Re: postgres_fdw join pushdown (was Re: Custom/Foreign-Join-APIs)

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 <robertmhaas(at)gmail(dot)com>
>> wrote:
>>> On Wed, Feb 3, 2016 at 12:08 PM, Ashutosh Bapat
>>> <ashutosh(dot)bapat(at)enterprisedb(dot)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.

+ if (root->parse->commandType == CMD_DELETE ||
+ root->parse->commandType == CMD_UPDATE ||
+ root->rowMarks)
+ {
+ epq_path = GetPathForEPQRecheck(joinrel);
+ if (!epq_path)
+ {
+ elog(DEBUG3, "could not push down foreign join because a local path
suitable for EPQ checks was not found");
+ return;
+ }
+ }

Best regards,
Etsuro Fujita