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>, Amit Kapila <amit.kapila16@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-06-21T20:27:42Z
Lists: pgsql-hackers 
On Wed, Jun 21, 2017 at 1:38 PM, Amit Khandekar <amitdkhan.pg@gmail.com> wrote:
>>> Yep, it's more appropriate to use
>>> ModifyTableState->rootResultRelationInfo->ri_RelationDesc somehow.  That
>>> is, if answer to the question I raised above is positive.
>
> From what I had checked earlier when coding that part,
> rootResultRelInfo is NULL in case of inserts, unless something has
> changed in later commits. That's the reason I decided to use the first
> resultRelInfo.

We're just going around in circles here.  Saying that you decided to
use the first child's resultRelInfo because you didn't have a
resultRelInfo for the parent is an explanation of why you wrote the
code the way you did, but that doesn't make it correct.  I want to
know why you think it's correct.

I think it's probably wrong, because it seems to me that if the INSERT
code needs to use the parent's ResultRelInfo rather than the first
child's ResultRelInfo, the UPDATE code probably needs to do the same.
Commit d3cc37f1d801a6b5cad9bf179274a8d767f1ee50 got rid of
resultRelInfos for non-leaf partitions, and commit
e180c8aa8caf5c55a273d4a8e6092e77ff3cff10 added the resultRelInfo back
for the topmost parent, because otherwise it didn't work correctly.
If every partition in the hierarchy has a different attribute
ordering, then it seems to me that it must surely matter which of
those attribute orderings we pick.  It's hard to imagine that we can
pick *either* the parent's attribute ordering *or* that of the first
child and nothing will be different - the attribute numbers inside the
returning lists and WCOs we create have got to get used somehow, so
surely it matters which attribute numbers we use, doesn't it?

-- 
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.