From: | Jan Wieck <JanWieck(at)Yahoo(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | stimits(at)comcast(dot)net, pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: performance versus order of fields in row |
Date: | 2003-11-26 03:57:16 |
Message-ID: | 3FC4249C.8050406@Yahoo.com |
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Lists: | pgsql-general |
Tom Lane wrote:
>"D. Stimits" <stimits(at)comcast(dot)net> writes:
>
>
>>I'm not looking for an exact answer here, but instead something more
>>"rule of thumb". If I have a table with many fields, and I retrieving
>>small groups of fields during a SELECT, whereby the groups of fields are
>>indexed and/or clustered, will I get a faster select in the left-most
>>fields, or the right-most fields? Or will it not matter?
>>
>>
>
>Fields earlier in the table definition (further to the left) are
>marginally faster to access than ones further to the right. I doubt it
>would be real noticeable unless you had hundreds of fields altogether.
>
Do we still "cache" field offsets for not-nullable-fixed-size columns?
Jan
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