From: Dmitry Tkach <dmitry@openratings.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-sql <pgsql-sql@postgresql.org>
Subject: Re: Trouble with explicit joins
Date: Thu, 21 Oct 2004 19:36:41 -0400
Message-ID: <41784809.4070009@openratings.com> (raw)
In-Reply-To: <12900.1098401533@sss.pgh.pa.us>
References: <41783BC7.4040207@openratings.com>
<12900.1098401533@sss.pgh.pa.us>
Tom Lane wrote:
>Dmitry Tkach <dmitry@openratings.com> writes:
>
>
>>I suppose, this is because the planner takes the order, in which the
>>tables appear in the explicit joins as some kind of a hint to how I want
>>that query to be executed,
>>
>>
>
>It's not a "hint", it's a requirement. In general, changing the order
>in which outer joins are executed changes the results.
>
>There are some cases in which it is safe to rearrange the order, but
>determining this takes close analysis of the join conditions, and we
>don't (yet) have any code to do that. So the planner must be
>conservative and take your join order as gospel.
>
> regards, tom lane
>
>
Yeah.. that's what I figured.
Are you saying there is no way around it at all? Isn't there a syntax
supported to write a left join with implicit joins?
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To: pgsql-sql@postgresql.org
Cc: dmitry@openratings.com, tgl@sss.pgh.pa.us
Subject: Re: Trouble with explicit joins
In-Reply-To: <41784809.4070009@openratings.com>
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