pg_xlog size

From: Tech Madhu <technimadhu(at)gmail(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: pg_xlog size
Date: 2011-03-15 15:09:19
Message-ID: AANLkTik6ud2NrbLoLYCOkKW0eFva5n4LKeTYX93i+Dqt@mail.gmail.com
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hi all,

Setup:
Sparc, Solaris 10, Postgres 9.0.2, using streaming replication and hot
standby. 1 master 1 slave

Everything works fine (w.r.t replication), but the pg_xlog size grows
continuously, though i had no operations going on. Also the archiving to the
other side filled up the other side FS.
ls -l /var/postgres/data/pg_xlog | wc -l
103
At start, there were only 15 files. The max_wal_segments is 32, but not sure
why iam seeing 103 files. Also the archiving dir size doubled (w.r.t number
of files archived). and filled up the filesystem.
I manually logged into postgres and run checkpoint; did not see any file
reduction

Pasting some of the relevant conf values
The checkpoint_segments is commented out, so default to 3 segments right?

postgresql.conf
-----------------------
wal_level = hot_standby
checkpoint_warning = 30s
#checkpoint_segments = 3 # in logfile segments, min 1, 16MB
each
#checkpoint_timeout = 5min # range 30s-1h
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 -
1.0

archive_mode = on # allows archiving to be done
# (change requires restart)
archive_command = 'cp %p /var/postgres/walfiles/%f' # this dir
is NFS mounted dir on the slave node
archive_timeout = 30

max_wal_senders = 5
wal_keep_segments = 32

hot_standby = on

track_counts = on
autovacuum = on

-----------------------------------------
I want to ensure it only keeps up to certain number of files, not keep on
growing and filling up my filesystem and requiring manual intervention.
Appreciate any tips or pointers to documentation. Thanks in advance. I
looked in the archives, but one user had this problem because he had the
wal_keep_segments set to 300 (whereas i have it only at 32)

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