From: dev@kbsolutions.ch
To: pgsql-sql@postgresql.org
Subject: update from select
Date: Mon, 29 Oct 2007 10:18:38 +0100
Message-ID: <0d5e01c81a0c$b0f67250$1601a8c0@kbsc1> (raw)
Hello
I have a performance problem with an SQL statement.
Is there a better way to do this update:
UPDATE table1 SET column2 = temp_table.column2, column3 =
temp_table.column3, column4 = CAST(temp_table.column4 AS date) FROM
(
SELECT DISTINCT
table2.column1,
table2.column2,
table2.column3,
table2.column4
FROM table2 WHERE column4 IS NOT NULL AND column4 <> '' AND
(length(column4) = 10 OR length(column4) = 23)
) AS temp_table
WHERE table1.column1 = temp_table.column1;
The select by it's own takes around 1 second. The Update is around 120'000
rows. I got an index on column1. The whole query needs around 16 minutes.
The same procedure on MSSQL needs around 30 seconds. I hope to get it too in
Postgres.
Please help me.
Regards
Reto
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To: pgsql-sql@postgresql.org
Cc: dev@kbsolutions.ch
Subject: Re: update from select
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