FW: Index usage

Hi everyone,

Can anyone please explain postgres' behavior on our index.

I did the following query tests on our database:

====================
db=# create index chatlogs_date_idx on chatlogs (date);
CREATE
db=# explain select date from chatlogs where date>='11/23/04';
NOTICE: QUERY PLAN:

Index Scan using chatlogs_date_idx on chatlogs (cost=0.00..144.11 rows=36
width=4)

EXPLAIN
db=# explain select date from chatlogs where date>='10/23/04';
NOTICE: QUERY PLAN:

Seq Scan on chatlogs (cost=0.00..23938.06 rows=253442 width=4)

EXPLAIN====================

Date's datatype is date. Its just odd that I just change the actual date of
search and the index is not being used anymore.