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  1. doc: Clarify use of ACCESS EXCLUSIVE lock in various sections

  1. DROP INDEX docs - explicit lock naming

    Greg Rychlewski <greg.rychlewski@gmail.com> — 2021-03-30T14:33:46Z

    Hi,

While reading the documentation for DROP INDEX[1], I noticed the lock was
described colloquially as an "exclusive" lock, which made me pause for a
second because it's the same name as the EXCLUSIVE table lock.

The attached patch explicitly states that an ACCESS EXCLUSIVE lock is
acquired.

[1]
https://www.postgresql.org/docs/current/sql-dropindex.html

  2. Re: DROP INDEX docs - explicit lock naming

    Michael Paquier <michael@paquier.xyz> — 2021-03-31T00:47:16Z

    On Tue, Mar 30, 2021 at 10:33:46AM -0400, Greg Rychlewski wrote:
> While reading the documentation for DROP INDEX[1], I noticed the lock was
> described colloquially as an "exclusive" lock, which made me pause for a
> second because it's the same name as the EXCLUSIVE table lock.
> 
> The attached patch explicitly states that an ACCESS EXCLUSIVE lock is
> acquired.

Indeed, this could be read as ACCESS SHARE being allowed, but that's
never the case for any of the index code paths, except if CONCURRENTLY
is involved.  It is not the only place in the docs where we could do
more clarification.  For instance, reindex.sgml mentions twice an
exclusive lock but that should be an access exclusive lock.  To be
exact, I can spot 27 places under doc/ that could be improved.  Such
changes depend on the surrounding context, of course.
--
Michael

  3. Re: DROP INDEX docs - explicit lock naming

    Greg Rychlewski <greg.rychlewski@gmail.com> — 2021-03-31T03:29:17Z

    Thanks for pointing that out. I've attached a new patch with several other
updates where I felt confident the docs were referring to an ACCESS
EXCLUSIVE lock.

On Tue, Mar 30, 2021 at 8:47 PM Michael Paquier <michael@paquier.xyz> wrote:

> On Tue, Mar 30, 2021 at 10:33:46AM -0400, Greg Rychlewski wrote:
> > While reading the documentation for DROP INDEX[1], I noticed the lock was
> > described colloquially as an "exclusive" lock, which made me pause for a
> > second because it's the same name as the EXCLUSIVE table lock.
> >
> > The attached patch explicitly states that an ACCESS EXCLUSIVE lock is
> > acquired.
>
> Indeed, this could be read as ACCESS SHARE being allowed, but that's
> never the case for any of the index code paths, except if CONCURRENTLY
> is involved.  It is not the only place in the docs where we could do
> more clarification.  For instance, reindex.sgml mentions twice an
> exclusive lock but that should be an access exclusive lock.  To be
> exact, I can spot 27 places under doc/ that could be improved.  Such
> changes depend on the surrounding context, of course.
> --
> Michael
>

  4. Re: DROP INDEX docs - explicit lock naming

    Michael Paquier <michael@paquier.xyz> — 2021-04-01T06:32:27Z

    On Tue, Mar 30, 2021 at 11:29:17PM -0400, Greg Rychlewski wrote:
> Thanks for pointing that out. I've attached a new patch with several other
> updates where I felt confident the docs were referring to an ACCESS
> EXCLUSIVE lock.

Thanks, applied!  I have reviewed the whole and there is one place in
vacuum.sgml that could switch "exclusive lock" to "SHARE UPDATE
EXCLUSIVE lock" but I have left that out as it does not bring more
clarity in the text.  The change in indexam.sgml was partially wrong
as REINDEX CONCURRENTLY does not take an access exclusive lock, and I
have tweaked a bit the wording of pgrowlocks.sgml.
--
Michael

  5. Re: DROP INDEX docs - explicit lock naming

    Greg Rychlewski <greg.rychlewski@gmail.com> — 2021-04-01T12:26:50Z

    Thanks! I apologize, I added a commitfest entry for this and failed to add
it to my message: https://commitfest.postgresql.org/33/3053/.

This is my first time submitting a patch and I'm not sure if it needs to be
deleted now or if you are supposed to add yourself as a committer.

On Thu, Apr 1, 2021 at 2:32 AM Michael Paquier <michael@paquier.xyz> wrote:

> On Tue, Mar 30, 2021 at 11:29:17PM -0400, Greg Rychlewski wrote:
> > Thanks for pointing that out. I've attached a new patch with several
> other
> > updates where I felt confident the docs were referring to an ACCESS
> > EXCLUSIVE lock.
>
> Thanks, applied!  I have reviewed the whole and there is one place in
> vacuum.sgml that could switch "exclusive lock" to "SHARE UPDATE
> EXCLUSIVE lock" but I have left that out as it does not bring more
> clarity in the text.  The change in indexam.sgml was partially wrong
> as REINDEX CONCURRENTLY does not take an access exclusive lock, and I
> have tweaked a bit the wording of pgrowlocks.sgml.
> --
> Michael
>

  6. Re: DROP INDEX docs - explicit lock naming

    Michael Paquier <michael@paquier.xyz> — 2021-04-01T23:54:28Z

    On Thu, Apr 01, 2021 at 08:26:50AM -0400, Greg Rychlewski wrote:
> Thanks! I apologize, I added a commitfest entry for this and failed to add
> it to my message: https://commitfest.postgresql.org/33/3053/.
> 
> This is my first time submitting a patch and I'm not sure if it needs to be
> deleted now or if you are supposed to add yourself as a committer.

Thanks, I did not notice that.  The entry has been updated as it
should.
--
Michael