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Re: Query puts 7.3.4 on endless loop but 7.4beta5 is fine. [ with better indenting ]

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Rajesh Kumar Mallah <mallah(at)trade-india(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Query puts 7.3.4 on endless loop but 7.4beta5 is fine. [ with better indenting ]
Date: 2003-10-30 16:11:12
Message-ID: 28551.1067530272@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Rajesh Kumar Mallah <mallah(at)trade-india(dot)com> writes:
> SELECT DISTINCT main.* FROM
> (
>    (
>       (
>          (
>             Tickets main  JOIN Groups as Groups_1  ON ( main.id = Groups_1.Instance)
>          )  JOIN
>          Principals as Principals_2  ON ( Groups_1.id = Principals_2.ObjectId)
>       ) JOIN
>       CachedGroupMembers as CachedGroupMembers_3  ON ( Principals_2.id = CachedGroupMembers_3.GroupId)
>    )  JOIN
>    Users as Users_4  ON ( CachedGroupMembers_3.MemberId = Users_4.id)
> )   WHERE
>  ...

I think the reason for the performance difference is that 7.3 treats
JOIN syntax as forcing a particular join order, while 7.4 doesn't.

			regards, tom lane

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