From a0f5954af19ddcfea946b15744f2006a789dc4bd Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Sun, 15 Mar 2015 17:37:07 +0100
Subject: [PATCH] Increase max_wal_size's default from 128MB to 1GB.
The introduction of min_wal_size & max_wal_size in 88e982302684 makes it
feasible to increase the default upper bound in checkpoint
size. Previously raising the default would lead to a increased disk
footprint, even if more segments weren't beneficial. The low default of
checkpoint size is one of common performance problem users have thus
increasing the default makes sense. Setups where the increase in
maximum disk usage is a problem will very likely have to run with a
modified configuration anyway.
Discussion: 54F4EFB8.40202@agliodbs.com,
CA+TgmoZEAgX5oMGJOHVj8L7XOkAe05Gnf45rP40m-K3FhZRVKg@mail.gmail.com
Author: Josh Berkus, after a discussion involving lots of people.
---
doc/src/sgml/config.sgml | 2 +-
doc/src/sgml/wal.sgml | 2 +-
src/backend/access/transam/xlog.c | 2 +-
src/backend/utils/misc/guc.c | 2 +-
src/backend/utils/misc/postgresql.conf.sample | 2 +-
5 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index d0f43c64af3..b30c68dc138 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2430,7 +2430,7 @@ include_dir 'conf.d'
checkpoints. This is a soft limit; WAL size can exceed
<varname>max_wal_size</> under special circumstances, like
under heavy load, a failing <varname>archive_command</>, or a high
- <varname>wal_keep_segments</> setting. The default is 128 MB.
+ <varname>wal_keep_segments</> setting. The default is 1 GB.
Increasing this parameter can increase the amount of time needed for
crash recovery.
This parameter can only be set in the <filename>postgresql.conf</>
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index b57749fdbc3..f4083c3fe57 100644
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -475,7 +475,7 @@
linkend="guc-checkpoint-timeout"> seconds, or if
<xref linkend="guc-max-wal-size"> is about to be exceeded,
whichever comes first.
- The default settings are 5 minutes and 128 MB, respectively.
+ The default settings are 5 minutes and 1 GB, respectively.
If no WAL has been written since the previous checkpoint, new checkpoints
will be skipped even if <varname>checkpoint_timeout</> has passed.
(If WAL archiving is being used and you want to put a lower limit on how
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 17bd5d85a95..72af2c43303 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -79,7 +79,7 @@ extern uint32 bootstrap_data_checksum_version;
/* User-settable parameters */
-int max_wal_size = 8; /* 128 MB */
+int max_wal_size = 64; /* 1 GB */
int min_wal_size = 5; /* 80 MB */
int wal_keep_segments = 0;
int XLOGbuffers = -1;
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 7196b0b2157..26275bda129 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2191,7 +2191,7 @@ static struct config_int ConfigureNamesInt[] =
GUC_UNIT_XSEGS
},
&max_wal_size,
- 8, 2, INT_MAX,
+ 64, 2, INT_MAX,
NULL, assign_max_wal_size, NULL
},
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index d7a61f1fc4b..110983f1764 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -199,7 +199,7 @@
# - Checkpoints -
#checkpoint_timeout = 5min # range 30s-1h
-#max_wal_size = 128MB # in logfile segments
+#max_wal_size = 1GB
#min_wal_size = 80MB
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_warning = 30s # 0 disables
--
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