From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
Cc: | Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: UPDATE of partition key |
Date: | 2017-06-09 13:40:05 |
Message-ID: | CAA4eK1LWXc07C7LdWGq83eh9XYAZpKgLanr1TiXrTL00gwsbAw@mail.gmail.com |
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Lists: | pgsql-hackers |
On Thu, Jun 8, 2017 at 10:40 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Thu, Jun 8, 2017 at 7:01 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> On Thu, Jun 8, 2017 at 1:33 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> On Wed, Jun 7, 2017 at 5:46 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>>>> As far as I understand, it is to ensure that for deleted rows, nothing
>>>> more needs to be done. For example, see the below check in
>>>> ExecUpdate/ExecDelete.
>>>> if (!ItemPointerEquals(tupleid, &hufd.ctid))
>>>> {
>>>> ..
>>>> }
>>>> ..
>>>>
>>>> Also a similar check in ExecLockRows. Now for deleted rows, if the
>>>> t_ctid wouldn't point to itself, then in the mentioned functions, we
>>>> were not in a position to conclude that the row is deleted.
>>>
>>> Right, so we would have to find all such checks and change them to use
>>> some other method to conclude that the row is deleted. What method
>>> would we use?
>>
>> I think before doing above check we can simply check if ctid.ip_blkid
>> contains InvalidBlockNumber, then return an error.
>
> Hmm, OK. That case never happens today?
>
As per my understanding that case doesn't exist. I will verify again
once the patch is available. I can take a crack at it if Amit
Khandekar is busy with something else or is not comfortable in this
area.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
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