New function pg_stat_statements_reset_query() to reset statistics of a specific query

From f017a98c179040cbc84ba3fbd164375b99359ea3 Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Fri, 29 Jun 2018 01:17:41 +1000
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Based on the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will relese all entries as per the
old behaviour.
---
 contrib/pg_stat_statements/Makefile                |   8 +-
 .../expected/pg_stat_statements.out                | 136 +++++++++++++++++++++
 .../pg_stat_statements--1.5--1.6.sql               |  24 ++++
 contrib/pg_stat_statements/pg_stat_statements.c    | 101 ++++++++++-----
 .../pg_stat_statements/pg_stat_statements.control  |   2 +-
 .../pg_stat_statements/sql/pg_stat_statements.sql  |  44 +++++++
 doc/src/sgml/pgstatstatements.sgml                 |  10 +-
 7 files changed, 287 insertions(+), 38 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 39b368b70e..f0942f829e 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.4--1.5.sql \
-	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
-	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
-	pg_stat_statements--unpackaged--1.0.sql
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
+	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
+	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
+	pg_stat_statements--1.0--1.1.sql pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
 LDFLAGS_SL += $(filter -lm, $(LIBS))
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..7bd330eb95 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,140 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+SET ROLE stats_regress_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                    query                                     | calls | rows 
+------------------------------------------------------------------------------+-------+------
+ CREATE INDEX test_b ON test(b)                                               |     1 |    0
+ CREATE ROLE stats_regress_user1                                              |     1 |    0
+ CREATE ROLE stats_regress_user2                                              |     1 |    0
+ DROP FUNCTION IF EXISTS PLUS_ONE(INTEGER)                                    |     1 |    0
+ DROP FUNCTION PLUS_ONE(INTEGER)                                              |     1 |    0
+ DROP FUNCTION PLUS_TWO(INTEGER)                                              |     1 |    0
+ DROP TABLE IF EXISTS test                                                    |     3 |    0
+ DROP TABLE test                                                              |     1 |    0
+ RESET ROLE                                                                   |     2 |    0
+ SELECT $1                                                                    |     1 |    1
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT pg_stat_statements_reset()                                            |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C" |     1 |    8
+ SET ROLE stats_regress_user1                                                 |     1 |    0
+ SET ROLE stats_regress_user2                                                 |     1 |    0
+(18 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE INDEX test_b ON test(b)                                                                   |     1 |    0
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ DROP FUNCTION IF EXISTS PLUS_ONE(INTEGER)                                                        |     1 |    0
+ DROP FUNCTION PLUS_ONE(INTEGER)                                                                  |     1 |    0
+ DROP FUNCTION PLUS_TWO(INTEGER)                                                                  |     1 |    0
+ DROP TABLE IF EXISTS test                                                                        |     3 |    0
+ DROP TABLE test                                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   26
+ SET ROLE stats_regress_user1                                                                     |     1 |    0
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(16 rows)
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE INDEX test_b ON test(b)                                                                   |     1 |    0
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ DROP FUNCTION IF EXISTS PLUS_ONE(INTEGER)                                                        |     1 |    0
+ DROP FUNCTION PLUS_ONE(INTEGER)                                                                  |     1 |    0
+ DROP FUNCTION PLUS_TWO(INTEGER)                                                                  |     1 |    0
+ DROP TABLE IF EXISTS test                                                                        |     3 |    0
+ DROP TABLE test                                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     3 |   42
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(15 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
new file mode 100644
index 0000000000..4f3f608032
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
@@ -0,0 +1,24 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.6'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT 0,
+	IN dbid Oid DEFAULT 0,
+	IN queryid bigint DEFAULT 0
+)
+RETURNS void
+AS 'MODULE_PATHNAME'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) TO pg_read_all_stats;
+
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index cc9efab243..007bad08a6 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -327,7 +327,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1293,16 +1293,26 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics according to userid, dbid, queryid.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+
 	if (!pgss || !pgss_hash)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+
+	userid = PG_GETARG_OID(0);
+	dbid = PG_GETARG_OID(1);
+	queryid = (uint64) PG_GETARG_INT64(2);
+	entry_reset(userid, dbid, queryid);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,50 +2239,81 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries according to parameters.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	/* If all parameter available, use the fast path */
+	if (userid != 0 && dbid != 0 && queryid != 0)
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key out of hash if available */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
 	}
-
-	/*
-	 * Write new empty query file, perhaps even creating a new one to recover
-	 * if the file was missing.
-	 */
-	qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
-	if (qfile == NULL)
+	else
 	{
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not create pg_stat_statement file \"%s\": %m",
-						PGSS_TEXT_FILE)));
-		goto done;
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || (userid && entry->key.userid == userid)) &&
+				(!dbid || (dbid && entry->key.dbid == dbid)) &&
+				(!queryid || (queryid && entry->key.queryid == queryid)))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
 	}
 
-	/* If ftruncate fails, log it, but it's not a fatal problem */
-	if (ftruncate(fileno(qfile), 0) != 0)
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not truncate pg_stat_statement file \"%s\": %m",
-						PGSS_TEXT_FILE)));
+	if (!num_remove)
+		ereport(LOG, (errmsg("userid %u, dbid %u, queryid %ld does not exist", userid, dbid, queryid)));
 
-	FreeFile(qfile);
+	if (num_entries == num_remove)
+	{
+		/*
+		 * Write new empty query file, perhaps even creating a new one to
+		 * recover if the file was missing.
+		 */
+		qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
+		if (qfile == NULL)
+		{
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not create pg_stat_statement file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+			goto done;
+		}
+
+		/* If ftruncate fails, log it, but it's not a fatal problem */
+		if (ftruncate(fileno(qfile), 0) != 0)
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not truncate pg_stat_statement file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+
+		FreeFile(qfile);
 
 done:
-	pgss->extent = 0;
-	/* This counts as a query text garbage collection for our purposes */
-	record_gc_qtexts();
+		pgss->extent = 0;
+		/* This counts as a query text garbage collection for our purposes */
+		record_gc_qtexts();
+	}
 
 	LWLockRelease(pgss->lock);
 }
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 193fcdfafa..617038b4c0 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.5'
+default_version = '1.6'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..32d6a3154a 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,48 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+
+SET ROLE stats_regress_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..9561b2d408 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,8 +344,12 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> according to 
+      the specified userid, dbid and queryid. If any of the parameter is not
+      specified, the default value 0(invalid) is used and the statistics that
+      match with other parameter(s) will be reset. If no parameter is specified
+      or specify everything as 0(invalid), it will discard all statistics.
       By default, this function can only be executed by superusers.
      </para>
     </listitem>
-- 
2.16.1.windows.4

From 929f10c0a5b99636373ccb50445e9b6d74c9fc3b Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Fri, 29 Jun 2018 01:17:41 +1000
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Based on the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.

Backward Compatible change, Now pg_stat_statements_reset() function
returns the number of statement entries that are reset.
---
 contrib/pg_stat_statements/Makefile                |   8 +-
 .../expected/pg_stat_statements.out                | 134 ++++++++++++++++++++-
 .../pg_stat_statements--1.5--1.6.sql               |  24 ++++
 contrib/pg_stat_statements/pg_stat_statements.c    | 120 +++++++++++++-----
 .../pg_stat_statements/pg_stat_statements.control  |   2 +-
 .../pg_stat_statements/sql/pg_stat_statements.sql  |  45 +++++++
 doc/src/sgml/pgstatstatements.sgml                 |  14 ++-
 7 files changed, 301 insertions(+), 46 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 39b368b70e..f0942f829e 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.4--1.5.sql \
-	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
-	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
-	pg_stat_statements--unpackaged--1.0.sql
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
+	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
+	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
+	pg_stat_statements--1.0--1.1.sql pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
 LDFLAGS_SL += $(filter -lm, $(LIBS))
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..4e2ef7719a 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -6,7 +6,7 @@ SET pg_stat_statements.track_utility = FALSE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "int";
@@ -122,7 +122,7 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       12
 (1 row)
 
 -- utility "create table" should not be shown
@@ -216,7 +216,7 @@ SET pg_stat_statements.track = 'none';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "one";
@@ -243,7 +243,7 @@ SET pg_stat_statements.track = 'top';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        2
 (1 row)
 
 DO LANGUAGE plpgsql $$
@@ -303,7 +303,7 @@ SET pg_stat_statements.track = 'all';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        7
 (1 row)
 
 -- we drop and recreate the functions to avoid any caching funnies
@@ -361,7 +361,7 @@ SET pg_stat_statements.track_utility = TRUE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        6
 (1 row)
 
 SELECT 1;
@@ -395,4 +395,126 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+SET ROLE stats_regress_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE stats_regress_user1   |     1 |    0
+ CREATE ROLE stats_regress_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE stats_regress_user1      |     1 |    0
+ SET ROLE stats_regress_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+                        0
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE stats_regress_user1                                                                     |     1 |    0
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
new file mode 100644
index 0000000000..81ac627f37
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
@@ -0,0 +1,24 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.6'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS bigint
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_6'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) TO pg_read_all_stats;
+
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index cc9efab243..97d259165f 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_6);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static long entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1293,7 +1294,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics according to userid, dbid, queryid.
+ */
+Datum
+pg_stat_statements_reset_1_6(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+	int64		num_remove;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
+
+	userid = PG_GETARG_OID(0);
+	dbid = PG_GETARG_OID(1);
+	queryid = (uint64) PG_GETARG_INT64(2);
+
+	num_remove = entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_INT64(num_remove);
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
@@ -1302,7 +1328,9 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,52 +2257,82 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries according to parameters.
  */
-static void
-entry_reset(void)
+static long
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	/* If all parameter available, use the fast path */
+	if (userid != 0 && dbid != 0 && queryid != 0)
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key out of hash if available */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
 	}
-
-	/*
-	 * Write new empty query file, perhaps even creating a new one to recover
-	 * if the file was missing.
-	 */
-	qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
-	if (qfile == NULL)
+	else
 	{
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not create pg_stat_statement file \"%s\": %m",
-						PGSS_TEXT_FILE)));
-		goto done;
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || (userid && entry->key.userid == userid)) &&
+				(!dbid || (dbid && entry->key.dbid == dbid)) &&
+				(!queryid || (queryid && entry->key.queryid == queryid)))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
 	}
 
-	/* If ftruncate fails, log it, but it's not a fatal problem */
-	if (ftruncate(fileno(qfile), 0) != 0)
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not truncate pg_stat_statement file \"%s\": %m",
-						PGSS_TEXT_FILE)));
+	if (num_entries == num_remove)
+	{
+		/*
+		 * Write new empty query file, perhaps even creating a new one to
+		 * recover if the file was missing.
+		 */
+		qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
+		if (qfile == NULL)
+		{
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not create pg_stat_statement file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+			goto done;
+		}
 
-	FreeFile(qfile);
+		/* If ftruncate fails, log it, but it's not a fatal problem */
+		if (ftruncate(fileno(qfile), 0) != 0)
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not truncate pg_stat_statement file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+
+		FreeFile(qfile);
 
 done:
-	pgss->extent = 0;
-	/* This counts as a query text garbage collection for our purposes */
-	record_gc_qtexts();
+		pgss->extent = 0;
+		/* This counts as a query text garbage collection for our purposes */
+		record_gc_qtexts();
+	}
 
 	LWLockRelease(pgss->lock);
+
+	return num_remove;
 }
 
 /*
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 193fcdfafa..617038b4c0 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.5'
+default_version = '1.6'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..c027b6c540 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,49 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+
+SET ROLE stats_regress_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..2d11b9ea1e 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,15 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> according to 
+      the specified userid, dbid and queryid. If any of the parameter is not
+      specified, the default value NULL(invalid) is used and the statistics that
+      match with other parameter(s) will be reset. If no parameter is specified
+      or specify everything as NULL(invalid), it will discard all statistics.
+      By default, this function can only be executed by superusers and members
+      of the <literal>pg_read_all_stats</literal> role. Access may be granted
+      to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.16.1.windows.4

From f3d4c1a319ceefafabd45039b4b3447fb126e91c Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Fri, 29 Jun 2018 01:17:41 +1000
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Based on the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.

Backward Compatible change, Now pg_stat_statements_reset() function
returns the number of statement entries that are reset.
---
 contrib/pg_stat_statements/Makefile                |   8 +-
 .../expected/pg_stat_statements.out                | 134 ++++++++++++++++++++-
 .../pg_stat_statements--1.5--1.6.sql               |  24 ++++
 contrib/pg_stat_statements/pg_stat_statements.c    | 120 +++++++++++++-----
 .../pg_stat_statements/pg_stat_statements.control  |   2 +-
 .../pg_stat_statements/sql/pg_stat_statements.sql  |  45 +++++++
 doc/src/sgml/pgstatstatements.sgml                 |  16 ++-
 7 files changed, 303 insertions(+), 46 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 39b368b70e..f0942f829e 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.4--1.5.sql \
-	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
-	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
-	pg_stat_statements--unpackaged--1.0.sql
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
+	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
+	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
+	pg_stat_statements--1.0--1.1.sql pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
 LDFLAGS_SL += $(filter -lm, $(LIBS))
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..4e2ef7719a 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -6,7 +6,7 @@ SET pg_stat_statements.track_utility = FALSE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "int";
@@ -122,7 +122,7 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       12
 (1 row)
 
 -- utility "create table" should not be shown
@@ -216,7 +216,7 @@ SET pg_stat_statements.track = 'none';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "one";
@@ -243,7 +243,7 @@ SET pg_stat_statements.track = 'top';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        2
 (1 row)
 
 DO LANGUAGE plpgsql $$
@@ -303,7 +303,7 @@ SET pg_stat_statements.track = 'all';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        7
 (1 row)
 
 -- we drop and recreate the functions to avoid any caching funnies
@@ -361,7 +361,7 @@ SET pg_stat_statements.track_utility = TRUE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        6
 (1 row)
 
 SELECT 1;
@@ -395,4 +395,126 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+SET ROLE stats_regress_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE stats_regress_user1   |     1 |    0
+ CREATE ROLE stats_regress_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE stats_regress_user1      |     1 |    0
+ SET ROLE stats_regress_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+                        0
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE stats_regress_user1                                                                     |     1 |    0
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
new file mode 100644
index 0000000000..81ac627f37
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
@@ -0,0 +1,24 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.6'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS bigint
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_6'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) TO pg_read_all_stats;
+
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index cc9efab243..df3b1ce867 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_6);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static long entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1293,7 +1294,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics according to userid, dbid, queryid.
+ */
+Datum
+pg_stat_statements_reset_1_6(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+	int64		num_remove;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	num_remove = entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_INT64(num_remove);
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
@@ -1302,7 +1328,9 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,52 +2257,82 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries according to parameters.
  */
-static void
-entry_reset(void)
+static long
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	/* If all parameter available, use the fast path */
+	if (userid != 0 && dbid != 0 && queryid != 0)
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key out of hash if available */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
 	}
-
-	/*
-	 * Write new empty query file, perhaps even creating a new one to recover
-	 * if the file was missing.
-	 */
-	qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
-	if (qfile == NULL)
+	else
 	{
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not create pg_stat_statement file \"%s\": %m",
-						PGSS_TEXT_FILE)));
-		goto done;
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || (userid && entry->key.userid == userid)) &&
+				(!dbid || (dbid && entry->key.dbid == dbid)) &&
+				(!queryid || (queryid && entry->key.queryid == queryid)))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
 	}
 
-	/* If ftruncate fails, log it, but it's not a fatal problem */
-	if (ftruncate(fileno(qfile), 0) != 0)
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not truncate pg_stat_statement file \"%s\": %m",
-						PGSS_TEXT_FILE)));
+	if (num_entries == num_remove)
+	{
+		/*
+		 * Write new empty query file, perhaps even creating a new one to
+		 * recover if the file was missing.
+		 */
+		qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
+		if (qfile == NULL)
+		{
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not create pg_stat_statement file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+			goto done;
+		}
 
-	FreeFile(qfile);
+		/* If ftruncate fails, log it, but it's not a fatal problem */
+		if (ftruncate(fileno(qfile), 0) != 0)
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not truncate pg_stat_statement file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+
+		FreeFile(qfile);
 
 done:
-	pgss->extent = 0;
-	/* This counts as a query text garbage collection for our purposes */
-	record_gc_qtexts();
+		pgss->extent = 0;
+		/* This counts as a query text garbage collection for our purposes */
+		record_gc_qtexts();
+	}
 
 	LWLockRelease(pgss->lock);
+
+	return num_remove;
 }
 
 /*
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 193fcdfafa..617038b4c0 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.5'
+default_version = '1.6'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..c027b6c540 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,49 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+
+SET ROLE stats_regress_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..8432e4bb84 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns bigint</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,17 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> according to 
+      the specified userid, dbid and queryid. Returns the total number of
+      statement statistics that are reset based on the specified input.
+      If any of the parameter is not specified, the default value NULL(invalid)
+      is used and the statistics that match with other parameter(s) will be reset.
+      If no parameter is specified or specify everything as NULL(invalid), it will
+      discard all statistics.
+      By default, this function can only be executed by superusers and members
+      of the <literal>pg_read_all_stats</literal> role. Access may be granted
+      to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.16.1.windows.4

From 83d1a63b822a3242f95200bd85e9eadd72db1e20 Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Mon, 9 Jul 2018 15:15:09 +1000
Subject: [PATCH] Revoke pg_stat_statements_reset() permissions

Commit 25fff40798 has granted the execute permissions of the
pg_stat_statements_reset() function to "pg_read_all_stats" role.
As this role is meant to read the stats, but not to reset.
So revoke the permissions on reset() function from public.
---
 contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql | 7 +++++++
 contrib/pg_stat_statements/pg_stat_statements.control       | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql

diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
new file mode 100644
index 0000000000..5f897f74dc
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
@@ -0,0 +1,7 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.6'" to load this file. \quit
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset() FROM PUBLIC;
\ No newline at end of file
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 193fcdfafa..617038b4c0 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.5'
+default_version = '1.6'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
-- 
2.16.1.windows.4

From cb5b8904d6a7293dd08f3b10045de182efc9b5dd Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Mon, 9 Jul 2018 15:15:09 +1000
Subject: [PATCH] Revoke pg_stat_statements_reset() permissions

Commit 25fff40798 has granted the execute permissions of the
pg_stat_statements_reset() function to "pg_read_all_stats" role.
As this role is meant to read the stats, but not to reset.
So revoke the permissions on reset() function from "pg_read_all_stats".
---
 contrib/pg_stat_statements/Makefile                         | 3 ++-
 contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql | 7 +++++++
 contrib/pg_stat_statements/pg_stat_statements.control       | 2 +-
 3 files changed, 10 insertions(+), 2 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 39b368b70e..b1f9954bd6 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,7 +4,8 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.4--1.5.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
+	pg_stat_statements--1.4--1.5.sql \
 	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
 	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
new file mode 100644
index 0000000000..1b7e081fe9
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
@@ -0,0 +1,7 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.6'" to load this file. \quit
+
+-- Don't want this to be available to non-superusers.
+REVOKE EXECUTE ON FUNCTION pg_stat_statements_reset() FROM pg_read_all_stats;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 193fcdfafa..617038b4c0 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.5'
+default_version = '1.6'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
-- 
2.16.1.windows.4

From 1de1e47f70c845ca387f689139b7971dba82b3e3 Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Fri, 29 Jun 2018 01:17:41 +1000
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Based on the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.

Backward Compatible change, Now pg_stat_statements_reset() function
returns the number of statement entries that are reset.
---
 contrib/pg_stat_statements/Makefile                |   4 +-
 .../expected/pg_stat_statements.out                | 134 ++++++++++++++++++++-
 .../pg_stat_statements--1.6--1.7.sql               |  23 ++++
 contrib/pg_stat_statements/pg_stat_statements.c    | 129 +++++++++++++++-----
 .../pg_stat_statements/pg_stat_statements.control  |   2 +-
 .../pg_stat_statements/sql/pg_stat_statements.sql  |  45 +++++++
 doc/src/sgml/pgstatstatements.sgml                 |  15 ++-
 7 files changed, 308 insertions(+), 44 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index b1f9954bd6..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,8 +4,8 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
 	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
 	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..4e2ef7719a 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -6,7 +6,7 @@ SET pg_stat_statements.track_utility = FALSE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "int";
@@ -122,7 +122,7 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       12
 (1 row)
 
 -- utility "create table" should not be shown
@@ -216,7 +216,7 @@ SET pg_stat_statements.track = 'none';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "one";
@@ -243,7 +243,7 @@ SET pg_stat_statements.track = 'top';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        2
 (1 row)
 
 DO LANGUAGE plpgsql $$
@@ -303,7 +303,7 @@ SET pg_stat_statements.track = 'all';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        7
 (1 row)
 
 -- we drop and recreate the functions to avoid any caching funnies
@@ -361,7 +361,7 @@ SET pg_stat_statements.track_utility = TRUE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        6
 (1 row)
 
 SELECT 1;
@@ -395,4 +395,126 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+SET ROLE stats_regress_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE stats_regress_user1   |     1 |    0
+ CREATE ROLE stats_regress_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE stats_regress_user1      |     1 |    0
+ SET ROLE stats_regress_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+                        0
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE stats_regress_user1                                                                     |     1 |    0
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..4026fd777d
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,23 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS bigint
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
+
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index cc9efab243..d17f5ab84c 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static long entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,7 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics according to userid, dbid, queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+	int64		num_remove;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	num_remove = entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_INT64(num_remove);
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
@@ -1302,7 +1337,9 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,52 +2266,82 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries according to parameters.
  */
-static void
-entry_reset(void)
+static long
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	/* If all parameter available, use the fast path */
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key out of hash if available */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
 	}
-
-	/*
-	 * Write new empty query file, perhaps even creating a new one to recover
-	 * if the file was missing.
-	 */
-	qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
-	if (qfile == NULL)
+	else
 	{
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not create pg_stat_statement file \"%s\": %m",
-						PGSS_TEXT_FILE)));
-		goto done;
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || (userid && entry->key.userid == userid)) &&
+				(!dbid || (dbid && entry->key.dbid == dbid)) &&
+				(!queryid || (queryid && entry->key.queryid == queryid)))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
 	}
 
-	/* If ftruncate fails, log it, but it's not a fatal problem */
-	if (ftruncate(fileno(qfile), 0) != 0)
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not truncate pg_stat_statement file \"%s\": %m",
-						PGSS_TEXT_FILE)));
+	if (num_entries == num_remove)
+	{
+		/*
+		 * Write new empty query file, perhaps even creating a new one to
+		 * recover if the file was missing.
+		 */
+		qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
+		if (qfile == NULL)
+		{
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not create pg_stat_statement file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+			goto done;
+		}
 
-	FreeFile(qfile);
+		/* If ftruncate fails, log it, but it's not a fatal problem */
+		if (ftruncate(fileno(qfile), 0) != 0)
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not truncate pg_stat_statement file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+
+		FreeFile(qfile);
 
 done:
-	pgss->extent = 0;
-	/* This counts as a query text garbage collection for our purposes */
-	record_gc_qtexts();
+		pgss->extent = 0;
+		/* This counts as a query text garbage collection for our purposes */
+		record_gc_qtexts();
+	}
 
 	LWLockRelease(pgss->lock);
+
+	return num_remove;
 }
 
 /*
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..c027b6c540 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,49 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+
+SET ROLE stats_regress_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..d091dcecd1 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns bigint</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> according to 
+      the specified userid, dbid and queryid. Returns the total number of
+      statement statistics that are reset based on the specified input.
+      If any of the parameter is not specified, the default value NULL(invalid)
+      is used and the statistics that match with other parameter(s) will be reset.
+      If no parameter is specified or specify everything as NULL(invalid), it will
+      discard all statistics.
+      By default, this function can only be executed by superusers. Access may
+      be granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.16.1.windows.4

From cb5b8904d6a7293dd08f3b10045de182efc9b5dd Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Mon, 9 Jul 2018 15:15:09 +1000
Subject: [PATCH] Revoke pg_stat_statements_reset() permissions

Commit 25fff40798 has granted the execute permissions of the
pg_stat_statements_reset() function to "pg_read_all_stats" role.
As this role is meant to read the stats, but not to reset.
So revoke the permissions on reset() function from "pg_read_all_stats".
---
 contrib/pg_stat_statements/Makefile                         | 3 ++-
 contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql | 7 +++++++
 contrib/pg_stat_statements/pg_stat_statements.control       | 2 +-
 3 files changed, 10 insertions(+), 2 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 39b368b70e..b1f9954bd6 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,7 +4,8 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.4--1.5.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
+	pg_stat_statements--1.4--1.5.sql \
 	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
 	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
new file mode 100644
index 0000000000..1b7e081fe9
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql
@@ -0,0 +1,7 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.5--1.6.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.6'" to load this file. \quit
+
+-- Don't want this to be available to non-superusers.
+REVOKE EXECUTE ON FUNCTION pg_stat_statements_reset() FROM pg_read_all_stats;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 193fcdfafa..617038b4c0 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.5'
+default_version = '1.6'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
-- 
2.16.1.windows.4

From 6cfe73412c845df91af18029d7af4bc90958b942 Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Fri, 29 Jun 2018 01:17:41 +1000
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Based on the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.

Backward Compatible change, Now pg_stat_statements_reset() function
returns the number of statement entries that are reset.
---
 contrib/pg_stat_statements/Makefile           |   4 +-
 .../expected/pg_stat_statements.out           | 134 +++++++++++++++++-
 .../pg_stat_statements--1.6--1.7.sql          |  23 +++
 .../pg_stat_statements/pg_stat_statements.c   | 129 +++++++++++++----
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  45 ++++++
 doc/src/sgml/pgstatstatements.sgml            |  15 +-
 7 files changed, 308 insertions(+), 44 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index b1f9954bd6..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,8 +4,8 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
 	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
 	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..4e2ef7719a 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -6,7 +6,7 @@ SET pg_stat_statements.track_utility = FALSE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "int";
@@ -122,7 +122,7 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       12
 (1 row)
 
 -- utility "create table" should not be shown
@@ -216,7 +216,7 @@ SET pg_stat_statements.track = 'none';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "one";
@@ -243,7 +243,7 @@ SET pg_stat_statements.track = 'top';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        2
 (1 row)
 
 DO LANGUAGE plpgsql $$
@@ -303,7 +303,7 @@ SET pg_stat_statements.track = 'all';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        7
 (1 row)
 
 -- we drop and recreate the functions to avoid any caching funnies
@@ -361,7 +361,7 @@ SET pg_stat_statements.track_utility = TRUE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        6
 (1 row)
 
 SELECT 1;
@@ -395,4 +395,126 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+SET ROLE stats_regress_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE stats_regress_user1   |     1 |    0
+ CREATE ROLE stats_regress_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE stats_regress_user1      |     1 |    0
+ SET ROLE stats_regress_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+                        0
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE stats_regress_user1                                                                     |     1 |    0
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE stats_regress_user1                                                                  |     1 |    0
+ CREATE ROLE stats_regress_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE stats_regress_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..4026fd777d
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,23 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS bigint
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
+
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79f54..61b166e597 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static long entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,7 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics according to userid, dbid, queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+	int64		num_remove;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	num_remove = entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_INT64(num_remove);
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
@@ -1302,7 +1337,9 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,52 +2266,82 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries according to parameters.
  */
-static void
-entry_reset(void)
+static long
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	/* If all parameter available, use the fast path */
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key out of hash if available */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
 	}
-
-	/*
-	 * Write new empty query file, perhaps even creating a new one to recover
-	 * if the file was missing.
-	 */
-	qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
-	if (qfile == NULL)
+	else
 	{
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not create file \"%s\": %m",
-						PGSS_TEXT_FILE)));
-		goto done;
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || (userid && entry->key.userid == userid)) &&
+				(!dbid || (dbid && entry->key.dbid == dbid)) &&
+				(!queryid || (queryid && entry->key.queryid == queryid)))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
 	}
 
-	/* If ftruncate fails, log it, but it's not a fatal problem */
-	if (ftruncate(fileno(qfile), 0) != 0)
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not truncate file \"%s\": %m",
-						PGSS_TEXT_FILE)));
+	if (num_entries == num_remove)
+	{
+		/*
+		 * Write new empty query file, perhaps even creating a new one to
+		 * recover if the file was missing.
+		 */
+		qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
+		if (qfile == NULL)
+		{
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not create file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+			goto done;
+		}
 
-	FreeFile(qfile);
+		/* If ftruncate fails, log it, but it's not a fatal problem */
+		if (ftruncate(fileno(qfile), 0) != 0)
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not truncate file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+
+		FreeFile(qfile);
 
 done:
-	pgss->extent = 0;
-	/* This counts as a query text garbage collection for our purposes */
-	record_gc_qtexts();
+		pgss->extent = 0;
+		/* This counts as a query text garbage collection for our purposes */
+		record_gc_qtexts();
+	}
 
 	LWLockRelease(pgss->lock);
+
+	return num_remove;
 }
 
 /*
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..c027b6c540 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,49 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE stats_regress_user1;
+CREATE ROLE stats_regress_user2;
+
+SET ROLE stats_regress_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE stats_regress_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (stats_regress_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'stats_regress_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE stats_regress_user1;
+DROP ROLE stats_regress_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..d091dcecd1 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns bigint</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> according to 
+      the specified userid, dbid and queryid. Returns the total number of
+      statement statistics that are reset based on the specified input.
+      If any of the parameter is not specified, the default value NULL(invalid)
+      is used and the statistics that match with other parameter(s) will be reset.
+      If no parameter is specified or specify everything as NULL(invalid), it will
+      discard all statistics.
+      By default, this function can only be executed by superusers. Access may
+      be granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.18.0.windows.1

From ea2109d5f9a8cb8249507a8c2c652cf82d03e2da Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Tue, 25 Sep 2018 11:20:19 +1000
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Based on the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.

Backward Compatible change, Now pg_stat_statements_reset() function
returns the number of statement entries that are reset.
---
 contrib/pg_stat_statements/Makefile           |   8 +-
 .../expected/pg_stat_statements.out           | 134 +++++++++++++++++-
 .../pg_stat_statements--1.6--1.7.sql          |  22 +++
 .../pg_stat_statements/pg_stat_statements.c   | 129 +++++++++++++----
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  45 ++++++
 doc/src/sgml/pgstatstatements.sgml            |  15 +-
 7 files changed, 309 insertions(+), 46 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..283c80b973 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -6,7 +6,7 @@ SET pg_stat_statements.track_utility = FALSE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "int";
@@ -122,7 +122,7 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       12
 (1 row)
 
 -- utility "create table" should not be shown
@@ -216,7 +216,7 @@ SET pg_stat_statements.track = 'none';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "one";
@@ -243,7 +243,7 @@ SET pg_stat_statements.track = 'top';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        2
 (1 row)
 
 DO LANGUAGE plpgsql $$
@@ -303,7 +303,7 @@ SET pg_stat_statements.track = 'all';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        7
 (1 row)
 
 -- we drop and recreate the functions to avoid any caching funnies
@@ -361,7 +361,7 @@ SET pg_stat_statements.track_utility = TRUE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        6
 (1 row)
 
 SELECT 1;
@@ -395,4 +395,126 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+                        0
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE regress_stats_user1                                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..619d4e8eaa
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS bigint
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79f54..61b166e597 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static long entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,7 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics according to userid, dbid, queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+	int64		num_remove;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	num_remove = entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_INT64(num_remove);
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
@@ -1302,7 +1337,9 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
 				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,52 +2266,82 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries according to parameters.
  */
-static void
-entry_reset(void)
+static long
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	/* If all parameter available, use the fast path */
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key out of hash if available */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
 	}
-
-	/*
-	 * Write new empty query file, perhaps even creating a new one to recover
-	 * if the file was missing.
-	 */
-	qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
-	if (qfile == NULL)
+	else
 	{
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not create file \"%s\": %m",
-						PGSS_TEXT_FILE)));
-		goto done;
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || (userid && entry->key.userid == userid)) &&
+				(!dbid || (dbid && entry->key.dbid == dbid)) &&
+				(!queryid || (queryid && entry->key.queryid == queryid)))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
 	}
 
-	/* If ftruncate fails, log it, but it's not a fatal problem */
-	if (ftruncate(fileno(qfile), 0) != 0)
-		ereport(LOG,
-				(errcode_for_file_access(),
-				 errmsg("could not truncate file \"%s\": %m",
-						PGSS_TEXT_FILE)));
+	if (num_entries == num_remove)
+	{
+		/*
+		 * Write new empty query file, perhaps even creating a new one to
+		 * recover if the file was missing.
+		 */
+		qfile = AllocateFile(PGSS_TEXT_FILE, PG_BINARY_W);
+		if (qfile == NULL)
+		{
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not create file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+			goto done;
+		}
 
-	FreeFile(qfile);
+		/* If ftruncate fails, log it, but it's not a fatal problem */
+		if (ftruncate(fileno(qfile), 0) != 0)
+			ereport(LOG,
+					(errcode_for_file_access(),
+					 errmsg("could not truncate file \"%s\": %m",
+							PGSS_TEXT_FILE)));
+
+		FreeFile(qfile);
 
 done:
-	pgss->extent = 0;
-	/* This counts as a query text garbage collection for our purposes */
-	record_gc_qtexts();
+		pgss->extent = 0;
+		/* This counts as a query text garbage collection for our purposes */
+		record_gc_qtexts();
+	}
 
 	LWLockRelease(pgss->lock);
+
+	return num_remove;
 }
 
 /*
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..fdd62a4834 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,49 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..d091dcecd1 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns bigint</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> according to 
+      the specified userid, dbid and queryid. Returns the total number of
+      statement statistics that are reset based on the specified input.
+      If any of the parameter is not specified, the default value NULL(invalid)
+      is used and the statistics that match with other parameter(s) will be reset.
+      If no parameter is specified or specify everything as NULL(invalid), it will
+      discard all statistics.
+      By default, this function can only be executed by superusers. Access may
+      be granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.18.0.windows.1

From 0ff234527371b3f7a8711b1d40bfe33741ee2df9 Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Tue, 25 Sep 2018 11:20:19 +1000
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Based on the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.

Backward Compatible change, Now pg_stat_statements_reset() function
returns the number of statement entries that are reset.
---
 contrib/pg_stat_statements/Makefile           |   8 +-
 .../expected/pg_stat_statements.out           | 148 +++++++++++++++++-
 .../pg_stat_statements--1.6--1.7.sql          |  22 +++
 .../pg_stat_statements/pg_stat_statements.c   |  90 +++++++++--
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  56 +++++++
 doc/src/sgml/pgstatstatements.sgml            |  16 +-
 7 files changed, 314 insertions(+), 28 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..f42e80b301 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -3,10 +3,24 @@ CREATE EXTENSION pg_stat_statements;
 -- simple and compound statements
 --
 SET pg_stat_statements.track_utility = FALSE;
+-- wrapper function to reset existing stats returns void
+CREATE FUNCTION pg_stat_statements_reset_wrapper() RETURNS void
+as
+$$
+SELECT pg_stat_statements_reset();
+$$
+LANGUAGE SQL;
+SELECT pg_stat_statements_reset_wrapper();
+ pg_stat_statements_reset_wrapper 
+----------------------------------
+ 
+(1 row)
+
+DROP FUNCTION pg_stat_statements_reset_wrapper();
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        1
 (1 row)
 
 SELECT 1 AS "int";
@@ -122,7 +136,7 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       12
 (1 row)
 
 -- utility "create table" should not be shown
@@ -216,7 +230,7 @@ SET pg_stat_statements.track = 'none';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "one";
@@ -243,7 +257,7 @@ SET pg_stat_statements.track = 'top';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        2
 (1 row)
 
 DO LANGUAGE plpgsql $$
@@ -303,7 +317,7 @@ SET pg_stat_statements.track = 'all';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        7
 (1 row)
 
 -- we drop and recreate the functions to avoid any caching funnies
@@ -361,7 +375,7 @@ SET pg_stat_statements.track_utility = TRUE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        6
 (1 row)
 
 SELECT 1;
@@ -395,4 +409,126 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+                        0
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE regress_stats_user1                                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..619d4e8eaa
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS bigint
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79f54..24523f68eb 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static long entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,33 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics according to userid, dbid, queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+	int64		num_remove;
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	num_remove = entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_INT64(num_remove);
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2256,57 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries according to parameters.
  */
-static void
-entry_reset(void)
+static long
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	/* If all parameter available, use the fast path */
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key out of hash if available */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else
+	{
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || (userid && entry->key.userid == userid)) &&
+				(!dbid || (dbid && entry->key.dbid == dbid)) &&
+				(!queryid || (queryid && entry->key.queryid == queryid)))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,7 +2335,10 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release:
 	LWLockRelease(pgss->lock);
+
+	return num_remove;
 }
 
 /*
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..6124a69df6 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -4,6 +4,17 @@ CREATE EXTENSION pg_stat_statements;
 -- simple and compound statements
 --
 SET pg_stat_statements.track_utility = FALSE;
+
+-- wrapper function to reset existing stats returns void
+CREATE FUNCTION pg_stat_statements_reset_wrapper() RETURNS void
+as
+$$
+SELECT pg_stat_statements_reset();
+$$
+LANGUAGE SQL;
+
+SELECT pg_stat_statements_reset_wrapper();
+DROP FUNCTION pg_stat_statements_reset_wrapper();
 SELECT pg_stat_statements_reset();
 
 SELECT 1 AS "int";
@@ -195,4 +206,49 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..4978a5931f 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns bigint</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,17 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> according to 
+      the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>. Returns the total number of
+      statement statistics that are reset based on the specified input.
+      If any of the parameter is not specified, the default value <literal>NULL</literal>(invalid)
+      is used and the statistics that match with other parameter(s) will be reset.
+      If no parameter is specified or specify everything as <literal>NULL</literal>(invalid),
+      it will discard all statistics.
+      By default, this function can only be executed by superusers. Access may
+      be granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.18.0.windows.1

From 1b49ca805bc4056b6f4373b1b84353e90c5b6073 Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Tue, 25 Sep 2018 11:20:19 +1000
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Based on the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.

Backward incompatible change, Now pg_stat_statements_reset() function
returns the number of statement entries that are reset.
---
 contrib/pg_stat_statements/Makefile           |   8 +-
 .../expected/pg_stat_statements.out           | 140 ++++++++++++++++--
 .../pg_stat_statements--1.6--1.7.sql          |  22 +++
 .../pg_stat_statements/pg_stat_statements.c   |  90 +++++++++--
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  48 +++++-
 doc/src/sgml/pgstatstatements.sgml            |  15 +-
 7 files changed, 293 insertions(+), 32 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..1a53f1cefb 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -3,9 +3,9 @@ CREATE EXTENSION pg_stat_statements;
 -- simple and compound statements
 --
 SET pg_stat_statements.track_utility = FALSE;
-SELECT pg_stat_statements_reset();
- pg_stat_statements_reset 
---------------------------
+SELECT NULL from pg_stat_statements_reset();
+ ?column? 
+----------
  
 (1 row)
 
@@ -108,7 +108,7 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT $1 AS "int"                                |     2 |    2
  SELECT $1 AS i UNION SELECT $2 ORDER BY i         |     1 |    2
  SELECT $1 || $2                                   |     1 |    1
- SELECT pg_stat_statements_reset()                 |     1 |    1
+ SELECT NULL from pg_stat_statements_reset()       |     1 |    1
  WITH t(f) AS (                                   +|     1 |    2
    VALUES ($1), ($2)                              +|       | 
  )                                                +|       | 
@@ -122,7 +122,7 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       12
 (1 row)
 
 -- utility "create table" should not be shown
@@ -216,7 +216,7 @@ SET pg_stat_statements.track = 'none';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                       10
 (1 row)
 
 SELECT 1 AS "one";
@@ -243,7 +243,7 @@ SET pg_stat_statements.track = 'top';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        2
 (1 row)
 
 DO LANGUAGE plpgsql $$
@@ -303,7 +303,7 @@ SET pg_stat_statements.track = 'all';
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        7
 (1 row)
 
 -- we drop and recreate the functions to avoid any caching funnies
@@ -361,7 +361,7 @@ SET pg_stat_statements.track_utility = TRUE;
 SELECT pg_stat_statements_reset();
  pg_stat_statements_reset 
 --------------------------
- 
+                        6
 (1 row)
 
 SELECT 1;
@@ -395,4 +395,126 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+                        0
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE regress_stats_user1                                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+                        2
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+                        9
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..619d4e8eaa
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS bigint
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79f54..24523f68eb 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static long entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,33 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics according to userid, dbid, queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+	int64		num_remove;
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	num_remove = entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_INT64(num_remove);
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2256,57 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries according to parameters.
  */
-static void
-entry_reset(void)
+static long
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	/* If all parameter available, use the fast path */
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key out of hash if available */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else
+	{
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || (userid && entry->key.userid == userid)) &&
+				(!dbid || (dbid && entry->key.dbid == dbid)) &&
+				(!queryid || (queryid && entry->key.queryid == queryid)))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,7 +2335,10 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release:
 	LWLockRelease(pgss->lock);
+
+	return num_remove;
 }
 
 /*
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..e7b0aa8a75 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -4,7 +4,8 @@ CREATE EXTENSION pg_stat_statements;
 -- simple and compound statements
 --
 SET pg_stat_statements.track_utility = FALSE;
-SELECT pg_stat_statements_reset();
+
+SELECT NULL from pg_stat_statements_reset();
 
 SELECT 1 AS "int";
 
@@ -195,4 +196,49 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..1bbc06bf34 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns bigint</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> according to 
+      the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>. Returns the total number of
+      statement statistics that are reset based on the specified input.
+      If any of the parameter is not specified, the default value <literal>NULL</literal>(invalid)
+      is used and the statistics that match with other parameter(s) will be reset.
+      If no parameter is specified or specify everything as <literal>NULL</literal>(invalid),
+      it will discard all statistics. By default, this function can only be executed by superusers.
+      Access may be granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.18.0.windows.1

From eeb2a225ae9a30e28445ecd2f62a7b046961e060 Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Tue, 13 Nov 2018 11:20:19 +1000
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Based on the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.
---
 contrib/pg_stat_statements/Makefile           |   8 +-
 .../expected/pg_stat_statements.out           | 122 ++++++++++++++++++
 .../pg_stat_statements--1.6--1.7.sql          |  22 ++++
 .../pg_stat_statements/pg_stat_statements.c   |  87 +++++++++++--
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  46 +++++++
 doc/src/sgml/pgstatstatements.sgml            |  14 +-
 7 files changed, 280 insertions(+), 21 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..9b8a1c8e81 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,126 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE regress_stats_user1                                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..c862de20a6
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79f54..0958cce12f 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics according to userid, dbid, queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,22 +2255,56 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries according to parameters.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	/* If all parameter available, use the fast path */
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key out of hash if available */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
 	}
+	else
+	{
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || (userid && entry->key.userid == userid)) &&
+				(!dbid || (dbid && entry->key.dbid == dbid)) &&
+				(!queryid || (queryid && entry->key.queryid == queryid)))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release;
 
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
@@ -2274,7 +2334,10 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release:
 	LWLockRelease(pgss->lock);
+
+	return;
 }
 
 /*
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..fcb1f52e0d 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +196,49 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..448858fa19 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,15 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> according to 
+      the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>. If any of the parameter is not specified,
+      the default value <literal>NULL</literal>(invalid) is used and the statistics
+      that match with other parameter(s) will be reset. If no parameter is specified or
+      specify everything as <literal>NULL</literal>(invalid), it will discard all statistics.
+      By default, this function can only be executed by superusers. Access may be granted
+      to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.18.0.windows.1

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..9b8a1c8e81 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,126 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE regress_stats_user1                                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..c862de20a6
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79f54..578e1571b6 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics corresponding to userid, dbid, and queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2255,68 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries corresponding to parameters passed.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
+	{
+		/* If all the parameters are available, use the fast path. */
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key if exists */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		/* Remove entries corresponding to valid parameters. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || entry->key.userid == userid) &&
+				(!dbid || entry->key.dbid == dbid) &&
+				(!queryid || entry->key.queryid == queryid))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+	else
+	{
+		/* Remove all entries. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+			num_remove++;
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release_lock;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,6 +2345,7 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release_lock:
 	LWLockRelease(pgss->lock);
 }
 
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..fdd62a4834 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,49 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..e9a9dafbf8 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> corresponding
+      to the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>.  If any of the parameters are not
+      specified, the default value <literal>NULL</literal>(invalid) is used for
+      each of them and the statistics that match with other parameters will be
+      reset.  If no parameter is specified or all the specified parameters are
+      <literal>NULL</literal>(invalid), it will discard all statistics.  By
+      default, this function can only be executed by superusers.  Access may be
+      granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>

From 14d806a9e0b5783d49965e308c1fcb2ac75c624b Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Thu, 15 Nov 2018 07:11:05 +1100
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Corresponding to the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.
---
 contrib/pg_stat_statements/Makefile           |   8 +-
 .../expected/pg_stat_statements.out           | 148 ++++++++++++++++++
 .../pg_stat_statements--1.6--1.7.sql          |  22 +++
 .../pg_stat_statements/pg_stat_statements.c   |  96 ++++++++++--
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  53 +++++++
 doc/src/sgml/pgstatstatements.sgml            |  15 +-
 7 files changed, 323 insertions(+), 21 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..40e2a4230a 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,152 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     1 |   10
+ SET ROLE regress_stats_user1                                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                              query                                               | calls | rows 
+--------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                  |     1 |    0
+ RESET ROLE                                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                                            |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3 |     1 |    2
+ SELECT pg_stat_statements_reset()                                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                   |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                     |     2 |   20
+ SET ROLE regress_stats_user2                                                                     |     1 |    0
+(9 rows)
+
+--
+-- remove query ('SELECT $1 + $2 AS "TWO"') executed by regress_stats_user2 in the current_database
+--
+SELECT pg_stat_statements_reset((SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+								(SELECT d.oid from pg_database As d where datname = current_database()),
+								(SELECT s.queryid FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"'));
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                                                  query                                                                   | calls | rows 
+------------------------------------------------------------------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                                                                          |     1 |    0
+ CREATE ROLE regress_stats_user2                                                                                                          |     1 |    0
+ RESET ROLE                                                                                                                               |     2 |    0
+ SELECT pg_stat_statements_reset($1,$2,s.queryid) FROM pg_stat_statements AS s WHERE s.query = $3                                         |     1 |    2
+ SELECT pg_stat_statements_reset((SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                                                 +|     1 |    1
+                                                                 (SELECT d.oid from pg_database As d where datname = current_database()),+|       | 
+                                                                 (SELECT s.queryid FROM pg_stat_statements AS s WHERE s.query = $2))      |       | 
+ SELECT pg_stat_statements_reset()                                                                                                        |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = $1                                                           |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"                                                             |     3 |   29
+(8 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..c862de20a6
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79f54..578e1571b6 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics corresponding to userid, dbid, and queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2255,68 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries corresponding to parameters passed.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
+	{
+		/* If all the parameters are available, use the fast path. */
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key if exists */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		/* Remove entries corresponding to valid parameters. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || entry->key.userid == userid) &&
+				(!dbid || entry->key.dbid == dbid) &&
+				(!queryid || entry->key.queryid == queryid))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+	else
+	{
+		/* Remove all entries. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+			num_remove++;
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release_lock;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,6 +2345,7 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release_lock:
 	LWLockRelease(pgss->lock);
 }
 
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..d981c69a96 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,57 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid) FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid) FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 + $2 AS "TWO"') executed by regress_stats_user2 in the current_database
+--
+SELECT pg_stat_statements_reset((SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+								(SELECT d.oid from pg_database As d where datname = current_database()),
+								(SELECT s.queryid FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"'));
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..e9a9dafbf8 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> corresponding
+      to the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>.  If any of the parameters are not
+      specified, the default value <literal>NULL</literal>(invalid) is used for
+      each of them and the statistics that match with other parameters will be
+      reset.  If no parameter is specified or all the specified parameters are
+      <literal>NULL</literal>(invalid), it will discard all statistics.  By
+      default, this function can only be executed by superusers.  Access may be
+      granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.18.0.windows.1

From 0c63d999056164045b73ba29f2def64743c9ccba Mon Sep 17 00:00:00 2001
From: Hari Babu <kommi.haribabu@gmail.com>
Date: Thu, 15 Nov 2018 07:11:05 +1100
Subject: [PATCH] pg_stat_statements_reset to reset specific query/user/db
 statistics

Now the pg_stat_statements_reset() can accept input parameters of
userid, dbid and queryid. Corresponding to the specified input values,
specific statistics entries are released. The new behaviour is useful
to get the fresh new statistics of a specific query/user/database
to observation without resetting all the existing statistics.
If no parameters are passed, it will release all entries as per the
old behaviour.
---
 contrib/pg_stat_statements/Makefile           |   8 +-
 .../expected/pg_stat_statements.out           | 168 ++++++++++++++++++
 .../pg_stat_statements--1.6--1.7.sql          |  22 +++
 .../pg_stat_statements/pg_stat_statements.c   |  96 ++++++++--
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  58 ++++++
 doc/src/sgml/pgstatstatements.sgml            |  15 +-
 7 files changed, 348 insertions(+), 21 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..401002d674 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,172 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     1 |   10
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(11 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"' LIMIT 1;
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    1
+         FROM pg_stat_statements AS s WHERE s.query = $3 LIMIT $4                 |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     2 |   21
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    1
+         FROM pg_stat_statements AS s WHERE s.query = $3 LIMIT $4                 |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid)                                          +|     1 |    1
+                 FROM pg_roles AS r WHERE r.rolname = $1                          |       | 
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     3 |   31
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..c862de20a6
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79f54..578e1571b6 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics corresponding to userid, dbid, and queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2255,68 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries corresponding to parameters passed.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
+	{
+		/* If all the parameters are available, use the fast path. */
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key if exists */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		/* Remove entries corresponding to valid parameters. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || entry->key.userid == userid) &&
+				(!dbid || entry->key.dbid == dbid) &&
+				(!queryid || entry->key.queryid == queryid))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+	else
+	{
+		/* Remove all entries. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+			num_remove++;
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release_lock;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,6 +2345,7 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release_lock:
 	LWLockRelease(pgss->lock);
 }
 
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..1bed08428c 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,62 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"' LIMIT 1;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..e9a9dafbf8 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> corresponding
+      to the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>.  If any of the parameters are not
+      specified, the default value <literal>NULL</literal>(invalid) is used for
+      each of them and the statistics that match with other parameters will be
+      reset.  If no parameter is specified or all the specified parameters are
+      <literal>NULL</literal>(invalid), it will discard all statistics.  By
+      default, this function can only be executed by superusers.  Access may be
+      granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.18.0.windows.1

From 7ddf072df3f66dc1c81cc87704f18370132f9bad Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Sat, 17 Nov 2018 08:52:12 +0530
Subject: [PATCH] Extend pg_stat_statements_reset to reset statistics specific
 to a particular user/db/query.

The function pg_stat_statements_reset() is extended to accept userid, dbid,
and queryid as input parameters.  Now, it can discard the statistics
gathered so far by pg_stat_statements corresponding to the specified
userid, dbid, and queryid.  If no parameter is specified or all the
specified parameters are NULL, it will discard all statistics as per the
old behavior.

The new behavior is useful to get the fresh statistics for a specific
user/database/query without resetting all the existing statistics.

Author: Haribabu Kommi, with few additional changes by me
Reviewed-by: Michael Paquier, Amit Kapila and Fujii Masao
Discussion: https://postgr.es/m/CAJrrPGcyh-gkFswyc6C661K6cknL0XkNqVT0sQt2mFNMR4HRKA@mail.gmail.com
---
 contrib/pg_stat_statements/Makefile                |   8 +-
 .../expected/pg_stat_statements.out                | 169 +++++++++++++++++++++
 .../pg_stat_statements--1.6--1.7.sql               |  22 +++
 contrib/pg_stat_statements/pg_stat_statements.c    |  96 ++++++++++--
 .../pg_stat_statements/pg_stat_statements.control  |   2 +-
 .../pg_stat_statements/sql/pg_stat_statements.sql  |  58 +++++++
 doc/src/sgml/pgstatstatements.sgml                 |  15 +-
 7 files changed, 349 insertions(+), 21 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a5038..051ce46 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c35..e0571b7 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,173 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     1 |   10
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(11 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     2 |   21
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(10 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid)                                          +|     1 |    1
+                 FROM pg_roles AS r WHERE r.rolname = $1                          |       | 
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     3 |   31
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(9 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ SELECT pg_stat_statements_reset() |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000..c862de2
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT NULL,
+	IN dbid Oid DEFAULT NULL,
+	IN queryid bigint DEFAULT NULL
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79..578e157 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics corresponding to userid, dbid, and queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_ARGISNULL(0) ? 0 : PG_GETARG_OID(0);
+	dbid = PG_ARGISNULL(1) ? 0 : PG_GETARG_OID(1);
+	queryid = (uint64) (PG_ARGISNULL(2) ? 0 : PG_GETARG_INT64(2));
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2255,68 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries corresponding to parameters passed.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
+	{
+		/* If all the parameters are available, use the fast path. */
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key if exists */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		/* Remove entries corresponding to valid parameters. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || entry->key.userid == userid) &&
+				(!dbid || entry->key.dbid == dbid) &&
+				(!queryid || entry->key.queryid == queryid))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+	else
+	{
+		/* Remove all entries. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+			num_remove++;
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release_lock;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,6 +2345,7 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release_lock:
 	LWLockRelease(pgss->lock);
 }
 
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b..14cb422 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd..4190da1 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,62 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(NULL,NULL,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset();
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed..e9a9daf 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> corresponding
+      to the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>.  If any of the parameters are not
+      specified, the default value <literal>NULL</literal>(invalid) is used for
+      each of them and the statistics that match with other parameters will be
+      reset.  If no parameter is specified or all the specified parameters are
+      <literal>NULL</literal>(invalid), it will discard all statistics.  By
+      default, this function can only be executed by superusers.  Access may be
+      granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
1.8.3.1

From fbf14f4d5bd30a180f7203837e3787b12ca5196e Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Sat, 17 Nov 2018 08:52:12 +0530
Subject: [PATCH] Extend pg_stat_statements_reset to reset statistics specific
 to a particular user/db/query.

The function pg_stat_statements_reset() is extended to accept userid, dbid,
and queryid as input parameters.  Now, it can discard the statistics
gathered so far by pg_stat_statements corresponding to the specified
userid, dbid, and queryid.  If no parameter is specified or all the
specified parameters are NULL, it will discard all statistics as per the
old behavior.

The new behavior is useful to get the fresh statistics for a specific
user/database/query without resetting all the existing statistics.

Author: Haribabu Kommi, with few additional changes by me
Reviewed-by: Michael Paquier, Amit Kapila and Fujii Masao
Discussion: https://postgr.es/m/CAJrrPGcyh-gkFswyc6C661K6cknL0XkNqVT0sQt2mFNMR4HRKA@mail.gmail.com
---
 contrib/pg_stat_statements/Makefile           |   8 +-
 .../expected/pg_stat_statements.out           | 198 ++++++++++++++++++
 .../pg_stat_statements--1.6--1.7.sql          |  22 ++
 .../pg_stat_statements/pg_stat_statements.c   |  96 +++++++--
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  64 ++++++
 doc/src/sgml/pgstatstatements.sgml            |  15 +-
 7 files changed, 384 insertions(+), 21 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..c759763be2 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,202 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                    query                                     | calls | rows 
+------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                              |     1 |    0
+ CREATE ROLE regress_stats_user2                                              |     1 |    0
+ RESET ROLE                                                                   |     2 |    0
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT pg_stat_statements_reset($1)                                          |     1 |    1
+ SELECT pg_stat_statements_reset()                                            |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C" |     1 |   10
+ SET ROLE regress_stats_user1                                                 |     1 |    0
+ SET ROLE regress_stats_user2                                                 |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     2 |   22
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     3 |   34
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(11 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid)                                          +|     1 |    1
+                 FROM pg_roles AS r WHERE r.rolname = $1                          |       | 
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     4 |   45
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(10 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                 query                  | calls | rows 
+----------------------------------------+-------+------
+ SELECT pg_stat_statements_reset(0,0,0) |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..6fc3fed4c9
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT 0,
+	IN dbid Oid DEFAULT 0,
+	IN queryid bigint DEFAULT 0
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 33f9a79f54..dcb2a919a7 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics corresponding to userid, dbid, and queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_GETARG_OID(0);
+	dbid = PG_GETARG_OID(1);
+	queryid = (uint64) PG_GETARG_INT64(2);
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2255,68 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries corresponding to parameters passed.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
+	{
+		/* If all the parameters are available, use the fast path. */
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key if exists */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		/* Remove entries corresponding to valid parameters. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || entry->key.userid == userid) &&
+				(!dbid || entry->key.dbid == dbid) &&
+				(!queryid || entry->key.queryid == queryid))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+	else
+	{
+		/* Remove all entries. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+			num_remove++;
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release_lock;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,6 +2345,7 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release_lock:
 	LWLockRelease(pgss->lock);
 }
 
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..aef890d893 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,68 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..e69fa7ec91 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> corresponding
+      to the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>.  If any of the parameters are not
+      specified, the default value <literal>0</literal>(invalid) is used for
+      each of them and the statistics that match with other parameters will be
+      reset.  If no parameter is specified or all the specified parameters are
+      <literal>0</literal>(invalid), it will discard all statistics.  By
+      default, this function can only be executed by superusers.  Access may be
+      granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
-- 
2.18.0.windows.1

From c171057ff079d5888801747d49918fedb1874db7 Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Sat, 17 Nov 2018 08:52:12 +0530
Subject: [PATCH] Extend pg_stat_statements_reset to reset statistics specific
 to a particular user/db/query.

The function pg_stat_statements_reset() is extended to accept userid, dbid,
and queryid as input parameters.  Now, it can discard the statistics
gathered so far by pg_stat_statements corresponding to the specified
userid, dbid, and queryid.  If no parameter is specified or all the
specified parameters are NULL, it will discard all statistics as per the
old behavior.

The new behavior is useful to get the fresh statistics for a specific
user/database/query without resetting all the existing statistics.

Author: Haribabu Kommi, with few additional changes by me
Reviewed-by: Michael Paquier, Amit Kapila and Fujii Masao
Discussion: https://postgr.es/m/CAJrrPGcyh-gkFswyc6C661K6cknL0XkNqVT0sQt2mFNMR4HRKA@mail.gmail.com
---
 contrib/pg_stat_statements/Makefile           |   8 +-
 .../expected/pg_stat_statements.out           | 198 ++++++++++++++++++
 .../pg_stat_statements--1.6--1.7.sql          |  22 ++
 .../pg_stat_statements/pg_stat_statements.c   |  96 +++++++--
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  64 ++++++
 doc/src/sgml/pgstatstatements.sgml            | 106 +++++++---
 7 files changed, 455 insertions(+), 41 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..c759763be2 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,202 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                    query                                     | calls | rows 
+------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                              |     1 |    0
+ CREATE ROLE regress_stats_user2                                              |     1 |    0
+ RESET ROLE                                                                   |     2 |    0
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT pg_stat_statements_reset($1)                                          |     1 |    1
+ SELECT pg_stat_statements_reset()                                            |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C" |     1 |   10
+ SET ROLE regress_stats_user1                                                 |     1 |    0
+ SET ROLE regress_stats_user2                                                 |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     2 |   22
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     3 |   34
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(11 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid)                                          +|     1 |    1
+                 FROM pg_roles AS r WHERE r.rolname = $1                          |       | 
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     4 |   45
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(10 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                 query                  | calls | rows 
+----------------------------------------+-------+------
+ SELECT pg_stat_statements_reset(0,0,0) |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..6fc3fed4c9
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT 0,
+	IN dbid Oid DEFAULT 0,
+	IN queryid bigint DEFAULT 0
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 9131991b83..f177ebaa2c 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics corresponding to userid, dbid, and queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_GETARG_OID(0);
+	dbid = PG_GETARG_OID(1);
+	queryid = (uint64) PG_GETARG_INT64(2);
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2255,68 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries corresponding to parameters passed.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
+	{
+		/* If all the parameters are available, use the fast path. */
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key if exists */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		/* Remove entries corresponding to valid parameters. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || entry->key.userid == userid) &&
+				(!dbid || entry->key.dbid == dbid) &&
+				(!queryid || entry->key.queryid == queryid))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+	else
+	{
+		/* Remove all entries. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+			num_remove++;
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release_lock;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,6 +2345,7 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release_lock:
 	LWLockRelease(pgss->lock);
 }
 
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..aef890d893 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,68 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..e519207266 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> corresponding
+      to the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>.  If any of the parameters are not
+      specified, the default value <literal>0</literal>(invalid) is used for
+      each of them and the statistics that match with other parameters will be
+      reset.  If no parameter is specified or all the specified parameters are
+      <literal>0</literal>(invalid), it will discard all statistics.  By
+      default, this function can only be executed by superusers.  Access may be
+      granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
@@ -494,36 +501,87 @@ bench=# \x
 bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
                nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
           FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
--[ RECORD 1 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2;
+-[ RECORD 1 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2
 calls       | 3000
-total_time  | 9609.00100000002
-rows        | 2836
-hit_percent | 99.9778970000200936
--[ RECORD 2 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2;
+total_time  | 25565.855387
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 2 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2
 calls       | 3000
-total_time  | 8015.156
-rows        | 2990
-hit_percent | 99.9731126579631345
--[ RECORD 3 ]---------------------------------------------------------------------
+total_time  | 20756.669379
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 3 ]--------------------------------------------------------------------
 query       | copy pgbench_accounts from stdin
 calls       | 1
-total_time  | 310.624
+total_time  | 291.865911
 rows        | 100000
-hit_percent | 0.30395136778115501520
--[ RECORD 4 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2;
+hit_percent | 100.0000000000000000
+-[ RECORD 4 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
 calls       | 3000
-total_time  | 271.741999999997
+total_time  | 271.232977
 rows        | 3000
-hit_percent | 93.7968855088209426
--[ RECORD 5 ]---------------------------------------------------------------------
+hit_percent | 98.5723926698852723
+-[ RECORD 5 ]--------------------------------------------------------------------
 query       | alter table pgbench_accounts add primary key (aid)
 calls       | 1
-total_time  | 81.42
+total_time  | 160.588563
 rows        | 0
-hit_percent | 34.4947735191637631
+hit_percent | 100.0000000000000000
+
+
+bench=# SELECT pg_stat_statements_reset(0,0,s.queryid) FROM pg_stat_statements AS s
+bench-# WHERE s.query = 'UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2';
+
+bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
+               nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
+          FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
+-[ RECORD 1 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2
+calls       | 3000
+total_time  | 20756.669379
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 2 ]--------------------------------------------------------------------
+query       | copy pgbench_accounts from stdin
+calls       | 1
+total_time  | 291.865911
+rows        | 100000
+hit_percent | 100.0000000000000000
+-[ RECORD 3 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
+calls       | 3000
+total_time  | 271.232977
+rows        | 3000
+hit_percent | 98.5723926698852723
+-[ RECORD 4 ]--------------------------------------------------------------------
+query       | alter table pgbench_accounts add primary key (aid)
+calls       | 1
+total_time  | 160.588563
+rows        | 0
+hit_percent | 100.0000000000000000
+-[ RECORD 5 ]--------------------------------------------------------------------
+query       | vacuum analyze pgbench_accounts
+calls       | 1
+total_time  | 136.448116
+rows        | 0
+hit_percent | 99.9201915403032721
+
+bench=# SELECT pg_stat_statements_reset(0,0,0);
+
+bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
+               nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
+          FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
+-[ RECORD 1 ]---------------------------------------
+query       | SELECT pg_stat_statements_reset(0,0,0)
+calls       | 1
+total_time  | 0.189497
+rows        | 1
+hit_percent | 
+
 </screen>
  </sect2>
 
-- 
2.18.0.windows.1

From a9c60c7dc68698edb832308279ca6cfcc4908230 Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Sat, 17 Nov 2018 08:52:12 +0530
Subject: [PATCH] Extend pg_stat_statements_reset to reset statistics specific
 to a particular user/db/query.

The function pg_stat_statements_reset() is extended to accept userid, dbid,
and queryid as input parameters.  Now, it can discard the statistics
gathered so far by pg_stat_statements corresponding to the specified
userid, dbid, and queryid.  If no parameter is specified or all the
specified parameters are NULL, it will discard all statistics as per the
old behavior.

The new behavior is useful to get the fresh statistics for a specific
user/database/query without resetting all the existing statistics.

Author: Haribabu Kommi, with few additional changes by me
Reviewed-by: Michael Paquier, Amit Kapila and Fujii Masao
Discussion: https://postgr.es/m/CAJrrPGcyh-gkFswyc6C661K6cknL0XkNqVT0sQt2mFNMR4HRKA@mail.gmail.com
---
 contrib/pg_stat_statements/Makefile           |   8 +-
 .../expected/pg_stat_statements.out           | 198 ++++++++++++++++++
 .../pg_stat_statements--1.6--1.7.sql          |  22 ++
 .../pg_stat_statements/pg_stat_statements.c   |  96 +++++++--
 .../pg_stat_statements.control                |   2 +-
 .../sql/pg_stat_statements.sql                |  64 ++++++
 doc/src/sgml/pgstatstatements.sgml            | 106 +++++++---
 7 files changed, 455 insertions(+), 41 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a50380dc..051ce46f0c 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c3550c..c759763be2 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,202 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                    query                                     | calls | rows 
+------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                              |     1 |    0
+ CREATE ROLE regress_stats_user2                                              |     1 |    0
+ RESET ROLE                                                                   |     2 |    0
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT pg_stat_statements_reset($1)                                          |     1 |    1
+ SELECT pg_stat_statements_reset()                                            |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C" |     1 |   10
+ SET ROLE regress_stats_user1                                                 |     1 |    0
+ SET ROLE regress_stats_user2                                                 |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     2 |   22
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     3 |   34
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(11 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid)                                          +|     1 |    1
+                 FROM pg_roles AS r WHERE r.rolname = $1                          |       | 
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     4 |   45
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(10 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                 query                  | calls | rows 
+----------------------------------------+-------+------
+ SELECT pg_stat_statements_reset(0,0,0) |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000000..6fc3fed4c9
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT 0,
+	IN dbid Oid DEFAULT 0,
+	IN queryid bigint DEFAULT 0
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 9131991b83..f177ebaa2c 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics corresponding to userid, dbid, and queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_GETARG_OID(0);
+	dbid = PG_GETARG_OID(1);
+	queryid = (uint64) PG_GETARG_INT64(2);
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2255,68 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries corresponding to parameters passed.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
+	{
+		/* If all the parameters are available, use the fast path. */
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key if exists */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		/* Remove entries corresponding to valid parameters. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || entry->key.userid == userid) &&
+				(!dbid || entry->key.dbid == dbid) &&
+				(!queryid || entry->key.queryid == queryid))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+	else
+	{
+		/* Remove all entries. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+			num_remove++;
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release_lock;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,6 +2345,7 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release_lock:
 	LWLockRelease(pgss->lock);
 }
 
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b4c0..14cb422354 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd1bf..aef890d893 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,68 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed485..26bb82da4a 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> corresponding
+      to the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>.  If any of the parameters are not
+      specified, the default value <literal>0</literal>(invalid) is used for
+      each of them and the statistics that match with other parameters will be
+      reset.  If no parameter is specified or all the specified parameters are
+      <literal>0</literal>(invalid), it will discard all statistics.  By
+      default, this function can only be executed by superusers.  Access may be
+      granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
@@ -494,36 +501,87 @@ bench=# \x
 bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
                nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
           FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
--[ RECORD 1 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2;
+-[ RECORD 1 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2
 calls       | 3000
-total_time  | 9609.00100000002
-rows        | 2836
-hit_percent | 99.9778970000200936
--[ RECORD 2 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2;
+total_time  | 25565.855387
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 2 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2
 calls       | 3000
-total_time  | 8015.156
-rows        | 2990
-hit_percent | 99.9731126579631345
--[ RECORD 3 ]---------------------------------------------------------------------
+total_time  | 20756.669379
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 3 ]--------------------------------------------------------------------
 query       | copy pgbench_accounts from stdin
 calls       | 1
-total_time  | 310.624
+total_time  | 291.865911
 rows        | 100000
-hit_percent | 0.30395136778115501520
--[ RECORD 4 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2;
+hit_percent | 100.0000000000000000
+-[ RECORD 4 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
 calls       | 3000
-total_time  | 271.741999999997
+total_time  | 271.232977
 rows        | 3000
-hit_percent | 93.7968855088209426
--[ RECORD 5 ]---------------------------------------------------------------------
+hit_percent | 98.5723926698852723
+-[ RECORD 5 ]--------------------------------------------------------------------
 query       | alter table pgbench_accounts add primary key (aid)
 calls       | 1
-total_time  | 81.42
+total_time  | 160.588563
 rows        | 0
-hit_percent | 34.4947735191637631
+hit_percent | 100.0000000000000000
+
+
+bench=# SELECT pg_stat_statements_reset(0,0,s.queryid) FROM pg_stat_statements AS s
+            WHERE s.query = 'UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2';
+
+bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
+               nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
+          FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
+-[ RECORD 1 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2
+calls       | 3000
+total_time  | 20756.669379
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 2 ]--------------------------------------------------------------------
+query       | copy pgbench_accounts from stdin
+calls       | 1
+total_time  | 291.865911
+rows        | 100000
+hit_percent | 100.0000000000000000
+-[ RECORD 3 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
+calls       | 3000
+total_time  | 271.232977
+rows        | 3000
+hit_percent | 98.5723926698852723
+-[ RECORD 4 ]--------------------------------------------------------------------
+query       | alter table pgbench_accounts add primary key (aid)
+calls       | 1
+total_time  | 160.588563
+rows        | 0
+hit_percent | 100.0000000000000000
+-[ RECORD 5 ]--------------------------------------------------------------------
+query       | vacuum analyze pgbench_accounts
+calls       | 1
+total_time  | 136.448116
+rows        | 0
+hit_percent | 99.9201915403032721
+
+bench=# SELECT pg_stat_statements_reset(0,0,0);
+
+bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
+               nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
+          FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
+-[ RECORD 1 ]---------------------------------------
+query       | SELECT pg_stat_statements_reset(0,0,0)
+calls       | 1
+total_time  | 0.189497
+rows        | 1
+hit_percent | 
+
 </screen>
  </sect2>
 
-- 
2.18.0.windows.1

From 2541f89e16199bc6b777698d1e13a690be616534 Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Thu, 10 Jan 2019 08:22:59 +0530
Subject: [PATCH] Extend pg_stat_statements_reset to reset statistics specific
 to a particular user/db/query.

The function pg_stat_statements_reset() is extended to accept userid, dbid,
and queryid as input parameters.  Now, it can discard the statistics
gathered so far by pg_stat_statements corresponding to the specified
userid, dbid, and queryid.  If no parameter is specified or all the
specified parameters have default value aka 0, it will discard all
statistics as per the old behavior.

The new behavior is useful to get the fresh statistics for a specific
user/database/query without resetting all the existing statistics.

Author: Haribabu Kommi, with few additional changes by me
Reviewed-by: Michael Paquier, Amit Kapila and Fujii Masao
Discussion: https://postgr.es/m/CAJrrPGcyh-gkFswyc6C661K6cknL0XkNqVT0sQt2mFNMR4HRKA@mail.gmail.com
---
 contrib/pg_stat_statements/Makefile                |   8 +-
 .../expected/pg_stat_statements.out                | 198 +++++++++++++++++++++
 .../pg_stat_statements--1.6--1.7.sql               |  22 +++
 contrib/pg_stat_statements/pg_stat_statements.c    |  96 ++++++++--
 .../pg_stat_statements/pg_stat_statements.control  |   2 +-
 .../pg_stat_statements/sql/pg_stat_statements.sql  |  64 +++++++
 doc/src/sgml/pgstatstatements.sgml                 | 106 ++++++++---
 7 files changed, 455 insertions(+), 41 deletions(-)
 create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile
index 14a5038..051ce46 100644
--- a/contrib/pg_stat_statements/Makefile
+++ b/contrib/pg_stat_statements/Makefile
@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 
diff --git a/contrib/pg_stat_statements/expected/pg_stat_statements.out b/contrib/pg_stat_statements/expected/pg_stat_statements.out
index 5318c35..c759763 100644
--- a/contrib/pg_stat_statements/expected/pg_stat_statements.out
+++ b/contrib/pg_stat_statements/expected/pg_stat_statements.out
@@ -395,4 +395,202 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                    query                                     | calls | rows 
+------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                              |     1 |    0
+ CREATE ROLE regress_stats_user2                                              |     1 |    0
+ RESET ROLE                                                                   |     2 |    0
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT pg_stat_statements_reset($1)                                          |     1 |    1
+ SELECT pg_stat_statements_reset()                                            |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C" |     1 |   10
+ SET ROLE regress_stats_user1                                                 |     1 |    0
+ SET ROLE regress_stats_user2                                                 |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     2 |   22
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     3 |   34
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(11 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid)                                          +|     1 |    1
+                 FROM pg_roles AS r WHERE r.rolname = $1                          |       | 
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     4 |   45
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(10 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                 query                  | calls | rows 
+----------------------------------------+-------+------
+ SELECT pg_stat_statements_reset(0,0,0) |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;
diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
new file mode 100644
index 0000000..6fc3fed
--- /dev/null
+++ b/contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql
@@ -0,0 +1,22 @@
+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT 0,
+	IN dbid Oid DEFAULT 0,
+	IN queryid bigint DEFAULT 0
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 9131991..f177eba 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics corresponding to userid, dbid, and queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_GETARG_OID(0);
+	dbid = PG_GETARG_OID(1);
+	queryid = (uint64) PG_GETARG_INT64(2);
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2255,68 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries corresponding to parameters passed.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
+	{
+		/* If all the parameters are available, use the fast path. */
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key if exists */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		/* Remove entries corresponding to valid parameters. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || entry->key.userid == userid) &&
+				(!dbid || entry->key.dbid == dbid) &&
+				(!queryid || entry->key.queryid == queryid))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+	else
+	{
+		/* Remove all entries. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+			num_remove++;
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release_lock;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,6 +2345,7 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release_lock:
 	LWLockRelease(pgss->lock);
 }
 
diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control
index 617038b..14cb422 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.control
+++ b/contrib/pg_stat_statements/pg_stat_statements.control
@@ -1,5 +1,5 @@
 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true
diff --git a/contrib/pg_stat_statements/sql/pg_stat_statements.sql b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
index a8361fd..aef890d 100644
--- a/contrib/pg_stat_statements/sql/pg_stat_statements.sql
+++ b/contrib/pg_stat_statements/sql/pg_stat_statements.sql
@@ -195,4 +195,68 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;
diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml
index c0217ed..26bb82d 100644
--- a/doc/src/sgml/pgstatstatements.sgml
+++ b/doc/src/sgml/pgstatstatements.sgml
@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> corresponding
+      to the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>.  If any of the parameters are not
+      specified, the default value <literal>0</literal>(invalid) is used for
+      each of them and the statistics that match with other parameters will be
+      reset.  If no parameter is specified or all the specified parameters are
+      <literal>0</literal>(invalid), it will discard all statistics.  By
+      default, this function can only be executed by superusers.  Access may be
+      granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
@@ -494,36 +501,87 @@ bench=# \x
 bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
                nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
           FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
--[ RECORD 1 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2;
+-[ RECORD 1 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2
 calls       | 3000
-total_time  | 9609.00100000002
-rows        | 2836
-hit_percent | 99.9778970000200936
--[ RECORD 2 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2;
+total_time  | 25565.855387
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 2 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2
 calls       | 3000
-total_time  | 8015.156
-rows        | 2990
-hit_percent | 99.9731126579631345
--[ RECORD 3 ]---------------------------------------------------------------------
+total_time  | 20756.669379
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 3 ]--------------------------------------------------------------------
 query       | copy pgbench_accounts from stdin
 calls       | 1
-total_time  | 310.624
+total_time  | 291.865911
 rows        | 100000
-hit_percent | 0.30395136778115501520
--[ RECORD 4 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2;
+hit_percent | 100.0000000000000000
+-[ RECORD 4 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
 calls       | 3000
-total_time  | 271.741999999997
+total_time  | 271.232977
 rows        | 3000
-hit_percent | 93.7968855088209426
--[ RECORD 5 ]---------------------------------------------------------------------
+hit_percent | 98.5723926698852723
+-[ RECORD 5 ]--------------------------------------------------------------------
 query       | alter table pgbench_accounts add primary key (aid)
 calls       | 1
-total_time  | 81.42
+total_time  | 160.588563
 rows        | 0
-hit_percent | 34.4947735191637631
+hit_percent | 100.0000000000000000
+
+
+bench=# SELECT pg_stat_statements_reset(0,0,s.queryid) FROM pg_stat_statements AS s
+            WHERE s.query = 'UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2';
+
+bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
+               nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
+          FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
+-[ RECORD 1 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2
+calls       | 3000
+total_time  | 20756.669379
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 2 ]--------------------------------------------------------------------
+query       | copy pgbench_accounts from stdin
+calls       | 1
+total_time  | 291.865911
+rows        | 100000
+hit_percent | 100.0000000000000000
+-[ RECORD 3 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
+calls       | 3000
+total_time  | 271.232977
+rows        | 3000
+hit_percent | 98.5723926698852723
+-[ RECORD 4 ]--------------------------------------------------------------------
+query       | alter table pgbench_accounts add primary key (aid)
+calls       | 1
+total_time  | 160.588563
+rows        | 0
+hit_percent | 100.0000000000000000
+-[ RECORD 5 ]--------------------------------------------------------------------
+query       | vacuum analyze pgbench_accounts
+calls       | 1
+total_time  | 136.448116
+rows        | 0
+hit_percent | 99.9201915403032721
+
+bench=# SELECT pg_stat_statements_reset(0,0,0);
+
+bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
+               nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
+          FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
+-[ RECORD 1 ]---------------------------------------
+query       | SELECT pg_stat_statements_reset(0,0,0)
+calls       | 1
+total_time  | 0.189497
+rows        | 1
+hit_percent | 
+
 </screen>
  </sect2>
 
-- 
1.8.3.1