From: Richard Neill <rn214@richardneill.org>
To: PostgreSQL Performance <pgsql-performance@postgresql.org>
Subject: Re: Why does the query planner use two full indexes, when a dedicated partial index exists?
Date: Thu, 27 Dec 2012 16:43:38 +0000
Message-ID: <50DC7ABA.5010109@richardneill.org> (raw)
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On 27/12/12 16:17, Jeff Janes wrote:
>
> I still think your best bet is to get rid of the partial index and trade
> the full one on (parcel_id_code) for one on (parcel_id_code,exit_state).
> I think that will be much less fragile than reindexing in a cron job.
>
So, at the moment, I have 3 indexes:
full: parcel_id_code
full: exit_state
full: parcel_id_code where exit state is null
Am I right that when you suggest just a single, joint index
(parcel_id_code,exit_state)
instead of all 3 of the others,
it will allow me to optimally run all of the following? :
1. SELECT * from tbl_tracker WHERE parcel_id_code=22345 AND exit_state
IS NULL
(this is the one we've been discussing)
2. SELECT * from tbl_tracker where parcel_id_code=44533
3. SELECT * from tbl_tracker where exit_code = 2
(2 and 3 are examples of queries I need to run for other purposes,
unrelated to this thread, but which use the other indexes.).
Thanks,
Richard
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To: pgsql-performance@postgresql.org
Cc: rn214@richardneill.org
Subject: Re: Why does the query planner use two full indexes, when a dedicated partial index exists?
In-Reply-To: <50DC7ABA.5010109@richardneill.org>
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