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Re: update query taking too long

From: "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: update query taking too long
Date: 2007-06-28 06:28:26
Message-ID: 20070628062826.GC22066@a-kretschmer.de (view raw or flat)
Thread:
Lists: pgsql-performance
am  Thu, dem 28.06.2007, um 16:16:50 +1000 mailte Chris folgendes:
> Is there a better way to write the update? I thought about something 
> like this (but couldn't get it working - guess I don't have the right 
> syntax):
> 
> update t1 set domainname=(select id, SUBSTRING(emailaddress FROM 
> POSITION('@' IN emailaddress)) from table t2) AS t2 where t1.id=t2.id

test=# select * from foo;
 id |    mail     | domain
----+-------------+--------
  1 | foo(at)foo(dot)tld |
  2 | bar(at)bar(dot)tld |
(2 rows)

test=*# update foo set domain=SUBSTRING(mail FROM (POSITION('@' IN
mail)+1));
UPDATE 2
test=*# select * from foo;
 id |    mail     | domain
----+-------------+---------
  1 | foo(at)foo(dot)tld | foo.tld
  2 | bar(at)bar(dot)tld | bar.tld
(2 rows)


(without the @ in the domain...)


Andreas
-- 
Andreas Kretschmer
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