Re: A performance issue with Memoize
| От | Richard Guo |
|---|---|
| Тема | Re: A performance issue with Memoize |
| Дата | |
| Msg-id | CAMbWs4-3oaHkAENPYn-qg8XhBv3WnwbSGq07GDf-j0=dM-jZ3w@mail.gmail.com обсуждение исходный текст |
| Ответ на | A performance issue with Memoize (Richard Guo <guofenglinux@gmail.com>) |
| Список | pgsql-hackers |
On Fri, Oct 20, 2023 at 6:40 PM Richard Guo <guofenglinux@gmail.com> wrote:
I haven't thought thoroughly about the fix yet. But one way I'm
thinking is that in create_subqueryscan_plan() we can first add the
subquery's subplan_params to root->curOuterParams, and then replace
outer-relation Vars in scan_clauses afterwards. That can make us be
able to share the same PARAM_EXEC slot for the same Var that both
belongs to the subquery's uplevel vars and to the NestLoop's
outer-relation vars. To be concrete, something like attached.
After some more thought, I think this is the right way to fix this
issue. The idea here is to make sure that the same NLP Var shares the
same PARAM_EXEC slot. This change can also help to save PARAM_EXEC
slots (which is trivial though since slots are very cheap).
Thanks
Richard
issue. The idea here is to make sure that the same NLP Var shares the
same PARAM_EXEC slot. This change can also help to save PARAM_EXEC
slots (which is trivial though since slots are very cheap).
Thanks
Richard
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