Re: Help with slow table update
| От | Igor Neyman |
|---|---|
| Тема | Re: Help with slow table update |
| Дата | |
| Msg-id | A76B25F2823E954C9E45E32FA49D70ECCD415423@mail.corp.perceptron.com обсуждение исходный текст |
| Ответ на | Re: Help with slow table update (Pawel Veselov <pawel.veselov@gmail.com>) |
| Ответы |
Re: Help with slow table update
|
| Список | pgsql-general |
From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Pawel Veselov
Sent: Tuesday, April 14, 2015 8:01 PM
To: Jim Nasby
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] Help with slow table update
[skipped]
This is where using sets becomes really tedious, as Postgres severely lacks an upsert-like statement.
I don't think there are joins allowed in UPDATE statement, so I will need to use WITH query, right?
Also, I'm not sure how LEFT JOIN will help me isolate and insert "missed" entries...
Would it be OK to replace upsert part with merging into a temp table, then deleting and inserting from temp table? Is there any penalty for insert/delete comparing to update?
[skipped]
Yes, you can do UPDATE with joins (http://www.postgresql.org/docs/9.4/static/sql-update.html) like this:
UPDATE table1 A SET col1 = B.col2
FROM table2 B
WHERE A.col3 = B.col4;
Regards,
Igor Neyman
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