Horton

Re: ALTER TABLE .. DETACH PARTITION CONCURRENTLY

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Hao Wu <hawu@vmware.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2020-09-11T20:28:49Z
Lists: pgsql-hackers 
On Thu, Sep 10, 2020 at 4:54 PM Alvaro Herrera <alvherre@2ndquadrant.com> wrote:
> Interesting example, thanks.  It seems this can be fixed without
> breaking anything else by changing the planner so that it includes
> detached partitions when we are in a snapshot-isolation transaction.
> Indeed, the results from the detach-partition-concurrently-1.spec
> isolation test are more satisfying with this change.

Hmm, so I think the idea here is that since we're out-waiting plans
with the old partition descriptor by waiting for lock release, it's OK
for anyone who has a lock to keep using the old partition descriptor
as long as they continuously hold the lock. Is that right? I can't
think of a hole in that logic, but it's probably worth noting in the
comments, in case someone is tempted to change the way that we
out-wait plans with the old partition descriptor to some other
mechanism.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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