Horton

Re: ALTER TABLE .. DETACH PARTITION CONCURRENTLY

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Hao Wu <hawu@vmware.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Pg Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2020-09-10T20:54:24Z
Lists: pgsql-hackers

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On 2020-Aug-31, Hao Wu wrote:

> I tested the patch provided by Alvaro. It seems not well in REPEATABLE READ.

> -- the tuples from tpart_2 are gone.
> gpadmin=*# select * from tpart;
>  i  | j
> ----+----
>  10 | 10
>  50 | 50
> (2 rows)

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.

The attached v2, on current master, includes that change, as well as
fixes a couple of silly bugs in the previous one.

(Because of experimenting with git workflow I did not keep the 0001
part split in this one, but that part is unchanged from v1.)

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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