From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Waldemar Bergstreiser <littlesuspense(at)web(dot)de> |
Cc: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: |
Date: | 2009-06-30 14:26:43 |
Message-ID: | 17347.1246372003@sss.pgh.pa.us |
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Lists: | pgsql-general |
Waldemar Bergstreiser <littlesuspense(at)web(dot)de> writes:
> Just try to rewrite query below with left outter joins. I had not found any compact syntax.
> select * from a, outer( b, outer c), outer (d, outer f )
> where a.b_id = b.id and b.c_id = c.id and a.d_id = d.id and d.f_id = f.id;
This has got pretty much the same problem as Oracle's syntax: there's no
principled way to decide what it *means*. Which join is each of the
WHERE conditions supposed to be attached to, and why? What do you do if
you want a behavior slightly different from whatever the engine decides
it means?
The standard's syntax is a bit more verbose, but at least it's perfectly
clear which conditions are outer-join conditions and which are filters.
regards, tom lane
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