| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: new heapcheck contrib module |
| Date: | 2020-04-20 20:03:33 |
| Message-ID: | CA+TgmoaT+3aFG8i6FA74HrivO3qPCodiyuUDQf1qhxH8SOuGug@mail.gmail.com |
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| Lists: | pgsql-hackers |
[ retrying from the email address I intended to use ]
On Mon, Apr 20, 2020 at 3:42 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> I don't think random interspersed uses of CLogTruncationLock are a good
> idea. If you move to only checking visibility after tuple fits into
> [relfrozenxid, nextXid), then you don't need to take any locks here, as
> long as a lock against vacuum is taken (which I think this should do
> anyway).
I think it would be *really* good to avoid ShareUpdateExclusiveLock
here. Running with only AccessShareLock would be a big advantage. I
agree that any use of CLogTruncationLock should not be "random", but I
don't see why the same method we use to make txid_status() safe to
expose to SQL shouldn't also be used here.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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