BUG #6719: PG shouldn't filter on same criteria as index search

The following bug has been logged on the website:

Bug reference: 6719
Logged by: BLove
Email address: blove319(at)hotmail(dot)com
PostgreSQL version: 9.1.3
Operating system: Centos 5
Description:

After doing an equality search on an indexed field, PG is doing a filter on
the same value using a regex. That appears to be a useless operation that
will only consume cpu cycles.

explain select * from transactions.subscriber_504700_txns_y2012m05 lh where
lh.account_code LIKE '34016975\_DAT\_FR\_HF';
QUERY PLAN

----------------------------------------------------------------------------------------------------------------------------------------------
Index Scan using idx_subscriber_504700_txns_y2012m05_account_code on
subscriber_504700_txns_y2012m05 lh (cost=0.00..17.02 rows=3 width=131)
Index Cond: (account_code = '34016975_DAT_FR_HF'::text)
Filter: (account_code ~~ '34016975\_DAT\_FR\_HF'::text)