Sorry, I misoperated on patch creation. Attached one is the correct version. -- NEC OSS Promotion Center / PG-Strom Project KaiGai Kohei <kai...@ak.jp.nec.com>
> -----Original Message----- > From: pgsql-hackers-ow...@postgresql.org > [mailto:pgsql-hackers-ow...@postgresql.org] On Behalf Of Kouhei Kaigai > Sent: Tuesday, March 03, 2015 6:31 PM > To: Kaigai Kouhei(海外 浩平); Robert Haas > Cc: Tom Lane; pgsql-hackers@postgreSQL.org; Shigeru Hanada > Subject: Re: Custom/Foreign-Join-APIs (Re: [HACKERS] [v9.5] Custom Plan API) > > The attached version of custom/foreign-join interface patch > fixes up the problem reported on the join-pushdown support > thread. > > The previous version referenced *_ps_tlist on setrefs.c, to > check whether the Custom/ForeignScan node is associated with > a particular base relation, or not. > This logic considered above nodes performs base relation scan, > if *_ps_tlist is valid. However, it was incorrect in case when > underlying pseudo-scan relation has empty targetlist. > Instead of the previous logic, it shall be revised to check > scanrelid itself. If zero, it means Custom/ForeignScan node is > not associated with a particular base relation, thus, its slot > descriptor for scan shall be constructed based on *_ps_tlist. > > > Also, I noticed a potential problem if CSP/FDW driver want to > displays expression nodes using deparse_expression() but > varnode within this expression does not appear in the *_ps_tlist. > For example, a remote query below shall return rows with two > columns. > > SELECT atext, btext FROM tbl_a, tbl_b WHERE aid = bid; > > Thus, ForeignScan will perform like as a scan on relation with > two columns, and FDW driver will set two TargetEntry on the > fdw_ps_tlist. If FDW is designed to keep the join condition > (aid = bid) using expression node form, it is expected to be > saved on custom/fdw_expr variable, then setrefs.c rewrites the > varnode according to *_ps_tlist. > It means, we also have to add *_ps_tlist both of "aid" and "bid" > to avoid failure on variable lookup. However, these additional > entries changes the definition of the slot descriptor. > So, I adjusted ExecInitForeignScan and ExecInitCustomScan to > use ExecCleanTypeFromTL(), not ExecTypeFromTL(), when it construct > the slot descriptor based on the *_ps_tlist. > It expects CSP/FDW drivers to add target-entries with resjunk=true, > if it wants to have additional entries for variable lookups on > EXPLAIN command. > > Fortunately or unfortunately, postgres_fdw keeps its remote query > in cstring form, so it does not need to add junk entries on the > fdw_ps_tlist. > > Thanks, > -- > NEC OSS Promotion Center / PG-Strom Project > KaiGai Kohei <kai...@ak.jp.nec.com> > > > > -----Original Message----- > > From: pgsql-hackers-ow...@postgresql.org > > [mailto:pgsql-hackers-ow...@postgresql.org] On Behalf Of Kouhei Kaigai > > Sent: Sunday, February 15, 2015 11:01 PM > > To: Kaigai Kouhei(海外 浩平); Robert Haas > > Cc: Tom Lane; pgsql-hackers@postgreSQL.org; Shigeru Hanada > > Subject: Re: Custom/Foreign-Join-APIs (Re: [HACKERS] [v9.5] Custom Plan API) > > > > The attached patch is a rebased version of join replacement with > > foreign-/custom-scan. Here is no feature updates at this moment > > but SGML documentation is added (according to Michael's comment). > > > > This infrastructure allows foreign-data-wrapper and custom-scan- > > provider to add alternative scan paths towards relations join. > > From viewpoint of the executor, it looks like a scan on a pseudo- > > relation that is materialized from multiple relations, even though > > FDW/CSP internally processes relations join with their own logic. > > > > Its basic idea is, (1) scanrelid==0 indicates this foreign/custom > > scan node runs on a pseudo relation and (2) fdw_ps_tlist and > > custom_ps_tlist introduce the definition of the pseudo relation, > > because it is not associated with a tangible relation unlike > > simple scan case, thus planner cannot know the expected record > > type to be returned without these additional information. > > These two enhancement enables extensions to process relations > > join internally, and to perform as like existing scan node from > > viewpoint of the core backend. > > > > Also, as an aside. I had a discussion with Hanada-san about this > > interface off-list. He had an idea to keep create_plan_recurse() > > static, using a special list field in CustomPath structure to > > chain underlying Path node. If core backend translate the Path > > node to Plan node if valid list given, extension does not need to > > call create_plan_recurse() by itself. > > I have no preference about this. Does anybody have opinion? > > > > Thanks, > > -- > > NEC OSS Promotion Center / PG-Strom Project > > KaiGai Kohei <kai...@ak.jp.nec.com> > > > > > > > -----Original Message----- > > > From: pgsql-hackers-ow...@postgresql.org > > > [mailto:pgsql-hackers-ow...@postgresql.org] On Behalf Of Kouhei Kaigai > > > Sent: Thursday, January 15, 2015 8:03 AM > > > To: Robert Haas > > > Cc: Tom Lane; pgsql-hackers@postgreSQL.org; Shigeru Hanada > > > Subject: 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? > > > > > > > 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
pgsql-v9.5-custom-join.v6.patch
Description: pgsql-v9.5-custom-join.v6.patch
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