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: Justin Pryzby <pryzby@telsasoft.com>
Cc: Amit Langote <amitlangote09@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2021-03-15T23:04:37Z
Lists: pgsql-hackers

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On 2021-Feb-26, Alvaro Herrera wrote:

> Hmm, but if we take this approach, then we're still vulnerable to the
> problem that somebody can do DETACH CONCURRENTLY and cancel the wait (or
> crash the server), then mess up the state before doing DETACH FINALIZE:
> when they cancel the wait, the lock will be released.
> 
> I think the right fix is to disallow any action on a partition which is
> pending detach other than DETACH FINALIZE.  (Didn't do that here.)

Here's a fixup patch to do it that way.  I tried running the commands
you showed and one of them immediately dies with the new error message;
I can't cause the bogus constraint to show up anymore.

I'll clean this up for a real submission tomorrow.

-- 
Álvaro Herrera                            39°49'30"S 73°17'W
"The Gord often wonders why people threaten never to come back after they've
been told never to return" (www.actsofgord.com)

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