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

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От Ashutosh Bapat
Тема Re: postgres_fdw join pushdown (was Re: Custom/Foreign-Join-APIs)
Дата
Msg-id CAFjFpRc0yEKX0v8pH8ckucYEg=o1-+aEjH2O_t3RXpf-2yD4eA@mail.gmail.com
обсуждение исходный текст
Ответ на Re: postgres_fdw join pushdown (was Re: Custom/Foreign-Join-APIs)  (Robert Haas <robertmhaas@gmail.com>)
Ответы Re: postgres_fdw join pushdown (was Re: Custom/Foreign-Join-APIs)
Re: postgres_fdw join pushdown (was Re: Custom/Foreign-Join-APIs)
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Дерево обсуждения


On Thu, Feb 4, 2016 at 4:30 AM, Robert Haas <robertmhaas@gmail.com> wrote:
On Wed, Feb 3, 2016 at 5:56 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Wed, Feb 3, 2016 at 12:08 PM, Ashutosh Bapat
> <ashutosh.bapat@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.
>
> Hmm, I think that GetPathForEPQRecheck() is a pretty terrible name.
> How about GetExistingJoinPath()?

GetExistingLocalJoinPath()? Used that.
 

Oops.  Hit Send too soon.  Also, how about writing if
(path->param_info != NULL) continue; instead of burying the core of
the function in another level of indentation?

Hmm. Done.
 
I think you should skip
paths that aren't parallel_safe, too, and the documentation should be
clear that this will find an unparameterized, parallel-safe joinpath
if one exists.

A query with FOR UPDATE/SHARE will be considered parallel unsafe in has_parallel_hazard_walker() and root->glob->parallelModeOK will be marked false. This implies that none of the base relations and hence join relations will be marked as consider_parallel. IIUC your logic, none of the queries with FOR UPDATE/SHARE will get a local path which is marked parallel_safe and thus join will not be pushed down. Why do you think we need to skip paths that aren't parallel_safe? I have left aside this change in the latest patches.

 

+                               ForeignPath *foreign_path;
+                               foreign_path = (ForeignPath
*)joinpath->outerjoinpath;

Maybe insert a blank line between here, and in the other, similar case.

Done.

Patches attached with the previous mail.
--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

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