> 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;
this really smacks of that four-letter word that starts with h... -- i
am glad we have finally come around on the subject :-) 
seriously, this is a great technique and an enormous time saver during
query optimization. thanks for sharing!
george