Hello It's not bug. a LIKE 'some%' is different operation than a = str_const.
if you don't use C locale, then you have to use varchar_pattern_ops. please try: create index like_index on tab(str varchar_pattern_ops); don't forget do ANALYZE tab before Regards Pavel Stehule On 19/12/2007, dhliu <[EMAIL PROTECTED]> wrote: > db =# explain SELECT seq FROM tab WHERE str like 'edt%'; > QUERY PLAN > ----------------------------------------------------------- > Seq Scan on tab (cost=0.00..6465.55 rows=1 width=4) > Filter: (str ~~ 'edt%'::text) > (2 rows) > > db=# explain SELECT seq FROM tab WHERE str = 'edta'; > QUERY PLAN > ------------------------------------------------------------------------------ > Index Scan using tab_pkey on tab (cost=0.00..8.30 rows=1 width=4) > Index Cond: (str = 'edta'::text) > (2 rows) > > > > PostgreSQL 8.2.5 on i586-mandriva-linux-gnu, compiled by GCC > i586-mandriva-linux-gnu-gcc (GCC) 4.2.2 20070909 (prerelease) > (4.2.2-0.RC.1mdv2008.0) > > > Thank you. > > > Edward Liu > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Have you searched our list archives? > > http://archives.postgresql.org > ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
