| From: | Michael Lewis <mlewis(at)entrata(dot)com> |
|---|---|
| To: | A Shaposhnikov <artyom(at)gmail(dot)com> |
| Cc: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, pgsql-general <pgsql-general(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: increasing effective_cache_size slows down join queries by a factor of 4000x |
| Date: | 2022-02-15 05:44:11 |
| Message-ID: | CAHOFxGojXjwzZTkFBqQtxJOTJKkD8Qnu38PqGp2dm-nTN6mMZw@mail.gmail.com |
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| Thread: | |
| Lists: | pgsql-general |
I think that theoretically if the planner sees a condition like
a.column1 > constant_value, and it also has a condition like a.column1 =
b.column2 then it could autogenerate the b.column2 > constant_value
condition. And of course > could be <, <=, >= and <>
But I could be wrong, particularly with respect to nulls and how = is
mostly the same as 'is not distinct from' except for 'select null = null'
being null and 'select null is not distinct from null' being true. Perhaps
if either/both columns have a not null constraint, then this could still be
done. Whether or not it should be a separate question.
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| Previous Message | A Shaposhnikov | 2022-02-15 00:06:34 | Re: increasing effective_cache_size slows down join queries by a factor of 4000x |