| From: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
|---|---|
| To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | vignesh C <vignesh21(at)gmail(dot)com>, Jacob Champion <jchampion(at)timescale(dot)com>, Yura Sokolov <y(dot)sokolov(at)postgrespro(dot)ru>, Zhihong Yu <zyu(at)yugabyte(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, "Imai, Yoshikazu" <imai(dot)yoshikazu(at)jp(dot)fujitsu(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com> |
| Subject: | Re: Speed up transaction completion faster after many relations are accessed in a transaction |
| Date: | 2023-09-15 10:37:11 |
| Message-ID: | 2f3621b8-abb1-b13f-fb0b-45f358a8d183@iki.fi |
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| Thread: | |
| Lists: | pgsql-hackers |
On 11/09/2023 15:00, David Rowley wrote:
> On Wed, 5 Jul 2023 at 21:44, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
>>
>>> index 296dc82d2ee..edb8b6026e5 100644
>>> --- a/src/backend/commands/discard.c
>>> +++ b/src/backend/commands/discard.c
>>> @@ -71,7 +71,7 @@ DiscardAll(bool isTopLevel)
>>> Async_UnlistenAll();
>>> - LockReleaseAll(USER_LOCKMETHOD, true);
>>> + LockReleaseSession(USER_LOCKMETHOD);
>>> ResetPlanCache();
>>
>> This assumes that there are no transaction-level advisory locks. I think
>> that's OK. It took me a while to convince myself of that, though. I
>> think we need a high level comment somewhere that explains what
>> assumptions we make on which locks can be held in session mode and which
>> in transaction mode.
>
> Isn't it ok because DISCARD ALL cannot run inside a transaction block,
> so there should be no locks taken apart from possibly session-level
> locks?
Hmm, sounds valid. I think I convinced myself that it's OK through some
other reasoning, but I don't remember it now.
> I've added a call to LockAssertNoneHeld(false) in there.
I don't see it in the patch?
--
Heikki Linnakangas
Neon (https://neon.tech)
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