Horton

Re: Bug in row_number() optimization

Richard Guo <guofenglinux@gmail.com>

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From: Richard Guo <guofenglinux@gmail.com>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Sergey Shinderuk <s.shinderuk@postgrespro.ru>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, David Rowley <drowley@postgresql.org>
Date: 2022-11-25T03:00:27Z
Lists: pgsql-hackers 
On Fri, Nov 25, 2022 at 7:34 AM David Rowley <dgrowleyml@gmail.com> wrote:

> Since upper-level WindowAggs cannot reference values calculated in
> some lower-level WindowAgg, why can't we just NULLify the pointers
> instead? See attached.


Verified the problem is fixed with this patch.  I'm not familiar with
the WindowAgg execution codes.  As far as I understand, this patch works
because we set ecxt_aggnulls to true, making it a NULL value.  And the
top-level WindowAgg node's "Filter" is strict so that it can filter out
all the tuples that don't match the intermediate WindowAgg node's run
condition.  So I find the comments about "WindowAggs above us cannot
reference the result of another WindowAgg" confusing.  But maybe I'm
missing something.

Thanks
Richard

Commits

  1. Fix 32-bit build dangling pointer issue in WindowAgg

  2. Teach planner and executor about monotonic window funcs