Horton

Re: ALTER TABLE .. DETACH PARTITION CONCURRENTLY

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Amit Langote <amitlangote09@gmail.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-04-26T12:40:54Z
Lists: pgsql-hackers 
Hello Amit,

On 2021-Apr-26, Amit Langote wrote:

> On Sat, Apr 24, 2021 at 8:31 AM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:

> > I haven't added a mechanism to verify this; but with asserts on, this
> > patch will crash if you have more than one.  I think the behavior is not
> > necessarily sane with asserts off, since you'll get an arbitrary
> > detach-Xmin assigned to the partdesc, depending on catalog scan order.
> 
> Maybe this is an ignorant question but is the plan to add an elog() in
> this code path or a check (and an ereport()) somewhere in
> ATExecDetachPartition() to prevent more than one partition ending up
> in detach-pending state?

Yeah, that's what I'm planning to do.

> Please allow me to study the patch a bit more closely and get back tomorrow.

Sure, thanks!

-- 
Álvaro Herrera       Valdivia, Chile
"But static content is just dynamic content that isn't moving!"
                http://smylers.hates-software.com/2007/08/15/fe244d0c.html

Commits

  1. Make detach-partition-concurrently-4 less timing sensitive

  2. Improve documentation on DETACH PARTITION lock levels

  3. Track detached partitions more accurately in partdescs

  4. Allow a partdesc-omitting-partitions to be cached

  5. Fix relcache inconsistency hazard in partition detach

  6. Don't add a redundant constraint when detaching a partition

  7. ALTER TABLE ... DETACH PARTITION ... CONCURRENTLY

  8. Let ALTER TABLE Phase 2 routines manage the relation pointer

  9. Check default partitions constraints while descending