Re: Moving pg_xlog - Mailing list pgsql-performance

From Himanshu Baweja
Subject Re: Moving pg_xlog
Date
Msg-id 20050602144721.15002.qmail@web51004.mail.yahoo.com
Whole thread Raw
In response to Re: Moving pg_xlog  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance
Tom Lane <tgl@sss.pgh.pa.us> wrote:
>It seems highly unlikely that putting more stuff on the xlog disk will
>improve performance --- at least not if your bottleneck is update speed.
 
Tom you are right.. i did some testing...
1) default config--- xlog on disk1 and data on disk2=>
    27 mins and 22 secs
2) xlog and some tables on disk1 and rest of tables on disk2=>
    28 mins and 38 secs
 
but the most startling of the results is....
3) xlog on disk1 and half the tables on partition 1 of disk2 and other half on partition 2 of disk2
   24 mins and 14 secs
 
 ??????????
shouldnt moving data to diff partitions degrade performance instead of enhancing it....
 
also  in configuration 1, my heap_blks_hit/heap_blks_fetched was good enough....
but in configuration 3, its was really low.. something of the order of 1/15...
still the performance improved....
 
any ideas.....
does moving across partitions help...
 
Regards
Himanshu
 

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