From: | Zeljko Trogrlic <zeljko(at)technologist(dot)com> |
---|---|
To: | zlatko(at)iskon(dot)hr |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Indexes not working (bug in 7.0.2?) |
Date: | 2000-09-05 08:41:03 |
Message-ID: | 4.1.20000905103858.00a108c0@pop.tel.hr |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
Manual says you should use it after initial data entry, after entering a
large amount of rows and periodically.
At 23:02 4.9.2000 , Zlatko Calusic wrote:
>Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>
>> Zlatko Calusic <zlatko(at)iskon(dot)hr> writes:
>> > It is now NOT using the index, and I don't understand why? Queries are
>> > practically the same, tables are practically the same, why is postgres
>> > using indexes in the first case and not in the second?
>>
>> Because it has substantially different ideas about the sizes of the
>> two tables --- notice the different estimated row counts. If you
>> haven't "vacuum analyzed" these tables recently, do so to bring the
>> planner's statistics up-to-date, and then see what you get. You may
>> also care to read the user's manual chapter about EXPLAIN,
>> http://www.postgresql.org/users-lounge/docs/7.0/postgres/c4888.htm
>>
>
>Yes, thanks to all who helped. 'vacuum analyze' was the magical
>incantation that helped.
>
>I still have one uncertainty. Is it possible that after some time
>postgres once again decides not to use indices (assuming I haven't run
>'vacuum analyze' again)?
>
>--
>Zlatko
From | Date | Subject | |
---|---|---|---|
Next Message | Zeljko Trogrlic | 2000-09-05 08:53:03 | Re: Change to DatabaseMetaData.java for the jdbc2 driver (fwd) |
Previous Message | Hoosain Madhi | 2000-09-05 08:26:43 | VACUUM Error |