Re: Foreign join pushdown vs EvalPlanQual

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>
Cc: robertmhaas(at)gmail(dot)com, kaigai(at)ak(dot)jp(dot)nec(dot)com, tgl(at)sss(dot)pgh(dot)pa(dot)us, pgsql-hackers(at)postgresql(dot)org, shigeru(dot)hanada(at)gmail(dot)com
Subject: Re: Foreign join pushdown vs EvalPlanQual
Date: 2015-11-12 10:33:33
Message-ID: 56446AFD.2050208@lab.ntt.co.jp
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Horiguchi-san,

On 2015/11/12 16:10, Kyotaro HORIGUCHI wrote:
>>> I really don't see why you're fighting on this point. Making this a
>>> generic feature will require only a few extra lines of code for FDW
>>> authors. If this were going to cause some great inconvenience for FDW
>>> authors, then I'd agree it isn't worth it. But I see zero evidence
>>> that this is actually the case.

>> Really? I think there would be not a little burden on an FDW author;
>> when postgres_fdw delegates to the subplan to the remote server, for
>> example, it would need to create a remote join query by looking at
>> tuples possibly fetched and stored in estate->es_epqTuple[], send the
>> query and receive the result during the callback routine.

> Do you mind that FDW cannot generate a plan so that make a tuple
> from eqpTules then apply fdw_quals from predefined executor
> nodes?

No. Please see my previous email. Sorry for my unfinished email.

Best regards,
Etsuro Fujita

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