| From: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
|---|---|
| To: | Caio Casimiro <casimiro(dot)listas(at)gmail(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Slow index scan on B-Tree index over timestamp field |
| Date: | 2013-11-04 18:56:01 |
| Message-ID: | 1383591361.34516.YahooMailNeo@web162902.mail.bf1.yahoo.com |
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| Lists: | pgsql-performance |
Caio Casimiro <casimiro(dot)listas(at)gmail(dot)com> wrote:
> I have one query running at ~ 7 seconds and I would like to know
> if it's possible to make it run faster, once this query runs lots
> of time in my experiment.
> Buffers: shared hit=2390 read=32778
> Total runtime: 24066.145 ms
> effective_cache_size = 2GB
> it seems the problem is with the 'tweet' table.
The EXPLAIN ANALYZE output shows it taking 24 seconds, 8.9 seconds
of which is in accessing the tweet_topic table and 15.1 seconds in
accessing the tweet table. It looks like you have a painfully low
cache hit ratio. The plan looks reasonable to me; it looks like
you need more RAM to cache data if you want better speed.
--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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