From: | Michael Lewis <mlewis(at)entrata(dot)com> |
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To: | Mathieu Fenniak <mathieu(dot)fenniak(at)replicon(dot)com> |
Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Complex filters -> Bad row estimates -> bad query plan |
Date: | 2019-08-21 23:05:11 |
Message-ID: | CAHOFxGpnAX7x0s7sQ-mkNQVA3VQ7+65nOOFtU5mOLy_tk=k1Jg@mail.gmail.com |
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Thread: | |
Lists: | pgsql-general |
-- I'm thinking the OFFSET 0 create an optimization barrier that prevents
the planner from collapsing that sub-query into the top query, and enforces
ordering in the query?
That's my understanding. I think it is an optimizer hint by another name. I
used to put things in a CTE (which is always materialized until v12, which
will change it to inlined unless keyword MATERIALIZED is included) or I
would create a temp table if the dataset is expected to contain many rows
such that I can do ANALYZE pg_temp.table_table; so the optimizer has stats
to make good decisions.
Note- Replying to messages with a full quote of the conversation below your
comment (aka top-posting) is discouraged on these mailing lists. Please
quote the portion you are responding to and that's it.
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