Postgres Pro
Downloads
Home   >   mailing lists

Re: big select is resulting in a large amount of disk writing by kjournald - Mailing list pgsql-performance

From Joseph S
Subject Re: big select is resulting in a large amount of disk writing by kjournald
Date
Msg-id hfp2jf$1kdm$1@news.hub.org
Whole thread Raw
In response to Re: big select is resulting in a large amount of disk writing by kjournald  (Greg Smith <greg@2ndquadrant.com>)
Responses Re: big select is resulting in a large amount of disk writing by kjournald
List pgsql-performance
Tree view 
Greg Smith wrote:
> Joseph S wrote:
>> So I run "select count(*) from large_table" and I see in xosview a
>> solid block of write activity. Runtime is 28125.644 ms for the first
>> run.  The second run does not show a block of write activity and takes
>> 3327.441 ms
> http://wiki.postgresql.org/wiki/Hint_Bits
>

Hmm. A large select results in a lot of writes? This seems broken.  And
if we are setting these hint bits then what do we need VACUUM for?  Is
there any way to tune this behavior? Is there any way to get stats on
how many rows/pages would need hint bits set?

pgsql-performance by date:

Previous
From: Greg Smith
Date:
Subject: Re: big select is resulting in a large amount of disk writing by kjournald
Next
From: Greg Smith
Date:
Subject: Re: big select is resulting in a large amount of disk writing by kjournald