"Wang Mike" <itlist@msn.com> writes:
> but this query: select * from test_uuid where id =
> 'df2b10aa-a31d-11d7-9867-0050babb6029'::uuid dosn't use index
> QUERY PLAN
> ---------------------------------------------------------------
> Seq Scan on test_uuid (cost=0.00..22.50 rows=500 width=140)
> Filter: (id = 'df2b10aa-a31d-11d7-9867-0050babb6029'::uuid)
> why ??
The rows estimate looks pretty fishy --- I think you are getting the
0.5 default selectivity estimate for an operator that has no restriction
estimator. Most likely you should have created the operator using eqsel
and eqjoinsel as the restriction/join estimators.
regards, tom lane