Horton

Re: Declarative partitioning - another take

Alvaro Herrera <alvherre@2ndquadrant.com>

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From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, Amit Langote <amitlangote09@gmail.com>, Dmitry Ivanov <d.ivanov@postgrespro.ru>, Michael Paquier <michael.paquier@gmail.com>, Andres Freund <andres@anarazel.de>, Erik Rijkers <er@xs4all.nl>, Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>, Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Pg Hackers <pgsql-hackers@postgresql.org>, pgsql-hackers-owner@postgresql.org
Date: 2016-12-20T15:27:05Z
Lists: pgsql-hackers 
Robert Haas wrote:
> On Tue, Dec 20, 2016 at 4:51 AM, Alvaro Herrera
> <alvherre@2ndquadrant.com> wrote:
> > Amit Langote wrote:
> >
> >> diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
> >> index 1c219b03dd..6a179596ce 100644
> >> --- a/src/backend/commands/tablecmds.c
> >> +++ b/src/backend/commands/tablecmds.c
> >> @@ -13297,8 +13297,10 @@ ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd)
> >>               }
> >>       }
> >>
> >> +     /* It's safe to skip the validation scan after all */
> >>       if (skip_validate)
> >> -             elog(NOTICE, "skipping scan to validate partition constraint");
> >> +             ereport(INFO,
> >> +                             (errmsg("skipping scan to validate partition constraint")));
> >
> > Why not just remove the message altogether?
> 
> That's certainly an option.  It might be noise in some situations.  On
> the other hand, it affects whether attaching the partition is O(1) or
> O(n), so somebody might well want to know.  Or maybe they might be
> more likely to want a message in the reverse situation, telling them
> that the partition constraint DOES need to be validated.  I'm not sure
> what the best user interface is here; thoughts welcome.

Even if we decide to keep the message, I think it's not very good
wording anyhow; as a translator I disliked it on sight.  Instead of
"skipping scan to validate" I would use "skipping validation scan",
except that it's not clear what it is we're validating.  Mentioning
partition constraint in errcontext() doesn't like a great solution, but
I can't think of anything better.

(We have the table_rewrite event trigger, for a very similar use case.)

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

Commits

  1. Fix typo.

  2. Document trigger-firing behavior for inheritance/partitioning.

  3. Fire per-statement triggers on partitioned tables.

  4. Set ecxt_scantuple correctly for tuple routing.

  5. Fix interaction of partitioned tables with BulkInsertState.

  6. Avoid core dump for empty prepared statement in an aborted transaction.

  7. Fix some problems in check_new_partition_bound().

  8. Remove unnecessary arguments from partitioning functions.

  9. Fix reporting of constraint violations for table partitioning.

  10. Fix tuple routing in cases where tuple descriptors don't match.

  11. Invalid parent's relcache after CREATE TABLE .. PARTITION OF.

  12. Doc: improve documentation about inheritance.