Re: Not Picking Index

"Gauri Kanekar" <meetgaurikanekar@gmail.com> writes:
> I want the planner to ignore a specific index.
> I am testing some query output. For that purpose i dont want the index.
> I that possible to ignore a index by the planner.

    begin;
    drop index soandso;
    explain analyze ...;
    rollback;

Note the DROP INDEX will acquire exclusive lock on the table, so this
might not be the greatest thing to do in a production environment.
In PG 8.2 and up there is a sneakier way to do it that won't acquire
any more lock than the statement-under-test does:

    begin;
    update pg_index set indisvalid = false
      where indexrelid = 'soandso'::regclass;
    explain analyze ...;
    rollback;

            regards, tom lane