From: | Richard Guo <guofenglinux(at)gmail(dot)com> |
---|---|
To: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
Cc: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Andrew Kane <andrew(at)ankane(dot)org>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Xiaoran Wang <fanfuxiaoran(at)gmail(dot)com> |
Subject: | Re: Avoid computing ORDER BY junk columns unnecessarily |
Date: | 2023-12-26 03:18:16 |
Message-ID: | CAMbWs49_r8dKUyjyNUw2KRX8hTxEWz0d8X=gjd=ezyUwoFtCng@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
On Fri, Dec 22, 2023 at 2:38 AM Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
> v1-0004-Omit-columns-from-final-tlist-that-were-only-need.patch
>
> The main patch in this series.
This patch filters out the junk columns created for ORDER BY/GROUP BY,
and retains the junk columns created for RowLocks. I'm afraid this may
have a problem about out-of-order resnos. For instance,
create table mytable (foo text, bar text);
# explain select foo from mytable order by bar for update of mytable;
server closed the connection unexpectedly
This query triggers another Assert in apply_tlist_labeling:
Assert(dest_tle->resno == src_tle->resno);
At first there are three TargetEntry items: foo, bar and ctid, with
resnos being 1, 2 and 3. And then the second item 'bar' is removed,
leaving only two items: foo and ctid, with resnos being 1 and 3. So now
we have a missing resno, and finally hit the Assert.
Thanks
Richard
From | Date | Subject | |
---|---|---|---|
Next Message | Anton A. Melnikov | 2023-12-26 04:38:58 | Re: Some performance degradation in REL_16 vs REL_15 |
Previous Message | Amit Kapila | 2023-12-26 03:14:44 | Re: Track in pg_replication_slots the reason why slots conflict? |