Re: Tsearch2 Initial Search Speed

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От Howard Cole
Тема Re: Tsearch2 Initial Search Speed
Дата
Msg-id 485789C1.3000803@selestial.com
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Ответ на Re: Tsearch2 Initial Search Speed  (Alan Hodgson <ahodgson@simkin.ca>)
Ответы Re: Tsearch2 Initial Search Speed  (Howard Cole <howardnews@selestial.com>)
Re: Tsearch2 Initial Search Speed  (Matthew Wakeling <matthew@flymine.org>)
Список 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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