From 367205d51ef471defd0f9df76840dee1c4cd4036 Mon Sep 17 00:00:00 2001 From: Kyotaro Horiguchi Date: Tue, 28 Feb 2017 11:39:48 +0900 Subject: [PATCH] Add WAL releaf vent for replication slots Adds a capability to limit the number of segments kept by replication slots by a GUC variable. --- src/backend/access/transam/xlog.c | 12 ++++++++++++ src/backend/utils/misc/guc.c | 10 ++++++++++ src/backend/utils/misc/postgresql.conf.sample | 1 + src/include/access/xlog.h | 1 + 4 files changed, 24 insertions(+) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 5016273..6c57e99 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -104,6 +104,7 @@ int wal_level = WAL_LEVEL_MINIMAL; int CommitDelay = 0; /* precommit delay in microseconds */ int CommitSiblings = 5; /* # concurrent xacts needed to sleep */ int wal_retrieve_retry_interval = 5000; +int max_slot_wal_keep_segments = 0; #ifdef WAL_DEBUG bool XLOG_DEBUG = false; @@ -9267,6 +9268,17 @@ KeepLogSeg(XLogRecPtr recptr, XLogSegNo *logSegNo) XLByteToSeg(keep, slotSegNo); + /* emergency vent */ + if (max_slot_wal_keep_segments > 0 && + slotSegNo < segno - max_slot_wal_keep_segments) + { + ereport(WARNING, + (errmsg ("restart LSN of replication slots is ignored by checkpoint"), + errdetail("Some replication slots lose required WAL segnents to continue."))); + /* slotSegNo cannot be negative here */ + slotSegNo = segno - max_slot_wal_keep_segments; + } + if (slotSegNo <= 0) segno = 1; else if (slotSegNo < segno) diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 0707f66..4ff1c2a 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -2335,6 +2335,16 @@ static struct config_int ConfigureNamesInt[] = }, { + {"max_slot_wal_keep_segments", PGC_SIGHUP, REPLICATION_SENDING, + gettext_noop("Sets the maximum keep segments by replication slots."), + NULL + }, + &max_slot_wal_keep_segments, + 0, 0, INT_MAX, + NULL, NULL, NULL + }, + + { {"wal_sender_timeout", PGC_SIGHUP, REPLICATION_SENDING, gettext_noop("Sets the maximum time to wait for WAL replication."), NULL, diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index 157d775..7424a63 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -233,6 +233,7 @@ #max_wal_senders = 10 # max number of walsender processes # (change requires restart) #wal_keep_segments = 0 # in logfile segments, 16MB each; 0 disables +#max_slot_wal_keep_segments = 0 # in logfile segments, 16MB each; 0 disables #wal_sender_timeout = 60s # in milliseconds; 0 disables #max_replication_slots = 10 # max number of replication slots diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 9f036c7..fae1b87 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -97,6 +97,7 @@ extern bool reachedConsistency; extern int min_wal_size; extern int max_wal_size; extern int wal_keep_segments; +extern int max_slot_wal_keep_segments; extern int XLOGbuffers; extern int XLogArchiveTimeout; extern int wal_retrieve_retry_interval; -- 2.9.2