| From: | Howard Cole <howardnews(at)selestial(dot)com> |
|---|---|
| To: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Tsearch2 Initial Search Speed |
| Date: | 2008-06-17 09:54:09 |
| Message-ID: | 485789C1.3000803@selestial.com |
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| Lists: | pgsql-performance |
Alan Hodgson wrote:
> It's because everything is cached, in particular the relevant rows from
> the "email" table (accessing which took 22 of the original 27 seconds).
>
> The plan looks good for what it's doing.
>
> I don't see that query getting much faster unless you could add a lot more
> cache RAM; 30K random IOs off disk is going to take a fair bit of time
> regardless of what you do.
>
>
Thanks Alan, I guessed that the caching was the difference, but I do not
understand why there is a heap scan on the email table? The query seems
to use the email_fts_index correctly, which only takes 6 seconds, why
does it then need to scan the email table?
Sorry If I sound a bit stupid - I am not very experienced with the
analyse statement.
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