Re: Increase checkpoint segments ?

["Tomeh, Husam" <htomeh(at)firstam(dot)com>]

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

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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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