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Re: Order-by and indexes - Mailing list pgsql-novice

From Tom Lane
Subject Re: Order-by and indexes
Date
Msg-id 6005.1309360004@sss.pgh.pa.us
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In response to Order-by and indexes  (Odd Hogstad <odd.hogstad@smartm.no>)
List pgsql-novice
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Odd Hogstad <odd.hogstad@smartm.no> writes:
> I need to get the latest entry of a large table matching a certain criteria.
> This is my query:

> SELECT * FROM "data" WHERE "data"."fk" = 238496 ORDER BY "data"."id" DESC
> LIMIT 1

A two-column index on (fk, id) would help for this.  If you think about
the ordering of the index entries you'll see why.

            regards, tom lane

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