On Thu, Jan 15, 2015 at 8:02 AM, Kouhei Kaigai <kai...@ak.jp.nec.com> wrote:
> > 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) > Where are we on this? AFAIK, we have now a feature with no documentation and no example in-core to test those custom routine APIs, hence moved to next CF. -- Michael
