Re: [HACKERS] UPDATE of partition key - Mailing list pgsql-hackers

From Amit Khandekar
Subject Re: [HACKERS] UPDATE of partition key
Date
Msg-id CAJ3gD9fbZ+YAkeuK-YWEBuTJ4KNXKrEMxghqBWw+zLZ-d+xGUg@mail.gmail.com
Whole thread Raw
In response to Re: [HACKERS] UPDATE of partition key  (Rajkumar Raghuwanshi <rajkumar.raghuwanshi@enterprisedb.com>)
Responses Re: [HACKERS] UPDATE of partition key
List pgsql-hackers
On 25 July 2017 at 15:02, Rajkumar Raghuwanshi
<rajkumar.raghuwanshi@enterprisedb.com> wrote:
> On Mon, Jul 24, 2017 at 11:23 AM, Amit Khandekar <amitdkhan.pg@gmail.com>
> wrote:
>>
>>
>> Attached update-partition-key_v13.patch now contains this
>> make_resultrels_ordered.patch changes.
>>
>
> I have applied attach patch and got below observation.
>
> Observation :  if join producing multiple output rows for a given row to be
> modified. I am seeing here it is updating a row and also inserting rows in
> target table. hence after update total count of table got incremented.

Thanks for catching this Rajkumar.

So after the row to be updated is already moved to another partition,
when the next join output row corresponds to the same row which is
moved, that row is now deleted, so ExecDelete()=>heap_delete() gets
HeapTupleSelfUpdated, and this is not handled. So even when
ExecDelete() finds that the row is already deleted, we still call
ExecInsert(), so a new row is inserted.  In ExecDelete(), we should
indicate that the row is already deleted. In the existing patch, there
is a parameter concurrenty_deleted for ExecDelete() which indicates
that the row is concurrently deleted. I think we can make this
parameter for both of these purposes so as to avoid ExecInsert() for
both these scenarios. Will work on a patch.



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