FW: Index usage

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От BBI Edwin Punzalan
Тема FW: Index usage
Дата
Msg-id 001401c4d1f2$1df5df00$b400a8c0@bluebamboo.ph
обсуждение исходный текст
Список pgsql-performance
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.


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