On Thu, Feb 4, 2016 at 3:28 PM, Etsuro Fujita <fujita.ets...@lab.ntt.co.jp>

> On 2016/02/04 17:58, Etsuro Fujita wrote:
>> On 2016/02/04 8:00, Robert Haas wrote:
>>> On Wed, Feb 3, 2016 at 5:56 PM, Robert Haas <robertmh...@gmail.com>
>>> wrote:
>>>> On Wed, Feb 3, 2016 at 12:08 PM, Ashutosh Bapat
>>>> <ashutosh.ba...@enterprisedb.com> wrote:
>>>>> PFA patches with naming conventions similar to previous ones.
>>>>> pg_fdw_core_v7.patch: core changes
>>>>> pg_fdw_join_v7.patch: postgres_fdw changes for join pushdown
>>>>> pg_join_pd_v7.patch: combined patch for ease of testing.
> One more: I think the following in postgresGetForeignJoinPaths() is a good
> idea, but I think it's okay to just check whether root->rowMarks is
> non-NIL, because that since we have rowmarks for all base relations except
> the target, if we have root->parse->commandType==CMD_DELETE (or
> root->parse->commandType==CMD_UPDATE), then there would be at least one
> non-target base relation in the joinrel, which would have a rowmark.
Sorry, I am unable to understand it fully. But what you are suggesting that
if there are root->rowMarks, then we are sure that there is at least one
base relation apart from the target, which needs locking rows. Even if we
don't have one, still changes in a row of target relation after it was
scanned, can result in firing EPQ check, which would need the local plan to
be executed, thus even if root->rowMarks is NIL, EPQ check can fire and we
will need alternate local plan.

Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

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