Re: Why Does UPDATE Take So Long?
От | Andreas Kretschmer |
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Тема | Re: Why Does UPDATE Take So Long? |
Дата | |
Msg-id | 20080930192052.GA8842@tux обсуждение исходный текст |
Ответ на | Why Does UPDATE Take So Long? (Bill Thoen <bthoen@gisnet.com>) |
Список | pgsql-general |
Bill Thoen <bthoen@gisnet.com> schrieb: > Working with PG 8.1 I'm trying to update a char(4) column, and it's > taking a very long time; 15 minutes so far and no end in sight. From the > explain, it doesn't seem like it should take that long, and this column > is not indexed. Sure, there's 2.7 million records but it only takes a > few minutes to scan the whole file. Is there some special overhead I > should be aware of with an UPDATE? I VACUUMed and ANALYZEd first, too. > > Or am I just expecting too much? > > Here's the explain: > explain UPDATE farms SET prog_year='2007'; > QUERY PLAN > ---------------------------------------------------------------- > Seq Scan on farms (cost=0.00..59144.07 rows=2772207 width=54) > (1 row) Please provide us an EXPLAIN ANALYSE. But without a WHERE-condition a seq-scan are logical, and PG has to rewrite the whole table and the transaction-log. Andreas -- Really, I'm not out to destroy Microsoft. That will just be a completely unintentional side effect. (Linus Torvalds) "If I was god, I would recompile penguin with --enable-fly." (unknown) Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889°
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