Message-ID: <43CADB5C.3020302@ultimeth.com>
Date: Sun, 15 Jan 2006 15:31:40 -0800
From: "Dean Gibson (DB Administrator)" <postgresql4@ultimeth.com>
Organization: UltiMeth Systems
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To: pgsql-sql <pgsql-sql@postgresql.org>
Subject: Re: What does "merge-joinable join conditions" mean ????
References: <43CAAFA6.6050001@ultimeth.com>
	<20060115215448.GA30809@winnie.fuhr.org>
	<43CACC78.7090107@ultimeth.com> <24299.1137367313@sss.pgh.pa.us>
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On 2006-01-15 15:21, Tom Lane wrote:
> Really?  The FULL JOIN condition using ~ is the source of the failure, and I'd be quite surprised if changing WHERE makes it work.
>   

Works fine:

EXPLAIN SELECT count(*)  FROM "Extra" FULL JOIN  "GeoRestrict" ON
callsign ~ pattern  WHERE geo_region =
4;
                                   QUERY
PLAN
---------------------------------------------------------------------------------
Aggregate  (cost=1934.02..1934.02 rows=1 width=0)
   ->  Nested Loop Left Join  (cost=1.18..1926.66 rows=2943 width=0)
         Join Filter: ("outer".callsign ~ ("inner".pattern)::text)
         ->  Seq Scan on "Extra"  (cost=0.00..866.00 rows=2943 width=10)
               Filter: (geo_region = 4)
         ->  Materialize  (cost=1.18..1.34 rows=16 width=7)
               ->  Seq Scan on "GeoRestrict"  (cost=0.00..1.16 rows=16
width=7)

Note that this used to be just a LEFT JOIN (which also worked), but
today I wanted to include rows from "GeoRestrict" that had nulls for the
left-hand-side of the query, so I changed the LEFT JOIN to a FULL JOIN
(that worked), and then attempted to add a condition to restrict which
rows were included from "GeoRestrict", and that gave the error.

-- Dean