Horton

Re: UPDATE of partition key

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Amit Khandekar <amitdkhan.pg@gmail.com>
Cc: Dilip Kumar <dilipbalaut@gmail.com>, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-05-24T14:44:58Z
Lists: pgsql-hackers 
On Wed, May 24, 2017 at 2:47 PM, Amit Khandekar <amitdkhan.pg@gmail.com> wrote:
> On 18 May 2017 at 16:52, Amit Kapila <amit.kapila16@gmail.com> wrote:
>> On Wed, May 17, 2017 at 4:05 PM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
>>> On Wed, May 17, 2017 at 3:15 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>>>>> Earlier I thought that option1 is better but later I think that this
>>>>> can complicate the situation as we are firing first BR update then BR
>>>>> delete and can change the row multiple time and defining such
>>>>> behaviour can be complicated.
>>>>>
>>>>
>>>> If we have to go by this theory, then the option you have preferred
>>>> will still execute BR triggers for both delete and insert, so input
>>>> row can still be changed twice.
>>>
>>> Yeah, right as per my theory above Option3 have the same problem.
>>>
>>> But after putting some more thought I realised that only for "Before
>>> Update" or the "Before Insert" trigger row can be changed.
>>>
>>
>> Before Row Delete triggers can suppress the delete operation itself
>> which is kind of unintended in this case.  I think without the user
>> being aware it doesn't seem advisable to execute multiple BR triggers.
>
> By now, majority of the opinions have shown that they do not favour
> two triggers getting fired on a single update. Amit, do you consider
> option 2 as a valid option ?
>

Sounds sensible to me.

> That is, fire only UPDATE triggers. BR on
> source partition, and AR on destination partition. Do you agree that
> firing BR update trigger is essential since it can modify the row and
> even prevent the update from happening ?
>

Agreed.

Apart from above, there is one open issue [1] related to generating an
error for concurrent delete of row for which I have mentioned some way
of getting it done, do you want to try that option and see if you face
any issue in making the progress on that lines?

-- 
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.