Re: a problem with index and user define type

Tom Lane wrote:

>"Wang Mike" <itlist(at)msn(dot)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
>
>
>
Hi, Tom,

I'm trying to test it, but don't know if I understood you correctly,
you mean we should try to create the operator using
eqsel/eqjoinsel estimators, right?
But after we added those estimators like this:

CREATE OPERATOR = (
LEFTARG = uuid,
RIGHTARG = uuid,
COMMUTATOR = =,
NEGATOR = <>,
PROCEDURE = uuid_eq,
RESTRICT = eqsel,
JOIN = eqjoinsel
);

the situation trun worse: now the explain shows the query using the
index,
the we can't select out the match row! Any hint about what's wrong
with us?

Thanks and Reagards

Laser