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Fix thinko in new logic about pushing down non-nullability constraints:
constraints appearing in outer-join qualification clauses are restricted as to when and where they can be pushed down. Add regression test to catch future errors in this area.
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-8
lines changed

3 files changed

+192
-8
lines changed

‎src/backend/optimizer/prep/prepjointree.c

Lines changed: 30 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,7 @@
1616
*
1717
*
1818
* IDENTIFICATION
19-
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.5 2003/02/09 23:57:19 tgl Exp $
19+
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.6 2003/02/10 17:08:50 tgl Exp $
2020
*
2121
*-------------------------------------------------------------------------
2222
*/
@@ -694,23 +694,45 @@ reduce_outer_joins_pass2(Node *jtnode,
694694
/* Only recurse if there's more to do below here */
695695
if (left_state->contains_outer || right_state->contains_outer)
696696
{
697+
Relids local_nonnullable;
697698
Relids pass_nonnullable;
698699

699700
/*
700-
* Scan join quals to see if we can add any nonnullability
701-
* constraints. (Okay to do this even if join is still outer.)
701+
* If this join is (now) inner, we can add any nonnullability
702+
* constraints its quals provide to those we got from above.
703+
* But if it is outer, we can only pass down the local constraints
704+
* into the nullable side, because an outer join never eliminates
705+
* any rows from its non-nullable side. If it's a FULL join then
706+
* it doesn't eliminate anything from either side.
702707
*/
703-
pass_nonnullable = find_nonnullable_rels(j->quals, true);
704-
pass_nonnullable = bms_add_members(pass_nonnullable,
705-
nonnullable_rels);
706-
/* And recurse as needed */
708+
if (jointype != JOIN_FULL)
709+
{
710+
local_nonnullable = find_nonnullable_rels(j->quals, true);
711+
local_nonnullable = bms_add_members(local_nonnullable,
712+
nonnullable_rels);
713+
}
714+
else
715+
local_nonnullable = NULL; /* no use in calculating it */
716+
707717
if (left_state->contains_outer)
718+
{
719+
if (jointype == JOIN_INNER || jointype == JOIN_RIGHT)
720+
pass_nonnullable = local_nonnullable;
721+
else
722+
pass_nonnullable = nonnullable_rels;
708723
reduce_outer_joins_pass2(j->larg, left_state, parse,
709724
pass_nonnullable);
725+
}
710726
if (right_state->contains_outer)
727+
{
728+
if (jointype == JOIN_INNER || jointype == JOIN_LEFT)
729+
pass_nonnullable = local_nonnullable;
730+
else
731+
pass_nonnullable = nonnullable_rels;
711732
reduce_outer_joins_pass2(j->rarg, right_state, parse,
712733
pass_nonnullable);
713-
bms_free(pass_nonnullable);
734+
}
735+
bms_free(local_nonnullable);
714736
}
715737
}
716738
else

‎src/test/regress/expected/join.out

Lines changed: 123 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2004,6 +2004,129 @@ NATURAL FULL JOIN
20042004
dd | | 42 | 2 |
20052005
(4 rows)
20062006

2007+
-- Test for propagation of nullability constraints into sub-joins
2008+
create temp table x (x1 int, x2 int);
2009+
insert into x values (1,11);
2010+
insert into x values (2,22);
2011+
insert into x values (3,null);
2012+
insert into x values (4,44);
2013+
insert into x values (5,null);
2014+
create temp table y (y1 int, y2 int);
2015+
insert into y values (1,111);
2016+
insert into y values (2,222);
2017+
insert into y values (3,333);
2018+
insert into y values (4,null);
2019+
select * from x;
2020+
x1 | x2
2021+
----+----
2022+
1 | 11
2023+
2 | 22
2024+
3 |
2025+
4 | 44
2026+
5 |
2027+
(5 rows)
2028+
2029+
select * from y;
2030+
y1 | y2
2031+
----+-----
2032+
1 | 111
2033+
2 | 222
2034+
3 | 333
2035+
4 |
2036+
(4 rows)
2037+
2038+
select * from x left join y on (x1 = y1 and x2 is not null);
2039+
x1 | x2 | y1 | y2
2040+
----+----+----+-----
2041+
1 | 11 | 1 | 111
2042+
2 | 22 | 2 | 222
2043+
3 | | |
2044+
4 | 44 | 4 |
2045+
5 | | |
2046+
(5 rows)
2047+
2048+
select * from x left join y on (x1 = y1 and y2 is not null);
2049+
x1 | x2 | y1 | y2
2050+
----+----+----+-----
2051+
1 | 11 | 1 | 111
2052+
2 | 22 | 2 | 222
2053+
3 | | 3 | 333
2054+
4 | 44 | |
2055+
5 | | |
2056+
(5 rows)
2057+
2058+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
2059+
on (x1 = xx1);
2060+
x1 | x2 | y1 | y2 | xx1 | xx2
2061+
----+----+----+-----+-----+-----
2062+
1 | 11 | 1 | 111 | 1 | 11
2063+
2 | 22 | 2 | 222 | 2 | 22
2064+
3 | | 3 | 333 | 3 |
2065+
4 | 44 | 4 | | 4 | 44
2066+
5 | | | | 5 |
2067+
(5 rows)
2068+
2069+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
2070+
on (x1 = xx1 and x2 is not null);
2071+
x1 | x2 | y1 | y2 | xx1 | xx2
2072+
----+----+----+-----+-----+-----
2073+
1 | 11 | 1 | 111 | 1 | 11
2074+
2 | 22 | 2 | 222 | 2 | 22
2075+
3 | | 3 | 333 | |
2076+
4 | 44 | 4 | | 4 | 44
2077+
5 | | | | |
2078+
(5 rows)
2079+
2080+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
2081+
on (x1 = xx1 and y2 is not null);
2082+
x1 | x2 | y1 | y2 | xx1 | xx2
2083+
----+----+----+-----+-----+-----
2084+
1 | 11 | 1 | 111 | 1 | 11
2085+
2 | 22 | 2 | 222 | 2 | 22
2086+
3 | | 3 | 333 | 3 |
2087+
4 | 44 | 4 | | |
2088+
5 | | | | |
2089+
(5 rows)
2090+
2091+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
2092+
on (x1 = xx1 and xx2 is not null);
2093+
x1 | x2 | y1 | y2 | xx1 | xx2
2094+
----+----+----+-----+-----+-----
2095+
1 | 11 | 1 | 111 | 1 | 11
2096+
2 | 22 | 2 | 222 | 2 | 22
2097+
3 | | 3 | 333 | |
2098+
4 | 44 | 4 | | 4 | 44
2099+
5 | | | | |
2100+
(5 rows)
2101+
2102+
-- these should NOT give the same answers as above
2103+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
2104+
on (x1 = xx1) where (x2 is not null);
2105+
x1 | x2 | y1 | y2 | xx1 | xx2
2106+
----+----+----+-----+-----+-----
2107+
1 | 11 | 1 | 111 | 1 | 11
2108+
2 | 22 | 2 | 222 | 2 | 22
2109+
4 | 44 | 4 | | 4 | 44
2110+
(3 rows)
2111+
2112+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
2113+
on (x1 = xx1) where (y2 is not null);
2114+
x1 | x2 | y1 | y2 | xx1 | xx2
2115+
----+----+----+-----+-----+-----
2116+
1 | 11 | 1 | 111 | 1 | 11
2117+
2 | 22 | 2 | 222 | 2 | 22
2118+
3 | | 3 | 333 | 3 |
2119+
(3 rows)
2120+
2121+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
2122+
on (x1 = xx1) where (xx2 is not null);
2123+
x1 | x2 | y1 | y2 | xx1 | xx2
2124+
----+----+----+-----+-----+-----
2125+
1 | 11 | 1 | 111 | 1 | 11
2126+
2 | 22 | 2 | 222 | 2 | 22
2127+
4 | 44 | 4 | | 4 | 44
2128+
(3 rows)
2129+
20072130
--
20082131
-- Clean up
20092132
--

‎src/test/regress/sql/join.sql

Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -292,6 +292,45 @@ NATURAL FULL JOIN
292292
(SELECT name, n as s3_n FROM t3) as s3
293293
) ss2;
294294

295+
296+
-- Test for propagation of nullability constraints into sub-joins
297+
298+
create temp table x (x1 int, x2 int);
299+
insert into x values (1,11);
300+
insert into x values (2,22);
301+
insert into x values (3,null);
302+
insert into x values (4,44);
303+
insert into x values (5,null);
304+
305+
create temp table y (y1 int, y2 int);
306+
insert into y values (1,111);
307+
insert into y values (2,222);
308+
insert into y values (3,333);
309+
insert into y values (4,null);
310+
311+
select * from x;
312+
select * from y;
313+
314+
select * from x left join y on (x1 = y1 and x2 is not null);
315+
select * from x left join y on (x1 = y1 and y2 is not null);
316+
317+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
318+
on (x1 = xx1);
319+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
320+
on (x1 = xx1 and x2 is not null);
321+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
322+
on (x1 = xx1 and y2 is not null);
323+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
324+
on (x1 = xx1 and xx2 is not null);
325+
-- these should NOT give the same answers as above
326+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
327+
on (x1 = xx1) where (x2 is not null);
328+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
329+
on (x1 = xx1) where (y2 is not null);
330+
select * from (x left join y on (x1 = y1)) left join x xx(xx1,xx2)
331+
on (x1 = xx1) where (xx2 is not null);
332+
333+
295334
--
296335
-- Clean up
297336
--

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