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Fix bitmap AND/OR scans on the inside of a nestloop partition-wise join.

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reparameterize_path_by_child() failed to reparameterize BitmapAnd
and BitmapOr paths.  This matters only if such a path is chosen as
the inside of a nestloop partition-wise join, where we have to pass
in parameters from the outside of the nestloop.  If that did happen,
we generated a bad plan that would likely lead to crashes at execution.

This is not entirely reparameterize_path_by_child()'s fault though;
it's the victim of an ancient decision (my ancient decision, I think)
to not bother filling in param_info in BitmapAnd/Or path nodes.  That
caused the function to believe that such nodes and their children
contain no parameter references and so need not be processed.

In hindsight that decision looks pretty penny-wise and pound-foolish:
while it saves a few cycles during path node setup, we do commonly
need the information later.  In particular, by reversing the decision
and requiring valid param_info data in all nodes of a bitmap path
tree, we can get rid of indxpath.c's get_bitmap_tree_required_outer()
function, which computed the data on-demand.  It's not unlikely that
that nets out as a savings of cycles in many scenarios.  A couple
of other things in indxpath.c can be simplified as well.

While here, get rid of some cases in reparameterize_path_by_child()
that are visibly dead or useless, given that we only care about
reparameterizing paths that can be on the inside of a parameterized
nestloop.  This case reminds one of the maxim that untested code
probably does not work, so I'm unwilling to leave unreachable code
in this function.  (I did leave the T_Gather case in place even
though it's not reached in the regression tests.  It's not very
clear to me when the planner might prefer to put Gather below
rather than above a nestloop, but at least in principle the case
might be interesting.)

Per bug #16536, originally from Arne Roland but with a test case
by Andrew Gierth.  Back-patch to v11 where this code came in.

Discussion: https://postgr.es/m/16536-2213ee0b3aad41fd@postgresql.org
This commit is contained in:
Tom Lane
2020-07-14 18:56:49 -04:00
parent 1231a0b0ea
commit de797e8235
4 changed files with 212 additions and 158 deletions
Download Patch File Download Diff File Expand all files Collapse all files

104
src/test/regress/expected/partition_join.out
View File

@ -2082,3 +2082,107 @@ SELECT t1.a, t1.c, t2.b, t2.c FROM prt1 t1, prt2 t2 WHERE t1.a = t2.b AND t1.b =
Filter: (b = 0)
(16 rows)
--
-- Test some other plan types in a partitionwise join (unfortunately,
-- we need larger tables to get the planner to choose these plan types)
--
create temp table prtx1 (a integer, b integer, c integer)
partition by range (a);
create temp table prtx1_1 partition of prtx1 for values from (1) to (11);
create temp table prtx1_2 partition of prtx1 for values from (11) to (21);
create temp table prtx1_3 partition of prtx1 for values from (21) to (31);
create temp table prtx2 (a integer, b integer, c integer)
partition by range (a);
create temp table prtx2_1 partition of prtx2 for values from (1) to (11);
create temp table prtx2_2 partition of prtx2 for values from (11) to (21);
create temp table prtx2_3 partition of prtx2 for values from (21) to (31);
insert into prtx1 select 1 + i%30, i, i
from generate_series(1,1000) i;
insert into prtx2 select 1 + i%30, i, i
from generate_series(1,500) i, generate_series(1,10) j;
create index on prtx2 (b);
create index on prtx2 (c);
analyze prtx1;
analyze prtx2;
explain (costs off)
select * from prtx1
where not exists (select 1 from prtx2
where prtx2.a=prtx1.a and prtx2.b=prtx1.b and prtx2.c=123)
and a<20 and c=120;
QUERY PLAN
-------------------------------------------------------------
Append
-> Nested Loop Anti Join
-> Seq Scan on prtx1_1
Filter: ((a < 20) AND (c = 120))
-> Bitmap Heap Scan on prtx2_1
Recheck Cond: ((b = prtx1_1.b) AND (c = 123))
Filter: (a = prtx1_1.a)
-> BitmapAnd
-> Bitmap Index Scan on prtx2_1_b_idx
Index Cond: (b = prtx1_1.b)
-> Bitmap Index Scan on prtx2_1_c_idx
Index Cond: (c = 123)
-> Nested Loop Anti Join
-> Seq Scan on prtx1_2
Filter: ((a < 20) AND (c = 120))
-> Bitmap Heap Scan on prtx2_2
Recheck Cond: ((b = prtx1_2.b) AND (c = 123))
Filter: (a = prtx1_2.a)
-> BitmapAnd
-> Bitmap Index Scan on prtx2_2_b_idx
Index Cond: (b = prtx1_2.b)
-> Bitmap Index Scan on prtx2_2_c_idx
Index Cond: (c = 123)
(23 rows)
select * from prtx1
where not exists (select 1 from prtx2
where prtx2.a=prtx1.a and prtx2.b=prtx1.b and prtx2.c=123)
and a<20 and c=120;
a | b | c
---+-----+-----
1 | 120 | 120
(1 row)
explain (costs off)
select * from prtx1
where not exists (select 1 from prtx2
where prtx2.a=prtx1.a and (prtx2.b=prtx1.b+1 or prtx2.c=99))
and a<20 and c=91;
QUERY PLAN
-----------------------------------------------------------------
Append
-> Nested Loop Anti Join
-> Seq Scan on prtx1_1
Filter: ((a < 20) AND (c = 91))
-> Bitmap Heap Scan on prtx2_1
Recheck Cond: ((b = (prtx1_1.b + 1)) OR (c = 99))
Filter: (a = prtx1_1.a)
-> BitmapOr
-> Bitmap Index Scan on prtx2_1_b_idx
Index Cond: (b = (prtx1_1.b + 1))
-> Bitmap Index Scan on prtx2_1_c_idx
Index Cond: (c = 99)
-> Nested Loop Anti Join
-> Seq Scan on prtx1_2
Filter: ((a < 20) AND (c = 91))
-> Bitmap Heap Scan on prtx2_2
Recheck Cond: ((b = (prtx1_2.b + 1)) OR (c = 99))
Filter: (a = prtx1_2.a)
-> BitmapOr
-> Bitmap Index Scan on prtx2_2_b_idx
Index Cond: (b = (prtx1_2.b + 1))
-> Bitmap Index Scan on prtx2_2_c_idx
Index Cond: (c = 99)
(23 rows)
select * from prtx1
where not exists (select 1 from prtx2
where prtx2.a=prtx1.a and (prtx2.b=prtx1.b+1 or prtx2.c=99))
and a<20 and c=91;
a | b | c
---+----+----
2 | 91 | 91
(1 row)

45
src/test/regress/sql/partition_join.sql
View File

@ -453,3 +453,48 @@ ANALYZE prt2;
EXPLAIN (COSTS OFF)
SELECT t1.a, t1.c, t2.b, t2.c FROM prt1 t1, prt2 t2 WHERE t1.a = t2.b AND t1.b = 0 ORDER BY t1.a, t2.b;
--
-- Test some other plan types in a partitionwise join (unfortunately,
-- we need larger tables to get the planner to choose these plan types)
--
create temp table prtx1 (a integer, b integer, c integer)
partition by range (a);
create temp table prtx1_1 partition of prtx1 for values from (1) to (11);
create temp table prtx1_2 partition of prtx1 for values from (11) to (21);
create temp table prtx1_3 partition of prtx1 for values from (21) to (31);
create temp table prtx2 (a integer, b integer, c integer)
partition by range (a);
create temp table prtx2_1 partition of prtx2 for values from (1) to (11);
create temp table prtx2_2 partition of prtx2 for values from (11) to (21);
create temp table prtx2_3 partition of prtx2 for values from (21) to (31);
insert into prtx1 select 1 + i%30, i, i
from generate_series(1,1000) i;
insert into prtx2 select 1 + i%30, i, i
from generate_series(1,500) i, generate_series(1,10) j;
create index on prtx2 (b);
create index on prtx2 (c);
analyze prtx1;
analyze prtx2;
explain (costs off)
select * from prtx1
where not exists (select 1 from prtx2
where prtx2.a=prtx1.a and prtx2.b=prtx1.b and prtx2.c=123)
and a<20 and c=120;
select * from prtx1
where not exists (select 1 from prtx2
where prtx2.a=prtx1.a and prtx2.b=prtx1.b and prtx2.c=123)
and a<20 and c=120;
explain (costs off)
select * from prtx1
where not exists (select 1 from prtx2
where prtx2.a=prtx1.a and (prtx2.b=prtx1.b+1 or prtx2.c=99))
and a<20 and c=91;
select * from prtx1
where not exists (select 1 from prtx2
where prtx2.a=prtx1.a and (prtx2.b=prtx1.b+1 or prtx2.c=99))
and a<20 and c=91;