Horton

Re: UPDATE of partition key

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Amit Khandekar <amitdkhan.pg@gmail.com>
Cc: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-03-04T07:19:55Z
Lists: pgsql-hackers 
On Thu, Mar 2, 2017 at 11:53 AM, Amit Khandekar <amitdkhan.pg@gmail.com> wrote:
> I think it does not make sense running after row triggers in case of
> row-movement. There is no update happened on that leaf partition. This
> reasoning can also apply to BR update triggers. But the reasons for
> having a BR trigger and AR triggers are quite different. Generally, a
> user needs to do some modifications to the row before getting the
> final NEW row into the database, and hence [s]he defines a BR trigger
> for that. And we can't just silently skip this step only because the
> final row went into some other partition; in fact the row-movement
> itself might depend on what the BR trigger did with the row. Whereas,
> AR triggers are typically written for doing some other operation once
> it is made sure the row is actually updated. In case of row-movement,
> it is not actually updated.

How about running the BR update triggers for the old partition and the
AR update triggers for the new partition?  It seems weird to run BR
update triggers but not AR update triggers.  Another option would be
to run BR and AR delete triggers and then BR and AR insert triggers,
emphasizing the choice to treat this update as a delete + insert, but
(as Amit Kh. pointed out to me when we were in a room together this
week) that precludes using the BEFORE trigger to modify the row.

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

Commits

  1. Avoid referencing off the end of subplan_partition_offsets.

  2. Allow UPDATE to move rows between partitions.

  3. Remove useless lookup of root partitioned rel in ExecInitModifyTable().

  4. Factor error generation out of ExecPartitionCheck.

  5. Minor preparatory refactoring for UPDATE row movement.

  6. Simplify and encapsulate tuple routing support code.

  7. Avoid coercing a whole-row variable that is already coerced.

  8. Use ResultRelInfo ** rather than ResultRelInfo * for tuple routing.

  9. Make RelationGetPartitionDispatchInfo expand depth-first.

  10. Expand partitioned tables in PartDesc order.

  11. Use a real RT index when setting up partition tuple routing.

  12. Fix transition tables for partition/inheritance.

  13. Fix confusion about number of subplans in partitioned INSERT setup.

  14. Prevent BEFORE triggers from violating partitioning constraints.

  15. Fire per-statement triggers on partitioned tables.

  16. Fix reporting of violations in ExecConstraints, again.

  17. Don't scan partitioned tables.

  18. Allow FDWs to push down quals without breaking EvalPlanQual rechecks.