> On Fri, Jan 9, 2015 at 10:51 AM, Kouhei Kaigai <kai...@ak.jp.nec.com> wrote: > > When custom-scan node replaced a join-plan, it shall have at least two > > child plan-nodes. The callback handler of PlanCustomPath needs to be > > able to call create_plan_recurse() to transform the underlying > > path-nodes to plan-nodes, because this custom-scan node may take other > > built-in scan or sub-join nodes as its inner/outer input. > > In case of FDW, it shall kick any underlying scan relations to remote > > side, thus we may not expect ForeignScan has underlying plans... > > Do you have an example of this? > Yes, even though full code set is too large for patch submission...
https://github.com/pg-strom/devel/blob/master/src/gpuhashjoin.c#L1880 This create_gpuhashjoin_plan() is PlanCustomPath callback of GpuHashJoin. It takes GpuHashJoinPath inherited from CustomPath that has multiple underlying scan/join paths. Once it is called back from the backend, it also calls create_plan_recurse() to make inner/outer plan nodes according to the paths. In the result, we can see the following query execution plan that CustomScan takes underlying scan plans. postgres=# EXPLAIN SELECT * FROM t0 NATURAL JOIN t1 NATURAL JOIN t2; QUERY PLAN ---------------------------------------------------------------------------------- Custom Scan (GpuHashJoin) (cost=2968.00..140120.31 rows=3970922 width=143) Hash clause 1: (aid = aid) Hash clause 2: (bid = bid) Bulkload: On -> Custom Scan (GpuScan) on t0 (cost=500.00..57643.00 rows=4000009 width=77) -> Custom Scan (MultiHash) (cost=734.00..734.00 rows=40000 width=37) hash keys: aid nBatches: 1 Buckets: 46000 Memory Usage: 99.99% -> Seq Scan on t1 (cost=0.00..734.00 rows=40000 width=37) -> Custom Scan (MultiHash) (cost=734.00..734.00 rows=40000 width=37) hash keys: bid nBatches: 1 Buckets: 46000 Memory Usage: 49.99% -> Seq Scan on t2 (cost=0.00..734.00 rows=40000 width=37) (13 rows) Thanks, -- NEC OSS Promotion Center / PG-Strom Project KaiGai Kohei <kai...@ak.jp.nec.com> > -----Original Message----- > From: Robert Haas [mailto:robertmh...@gmail.com] > Sent: Thursday, January 15, 2015 2:07 AM > To: Kaigai Kouhei(海外 浩平) > Cc: Tom Lane; pgsql-hackers@postgreSQL.org; Shigeru Hanada > Subject: ##freemail## Re: Custom/Foreign-Join-APIs (Re: [HACKERS] [v9.5] > Custom Plan API) > > On Fri, Jan 9, 2015 at 10:51 AM, Kouhei Kaigai <kai...@ak.jp.nec.com> wrote: > > When custom-scan node replaced a join-plan, it shall have at least two > > child plan-nodes. The callback handler of PlanCustomPath needs to be > > able to call create_plan_recurse() to transform the underlying > > path-nodes to plan-nodes, because this custom-scan node may take other > > built-in scan or sub-join nodes as its inner/outer input. > > In case of FDW, it shall kick any underlying scan relations to remote > > side, thus we may not expect ForeignScan has underlying plans... > > Do you have an example of this? > > -- > Robert Haas > EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL > Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
