)
+    LATERAL pg_stat_get_replication_slot((r.slot_name)::text) s(slot_name, spill_txns, spill_count, spill_bytes, stream_txns, stream_count, stream_bytes, mem_exceeded_count, total_wal_txns, total_wal_bytes, filtered_bytes, sent_txns, sent_bytes, slotsync_skip_count, slotsync_last_skip, stats_reset)
   WHERE (r.datoid IS NOT NULL);
 pg_stat_slru| SELECT name,
     blks_zeroed,
diff --git a/src/test/subscription/t/001_rep_changes.pl b/src/test/subscription/t/001_rep_changes.pl
index 430c1246d14..68501aa6ad5 100644
--- a/src/test/subscription/t/001_rep_changes.pl
+++ b/src/test/subscription/t/001_rep_changes.pl
@@ -124,6 +124,9 @@ $result =
   $node_subscriber->safe_psql('postgres', "SELECT count(*) FROM tab_ins");
 is($result, qq(1002), 'check initial data was copied to subscriber');
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_ins SELECT generate_series(1,50)");
 $node_publisher->safe_psql('postgres', "DELETE FROM tab_ins WHERE a > 20");
@@ -157,6 +160,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup('tap_sub');
 
+# Verify that filtered_bytes increased due to filtered update and delete
+# operations on tab_ins.  We cannot test the exact value since it may include
+# changes from other concurrent transactions.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'filtered_bytes increased after DML filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab_ins");
 is($result, qq(1052|1|1002), 'check replicated inserts on subscriber');
diff --git a/src/test/subscription/t/010_truncate.pl b/src/test/subscription/t/010_truncate.pl
index 3d16c2a800d..011c931dbd3 100644
--- a/src/test/subscription/t/010_truncate.pl
+++ b/src/test/subscription/t/010_truncate.pl
@@ -69,6 +69,9 @@ $node_subscriber->safe_psql('postgres',
 # Wait for initial sync of all subscriptions
 $node_subscriber->wait_for_subscription_sync;
 
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+
 # insert data to truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -98,6 +101,16 @@ $node_publisher->wait_for_catchup('sub1');
 $result = $node_subscriber->safe_psql('postgres', "SELECT nextval('seq1')");
 is($result, qq(101), 'truncate restarted identities');
 
+# All the DMLs above happen on tables that are subscribed to by sub1 and not
+# sub2. filtered_bytes should get incremented for replication slot
+# corresponding to the subscription sub2. We can not test the exact value of
+# filtered_bytes because the counter is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'filtered_bytes increased after publication level filtering');
+$initial_filtered_bytes = $final_filtered_bytes;
+
 # test publication that does not replicate truncate
 
 $node_subscriber->safe_psql('postgres',
@@ -107,6 +120,13 @@ $node_publisher->safe_psql('postgres', "TRUNCATE tab2");
 
 $node_publisher->wait_for_catchup('sub2');
 
+# Truncate changes are filtered out at publication level itself. Make sure that
+# the filtered_bytes is incremented.
+$final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'sub2'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'filtered_bytes increased after truncate filtering');
+
 $result = $node_subscriber->safe_psql('postgres',
 	"SELECT count(*), min(a), max(a) FROM tab2");
 is($result, qq(3|1|3), 'truncate not replicated');
diff --git a/src/test/subscription/t/028_row_filter.pl b/src/test/subscription/t/028_row_filter.pl
index e2c83670053..b772676d6bc 100644
--- a/src/test/subscription/t/028_row_filter.pl
+++ b/src/test/subscription/t/028_row_filter.pl
@@ -579,6 +579,9 @@ is($result, qq(3|6),
 # commands are for testing normal logical replication behavior.
 #
 # test row filter (INSERT, UPDATE, DELETE)
+my $initial_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+
 $node_publisher->safe_psql('postgres',
 	"INSERT INTO tab_rowfilter_1 (a, b) VALUES (800, 'test 800')");
 $node_publisher->safe_psql('postgres',
@@ -612,6 +615,14 @@ $node_publisher->safe_psql('postgres',
 
 $node_publisher->wait_for_catchup($appname);
 
+# The changes which do not pass the row filter will be filtered. Make sure that
+# the filtered_bytes reflects that. We can not test the exact value of
+# filtered_bytes since it is affected by background activity.
+my $final_filtered_bytes = $node_publisher->safe_psql('postgres',
+	"SELECT filtered_bytes FROM pg_stat_replication_slots WHERE slot_name = 'tap_sub'");
+cmp_ok($final_filtered_bytes, '>', $initial_filtered_bytes,
+	'filtered_bytes increased after row filtering');
+
 # Check expected replicated rows for tab_rowfilter_2
 # tap_pub_1 filter is: (c % 2 = 0)
 # tap_pub_2 filter is: (c % 3 = 0)

base-commit: 1362bc33e025fd2848ff38558f5672e2f0f0c7de
-- 
2.34.1