Re: Increase checkpoint segments ?

Typically in this scenario, more and larger WAL segments can help speed
up your updates. However, the default size of a WAL segment is 16MB
which can be set at postgresql compile time, and can not be changed
thereafter. So, you'd need to increase the checkpoint_segments
parameters to speed up your updates. Increasing the WAL buffers which
are memory pages allocated in the shared memory for WAL data won't help.

Sincerely,

--
Husam
________________________________

From: pgsql-admin-owner(at)postgresql(dot)org
[mailto:pgsql-admin-owner(at)postgresql(dot)org] On Behalf Of Abu Mushayeed
Sent: Tuesday, December 12, 2006 9:17 AM
To: pgsql-admin(at)postgresql(dot)org
Subject: [ADMIN] Increase checkpoint segments ?

Hello,

I have many updates happening in the DB. All of them works with millions
of rows. When this happens I get the following message:

checkpoints are occurring too frequently (294 seconds apart)
Consider increasing the configuration parameter "checkpoint_segments".

Some values from my postgresql.conf files are as follows. My question is
do I really increase the checkpoint segments or should I increase the
WAL buffers or do an create table as and then insert instead of update
statement?

shared_buffers = 20000 #60000 # min 16 or
max_connections*2, 8KB each -- Bizgres work_mem = 65536 #131072 #65536
# min 64, size in KB -- Bizgres Database change from 1024 to 65536
maintenance_work_mem = 524288 #131072 # min 1024, size in KB
max_fsm_pages = 8000000 # min max_fsm_relations*16, 6
bytes each
max_fsm_relations = 32768 # min 100, ~70 bytes each

fsync = on # turns forced synchronization
on or off
wal_buffers = 128 # min 4, 8KB each
checkpoint_segments = 256 # in logfile segments, min 1,
16MB each
checkpoint_timeout = 3600 #300 # range 30-3600, in seconds
checkpoint_warning = 300 # in seconds, 0 is off
default_statistics_target = 250 # range 1-1000

Thanks
Abu

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