Horton

Re: UPDATE of partition key

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Simon Riggs <simon@2ndquadrant.com>, Amit Khandekar <amitdkhan.pg@gmail.com>, Greg Stark <stark@mit.edu>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-05-17T10:29:16Z
Lists: pgsql-hackers 
On Mon, May 15, 2017 at 5:28 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Fri, May 12, 2017 at 3:07 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>> I agree with you that it might not be straightforward to make it work,
>> but now that earliest it can go is v11, do we want to try doing
>> something other than just documenting it.  What I could read from this
>> e-mail thread is that you are intending towards just documenting it
>> for the first cut of this feature. However, both Greg and Simon are of
>> opinion that we should do something about this and even patch Author
>> (Amit Khandekar) has shown some inclination to do something about this
>> point (return error to the user in some way), so I think we can't
>> ignore this point.
>>
>> I think now that we have some more time, it is better to try something
>> based on a couple of ideas floating in this thread to address this
>> point and see if we can come up with something doable without a big
>> architecture change.
>>
>> What is your take on this point now?
>
> I still don't think it's worth spending a bit on this, especially not
> with WARM probably gobbling up multiple bits.  Reclaiming the bits
> seems like a good idea, but spending one on this still seems to me
> like it's probably not the best use of our increasingly-limited supply
> of infomask bits.
>

I think we can do this even without using an additional infomask bit.
As suggested by Greg up thread, we can set InvalidBlockId in ctid to
indicate such an update.

>  Now, Simon and Greg may still feel otherwise, of
> course.
>
> I could get behind providing an option to turn this behavior on and
> off at the level of the partitioned table.
>

Sure that sounds like a viable option and we can set the default value
as false.  However, it might be better if we can detect the same
internally without big changes.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

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.