Horton

Re: UPDATE of partition key

Amit Khandekar <amitdkhan.pg@gmail.com>

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From: Amit Khandekar <amitdkhan.pg@gmail.com>
To: David Fetter <david@fetter.org>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-02-16T06:50:54Z
Lists: pgsql-hackers 
On 15 February 2017 at 20:26, David Fetter <david@fetter.org> wrote:
> When an UPDATE can't happen, there are often ways to hint at
> what went wrong and how to correct it.  Violating a uniqueness
> constraint would be one example.
>
> When an UPDATE can't happen and the depth of the subtree is a
> plausible candidate for what prevents it, there might be a way to say
> so.
>
> Let's imagine a table called log with partitions on "stamp" log_YYYY
> and subpartitions, also on "stamp", log_YYYYMM.  If you do something
> like
>
>     UPDATE log_2017 SET "stamp"='2016-11-08 23:03:00' WHERE ...
>
> it's possible to know that it might have worked had the UPDATE taken
> place on log rather than on log_2017.
>
> Does that make sense, and if so, is it super invasive to HINT that?

Yeah, I think it should be possible to find the root partition with
the help of pg_partitioned_table, and then run ExecFindPartition()
again using the root. Will check. I am not sure right now how involved
that would turn out to be, but I think that logic would not change the
existing code, so in that sense it is not invasive.


-- 
Thanks,
-Amit Khandekar
EnterpriseDB Corporation
The Postgres Database 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.