On Mon, Feb 8, 2021 at 3:43 PM Andy Fan <zhihui.fan1...@gmail.com> wrote:
> > > On Mon, Jan 25, 2021 at 10:21 AM Andy Fan <zhihui.fan1...@gmail.com> > wrote: > >> >> >> On Sun, Jan 24, 2021 at 6:34 PM Andy Fan <zhihui.fan1...@gmail.com> >> wrote: >> >>> Hi: >>> >>> I recently found a use case like this. SELECT * FROM p, q WHERE >>> p.partkey = >>> q.colx AND (q.colx = $1 OR q.colx = $2); Then we can't do either >>> planning time >>> partition prune or init partition prune. Even though we have run-time >>> partition pruning work at last, it is too late in some cases since we >>> have >>> to init all the plan nodes in advance. In my case, there are 10+ >>> partitioned relation in one query and the execution time is short, so >>> the >>> init plan a lot of plan nodes cares a lot. >>> >>> The attached patches fix this issue. It just get the "p.partkey = q.colx" >>> case in root->eq_classes or rel->joinlist (outer join), and then check >>> if there >>> is some baserestrictinfo in another relation which can be used for >>> partition >>> pruning. To make the things easier, both partkey and colx must be Var >>> expression in implementation. >>> >>> - v1-0001-Make-some-static-functions-as-extern-and-extend-C.patch >>> >>> Just some existing refactoring and extending ChangeVarNodes to be able >>> to change var->attno. >>> >>> - v1-0002-Build-some-implied-pruning-quals-to-extend-the-us.patch >>> >>> Do the real job. >>> >>> Thought? >>> >>> >>> >>> -- >>> Best Regards >>> Andy Fan (https://www.aliyun.com/) >>> >> >> >> Some results from this patch. >> >> create table p (a int, b int, c character varying(8)) partition by >> list(c); >> create table p1 partition of p for values in ('000001'); >> create table p2 partition of p for values in ('000002'); >> create table p3 partition of p for values in ('000003'); >> create table q (a int, c character varying(8), b int) partition by >> list(c); >> create table q1 partition of q for values in ('000001'); >> create table q2 partition of q for values in ('000002'); >> create table q3 partition of q for values in ('000003'); >> >> Before the patch: >> postgres=# explain (costs off) select * from p inner join q on p.c = q.c >> and q.c > '000002'; >> QUERY PLAN >> ---------------------------------------------------- >> Hash Join >> Hash Cond: ((p.c)::text = (q.c)::text) >> -> Append >> -> Seq Scan on p1 p_1 >> -> Seq Scan on p2 p_2 >> -> Seq Scan on p3 p_3 >> -> Hash >> -> Seq Scan on q3 q >> Filter: ((c)::text > '000002'::text) >> (9 rows) >> >> After the patch: >> >> QUERY PLAN >> ---------------------------------------------------- >> Hash Join >> Hash Cond: ((p.c)::text = (q.c)::text) >> -> Seq Scan on p3 p >> -> Hash >> -> Seq Scan on q3 q >> Filter: ((c)::text > '000002'::text) >> (6 rows) >> >> >> Before the patch: >> postgres=# explain (costs off) select * from p inner join q on p.c = q.c >> and (q.c = '000002' or q.c = '000001'); >> QUERY PLAN >> >> -------------------------------------------------------------------------------------------- >> Hash Join >> Hash Cond: ((p.c)::text = (q.c)::text) >> -> Append >> -> Seq Scan on p1 p_1 >> -> Seq Scan on p2 p_2 >> -> Seq Scan on p3 p_3 >> -> Hash >> -> Append >> -> Seq Scan on q1 q_1 >> Filter: (((c)::text = '000002'::text) OR ((c)::text >> = '000001'::text)) >> -> Seq Scan on q2 q_2 >> Filter: (((c)::text = '000002'::text) OR ((c)::text >> = '000001'::text)) >> (12 rows) >> >> After the patch: >> QUERY PLAN >> >> -------------------------------------------------------------------------------------------- >> Hash Join >> Hash Cond: ((p.c)::text = (q.c)::text) >> -> Append >> -> Seq Scan on p1 p_1 >> -> Seq Scan on p2 p_2 >> -> Hash >> -> Append >> -> Seq Scan on q1 q_1 >> Filter: (((c)::text = '000002'::text) OR ((c)::text >> = '000001'::text)) >> -> Seq Scan on q2 q_2 >> Filter: (((c)::text = '000002'::text) OR ((c)::text >> = '000001'::text)) >> (11 rows) >> >> Before the patch: >> postgres=# explain (costs off) select * from p left join q on p.c = q.c >> where (q.c = '000002' or q.c = '000001'); >> QUERY PLAN >> >> -------------------------------------------------------------------------------------------- >> Hash Join >> Hash Cond: ((p.c)::text = (q.c)::text) >> -> Append >> -> Seq Scan on p1 p_1 >> -> Seq Scan on p2 p_2 >> -> Seq Scan on p3 p_3 >> -> Hash >> -> Append >> -> Seq Scan on q1 q_1 >> Filter: (((c)::text = '000002'::text) OR ((c)::text >> = '000001'::text)) >> -> Seq Scan on q2 q_2 >> Filter: (((c)::text = '000002'::text) OR ((c)::text >> = '000001'::text)) >> (12 rows) >> >> After the patch: >> QUERY PLAN >> >> -------------------------------------------------------------------------------------------- >> Hash Join >> Hash Cond: ((p.c)::text = (q.c)::text) >> -> Append >> -> Seq Scan on p1 p_1 >> -> Seq Scan on p2 p_2 >> -> Hash >> -> Append >> -> Seq Scan on q1 q_1 >> Filter: (((c)::text = '000002'::text) OR ((c)::text >> = '000001'::text)) >> -> Seq Scan on q2 q_2 >> Filter: (((c)::text = '000002'::text) OR ((c)::text >> = '000001'::text)) >> (11 rows) >> >> -- >> Best Regards >> Andy Fan (https://www.aliyun.com/) >> > > > Here is a performance test regarding this patch. In the following simple > case, > we can get 3x faster than before. > > create table p (a int, b int, c int) partition by list(c); > select 'create table p_'||i||' partition of p for values in (' || i || > ');' from generate_series(1, 100)i; \gexec > insert into p select i, i, i from generate_series(1, 100)i; > create table m as select * from p; > analyze m; > analyze p; > > test sql: select * from m, p where m.c = p.c and m.c in (3, 10); > > With this patch: 1.1ms > Without this patch: 3.4ms > > I'm happy with the result and the implementation, I have add this into > commitfest https://commitfest.postgresql.org/32/2975/ > > Thanks. > > -- > Best Regards > Andy Fan (https://www.aliyun.com/) > Rebase to the current latest commit 678d0e239b. -- Best Regards Andy Fan (https://www.aliyun.com/)
v2-0002-Build-some-implied-pruning-quals-to-extend-the-us.patch
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v2-0001-Make-some-static-functions-as-extern-and-extend-C.patch
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