Horton

Re: ALTER TABLE .. DETACH PARTITION CONCURRENTLY

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Amit Langote <amitlangote09@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2021-03-21T18:14:20Z
Lists: pgsql-hackers 
On Sun, Mar 21, 2021 at 03:01:15PM -0300, Alvaro Herrera wrote:
> > But note that it doesn't check if an existing constraint "implies" the new
> > constraint - maybe it should.
> 
> Hm, I'm not sure I want to do that, because that means that if I later
> have to attach the partition again with the same partition bounds, then
> I might have to incur a scan to recheck the constraint.  I think we want
> to make the new constraint be as tight as possible ...

The ATTACH PARTITION checks if any existing constraint impilies the (proposed)
partition bounds, not just if constraints are equal.  So I'm suggesting to do
the same here.

-- 
Justin

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