Re: [HACKERS] a problem with index and user define type

[Weiping He]

Tom Lane wrote:

"Wang Mike" <[EMAIL PROTECTED]> 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



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