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Re: Q on views and performance

From: "Dean Gibson (DB Administrator)" <postgresql(at)ultimeth(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Q on views and performance
Date: 2008-02-23 16:55:42
Message-ID: 47C0500E.90907@ultimeth.com (view raw or flat)
Thread:
Lists: pgsql-performance
On 2008-02-23 08:49, Dean Gibson (DB Administrator) wrote:
> Why 10,000 views???  What's wrong with the ONE view above?  You DON'T 
> want to be defining VIEWs based on actual tables VALUES;  leave that 
> to the SELECT.  For that matter, what's wrong with the final SELECT I 
> listed (below)?
>
> SELECT a1.word AS word1, a2.word AS word2
>   FROM S JOIN T a1 USING( word )
>     LEFT JOIN T a2 USING( zipk )
>   WHERE a1.type = <int1> AND a2.type = <int2>;
>
> -- Dean
Amendment:  I forgot, that if it's a LEFT JOIN you have to write it as:

SELECT a1.word AS word1, a2.word AS word2
  FROM S JOIN T a1 USING( word )
    LEFT JOIN T a2 USING( zipk )
  WHERE a1.type = <int1> AND (a2.type = <int2> OR a2.type IS NULL);

-- Dean

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