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Re: Tsearch2 Initial Search Speed

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: (view raw, whole thread or download thread mbox)
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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