Re: Tsearch2 Initial Search Speed - Mailing list pgsql-performance

From Howard Cole
Subject Re: Tsearch2 Initial Search Speed
Date
Msg-id 485789C1.3000803@selestial.com
Whole thread Raw
In response to Re: Tsearch2 Initial Search Speed  (Alan Hodgson <ahodgson@simkin.ca>)
Responses Re: Tsearch2 Initial Search Speed  (Howard Cole <howardnews@selestial.com>)
Re: Tsearch2 Initial Search Speed  (Matthew Wakeling <matthew@flymine.org>)
List 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.

pgsql-performance by date:

Previous
From: Chris Mair
Date:
Subject: Re: [pgsql-performance] function difference(geometry,geometry) is SLOW!
Next
From: Howard Cole
Date:
Subject: Re: Tsearch2 Initial Search Speed