Horton

Re: Significant Execution Time Difference Between PG13.14 and PG16.4 for Query on information_schema Tables.

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To:
Cc: David Rowley <dgrowleyml@gmail.com>, Richard Guo <guofenglinux@gmail.com>, nikhil raj <nikhilraj474@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2024-08-27T23:37:56Z
Lists: pgsql-hackers, pgsql-general 
I wrote:
> That seems like a pretty fishy way to do it.  Are you saying that
> Memoize is never applicable if there aren't outer joins in the
> query?  Without OJs there probably won't be any PHVs.

Oh, scratch that, I see you mean this is an additional way to do it
not the only way to do it.  But I'm confused why it works for
	t1.two+1 AS c1
but not
	t1.two+t2.two AS c1
Those ought to look pretty much the same for this purpose.

			regards, tom lane

Commits

  1. Avoid inserting PlaceHolderVars in cases where pre-v16 PG did not.

  2. Remove one memoize test case added by commit 069d0ff02.