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: 2021-03-21T18:22:00Z
Lists: pgsql-hackers 
On 2021-Mar-21, Justin Pryzby wrote:

> 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.

So if we do that on DETACH, what would happen on ATTACH?

-- 
Álvaro Herrera                            39°49'30"S 73°17'W

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