Re: performance versus order of fields in row

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От Jan Wieck
Тема Re: performance versus order of fields in row
Дата
Msg-id 3FC4249C.8050406@Yahoo.com
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Ответ на Re: performance versus order of fields in row  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: performance versus order of fields in row  (Tom Lane <tgl@sss.pgh.pa.us>)
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Tom Lane wrote:

>"D. Stimits" <stimits@comcast.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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