Re: Estimation problem with a LIKE clause containing a / - Mailing list pgsql-performance

Tom,

On Nov 8, 2007 12:14 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I've applied a patch that might help you:
> http://archives.postgresql.org/pgsql-committers/2007-11/msg00104.php

AFAICS, it doesn't seem to fix the problem. I just compiled
REL8_1_STABLE branch and I still has the following behaviour:
lbo=# ANALYZE cms_items;
ANALYZE
lbo=# explain analyze select * from cms_items where ancestors LIKE '1062/%';
                                                 QUERY PLAN
------------------------------------------------------------------------------------------------------------
 Seq Scan on cms_items  (cost=0.00..688.26 rows=1 width=103) (actual
time=0.009..22.258 rows=11326 loops=1)
   Filter: ((ancestors)::text ~~ '1062/%'::text)
 Total runtime: 29.835 ms
(3 rows)

lbo=# show lc_collate;
 lc_collate
-------------
 fr_FR.UTF-8
(1 row)

Do you see any reason why your patch doesn't change anything in this case?

Thanks.

--
Guillaume