| From: | Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp> |
|---|---|
| To: | Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, kaigai(at)ak(dot)jp(dot)nec(dot)com |
| Cc: | robertmhaas(at)gmail(dot)com, pgsql-hackers(at)postgresql(dot)org, shigeru(dot)hanada(at)gmail(dot)com |
| Subject: | Re: Foreign join pushdown vs EvalPlanQual |
| Date: | 2015-10-01 08:51:02 |
| Message-ID: | 560CF3F6.3000104@lab.ntt.co.jp |
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| Lists: | pgsql-hackers |
On 2015/10/01 15:38, Kyotaro HORIGUCHI wrote:
>> I expect FDW driver needs to handle EPQ recheck in the case below:
>> * ForeignScan on base relation and it uses late row locking.
> I think this is indisputable.
I think so. But I think this case would probably be handled by the
existing RefetchForeignRow routine as I said upthread.
>> * ForeignScan on join relation, even if early locking.
> This could be unnecessary if the "foreign join" scan node can
> have its own rowmark of ROW_MARK_COPY.
That's an idea, but I'd vote for preserving the applicability of late
row locking to the foreign join case, allowing component foreign tables
involved in a foreign join to have different rowmark methods other than
ROW_MARK_COPY.
Best regards,
Etsuro Fujita
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