Re: Order-by and indexes

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