mirror of
https://github.com/postgres/postgres.git
synced 2025-05-19 00:04:06 -04:00
Avoid NullTest deduction for clone clauses
In commit b262ad440, we introduced an optimization that reduces an IS NOT NULL qual on a column defined as NOT NULL to constant true, and an IS NULL qual on a NOT NULL column to constant false, provided we can prove that the input expression of the NullTest is not nullable by any outer join. This deduction happens after we have generated multiple clones of the same qual condition to cope with commuted-left-join cases. However, performing the NullTest deduction for clone clauses can be unsafe, because we don't have a reliable way to determine if the input expression of a NullTest is non-nullable: nullingrel bits in clone clauses may not reflect reality, so we dare not draw conclusions from clones about whether Vars are guaranteed not-null. To fix, we check whether the given RestrictInfo is a clone clause in restriction_is_always_true and restriction_is_always_false, and avoid performing any reduction if it is. There are several ensuing plan changes in predicate.out, and we have to modify the tests to ensure that they continue to test what they are intended to. Additionally, this fix causes the test case added in f00ab1fd1 to no longer trigger the bug that commit fixed, so we also remove that test case. Back-patch to v17 where this bug crept in. Reported-by: Ronald Cruz <cruz@rentec.com> Diagnosed-by: Tom Lane <tgl@sss.pgh.pa.us> Author: Richard Guo <guofenglinux@gmail.com> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/f5320d3d-77af-4ce8-b9c3-4715ff33f213@rentec.com Backpatch-through: 17
This commit is contained in:
Richard Guo
parent
d6dd2a02ba
commit
bc5a08af3c
@ -2740,6 +2740,15 @@ bool
|
||||
restriction_is_always_true(PlannerInfo *root,
|
||||
RestrictInfo *restrictinfo)
|
||||
{
|
||||
/*
|
||||
* For a clone clause, we don't have a reliable way to determine if the
|
||||
* input expression of a NullTest is non-nullable: nullingrel bits in
|
||||
* clone clauses may not reflect reality, so we dare not draw conclusions
|
||||
* from clones about whether Vars are guaranteed not-null.
|
||||
*/
|
||||
if (restrictinfo->has_clone || restrictinfo->is_clone)
|
||||
return false;
|
||||
|
||||
/* Check for NullTest qual */
|
||||
if (IsA(restrictinfo->clause, NullTest))
|
||||
{
|
||||
@ -2789,6 +2798,15 @@ bool
|
||||
restriction_is_always_false(PlannerInfo *root,
|
||||
RestrictInfo *restrictinfo)
|
||||
{
|
||||
/*
|
||||
* For a clone clause, we don't have a reliable way to determine if the
|
||||
* input expression of a NullTest is non-nullable: nullingrel bits in
|
||||
* clone clauses may not reflect reality, so we dare not draw conclusions
|
||||
* from clones about whether Vars are guaranteed not-null.
|
||||
*/
|
||||
if (restrictinfo->has_clone || restrictinfo->is_clone)
|
||||
return false;
|
||||
|
||||
/* Check for NullTest qual */
|
||||
if (IsA(restrictinfo->clause, NullTest))
|
||||
{
|
||||
|
||||
@ -97,55 +97,50 @@ SELECT * FROM pred_tab t WHERE t.b IS NULL OR t.c IS NULL;
|
||||
-- and b) its Var is not nullable by any outer joins
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL;
|
||||
QUERY PLAN
|
||||
-------------------------------------------------
|
||||
LEFT JOIN pred_tab t2 ON t1.a IS NOT NULL;
|
||||
QUERY PLAN
|
||||
-------------------------------------
|
||||
Nested Loop Left Join
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Materialize
|
||||
-> Nested Loop Left Join
|
||||
-> Seq Scan on pred_tab t2
|
||||
-> Materialize
|
||||
-> Seq Scan on pred_tab t3
|
||||
(7 rows)
|
||||
-> Seq Scan on pred_tab t2
|
||||
(4 rows)
|
||||
|
||||
-- Ensure the IS_NOT_NULL qual is not ignored when columns are made nullable
|
||||
-- by an outer join
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON t1.a = 1
|
||||
FULL JOIN pred_tab t2 ON t1.a = t2.a
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL;
|
||||
QUERY PLAN
|
||||
-------------------------------------------
|
||||
Nested Loop Left Join
|
||||
Join Filter: (t2.a IS NOT NULL)
|
||||
-> Nested Loop Left Join
|
||||
Join Filter: (t1.a = 1)
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Materialize
|
||||
-> Merge Full Join
|
||||
Merge Cond: (t1.a = t2.a)
|
||||
-> Sort
|
||||
Sort Key: t1.a
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Sort
|
||||
Sort Key: t2.a
|
||||
-> Seq Scan on pred_tab t2
|
||||
-> Materialize
|
||||
-> Seq Scan on pred_tab t3
|
||||
(9 rows)
|
||||
(12 rows)
|
||||
|
||||
-- Ensure the IS_NULL qual is reduced to constant-FALSE, since a) it's on a NOT
|
||||
-- NULL column, and b) its Var is not nullable by any outer joins
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NULL AND t2.b = 1;
|
||||
QUERY PLAN
|
||||
---------------------------------------------------
|
||||
LEFT JOIN pred_tab t2 ON t1.a IS NULL;
|
||||
QUERY PLAN
|
||||
--------------------------------
|
||||
Nested Loop Left Join
|
||||
Join Filter: false
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Materialize
|
||||
-> Nested Loop Left Join
|
||||
Join Filter: (false AND (t2.b = 1))
|
||||
-> Seq Scan on pred_tab t2
|
||||
-> Result
|
||||
One-Time Filter: false
|
||||
(8 rows)
|
||||
-> Result
|
||||
One-Time Filter: false
|
||||
(5 rows)
|
||||
|
||||
-- Ensure the IS_NULL qual is not reduced to constant-FALSE when the column is
|
||||
-- nullable by an outer join
|
||||
@ -172,55 +167,50 @@ SELECT * FROM pred_tab t1
|
||||
-- Ensure the OR clause is ignored when an OR branch is provably always true
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL OR t2.b = 1;
|
||||
QUERY PLAN
|
||||
-------------------------------------------------
|
||||
LEFT JOIN pred_tab t2 ON t1.a IS NOT NULL OR t2.b = 1;
|
||||
QUERY PLAN
|
||||
-------------------------------------
|
||||
Nested Loop Left Join
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Materialize
|
||||
-> Nested Loop Left Join
|
||||
-> Seq Scan on pred_tab t2
|
||||
-> Materialize
|
||||
-> Seq Scan on pred_tab t3
|
||||
(7 rows)
|
||||
-> Seq Scan on pred_tab t2
|
||||
(4 rows)
|
||||
|
||||
-- Ensure the NullTest is not ignored when the column is nullable by an outer
|
||||
-- join
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON t1.a = 1
|
||||
FULL JOIN pred_tab t2 ON t1.a = t2.a
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL OR t2.b = 1;
|
||||
QUERY PLAN
|
||||
---------------------------------------------------
|
||||
Nested Loop Left Join
|
||||
Join Filter: ((t2.a IS NOT NULL) OR (t2.b = 1))
|
||||
-> Nested Loop Left Join
|
||||
Join Filter: (t1.a = 1)
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Materialize
|
||||
-> Merge Full Join
|
||||
Merge Cond: (t1.a = t2.a)
|
||||
-> Sort
|
||||
Sort Key: t1.a
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Sort
|
||||
Sort Key: t2.a
|
||||
-> Seq Scan on pred_tab t2
|
||||
-> Materialize
|
||||
-> Seq Scan on pred_tab t3
|
||||
(9 rows)
|
||||
(12 rows)
|
||||
|
||||
-- Ensure the OR clause is reduced to constant-FALSE when all OR branches are
|
||||
-- provably false
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab t3 ON (t2.a IS NULL OR t2.c IS NULL) AND t2.b = 1;
|
||||
QUERY PLAN
|
||||
---------------------------------------------------
|
||||
LEFT JOIN pred_tab t2 ON (t1.a IS NULL OR t1.c IS NULL);
|
||||
QUERY PLAN
|
||||
--------------------------------
|
||||
Nested Loop Left Join
|
||||
Join Filter: false
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Materialize
|
||||
-> Nested Loop Left Join
|
||||
Join Filter: (false AND (t2.b = 1))
|
||||
-> Seq Scan on pred_tab t2
|
||||
-> Result
|
||||
One-Time Filter: false
|
||||
(8 rows)
|
||||
-> Result
|
||||
One-Time Filter: false
|
||||
(5 rows)
|
||||
|
||||
-- Ensure the OR clause is not reduced to constant-FALSE when a column is
|
||||
-- made nullable from an outer join
|
||||
@ -290,3 +280,84 @@ SELECT * FROM pred_parent WHERE a IS NULL;
|
||||
(2 rows)
|
||||
|
||||
DROP TABLE pred_parent, pred_child;
|
||||
-- Validate we do not reduce a clone clause to a constant true or false
|
||||
CREATE TABLE pred_tab (a int, b int);
|
||||
CREATE TABLE pred_tab_notnull (a int, b int NOT NULL);
|
||||
INSERT INTO pred_tab VALUES (1, 1);
|
||||
INSERT INTO pred_tab VALUES (2, 2);
|
||||
INSERT INTO pred_tab_notnull VALUES (2, 2);
|
||||
INSERT INTO pred_tab_notnull VALUES (3, 3);
|
||||
ANALYZE pred_tab;
|
||||
ANALYZE pred_tab_notnull;
|
||||
-- Ensure the IS_NOT_NULL qual is not reduced to constant true and removed
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab_notnull t3 ON t2.a = t3.a
|
||||
LEFT JOIN pred_tab t4 ON t3.b IS NOT NULL;
|
||||
QUERY PLAN
|
||||
---------------------------------------------------------------
|
||||
Nested Loop Left Join
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Materialize
|
||||
-> Nested Loop Left Join
|
||||
Join Filter: (t3.b IS NOT NULL)
|
||||
-> Nested Loop Left Join
|
||||
Join Filter: (t2.a = t3.a)
|
||||
-> Seq Scan on pred_tab t2
|
||||
-> Materialize
|
||||
-> Seq Scan on pred_tab_notnull t3
|
||||
-> Materialize
|
||||
-> Seq Scan on pred_tab t4
|
||||
(12 rows)
|
||||
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab_notnull t3 ON t2.a = t3.a
|
||||
LEFT JOIN pred_tab t4 ON t3.b IS NOT NULL;
|
||||
a | b | a | b | a | b | a | b
|
||||
---+---+---+---+---+---+---+---
|
||||
1 | 1 | 1 | 1 | | | |
|
||||
1 | 1 | 2 | 2 | 2 | 2 | 1 | 1
|
||||
1 | 1 | 2 | 2 | 2 | 2 | 2 | 2
|
||||
2 | 2 | 1 | 1 | | | |
|
||||
2 | 2 | 2 | 2 | 2 | 2 | 1 | 1
|
||||
2 | 2 | 2 | 2 | 2 | 2 | 2 | 2
|
||||
(6 rows)
|
||||
|
||||
-- Ensure the IS_NULL qual is not reduced to constant false
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab_notnull t3 ON t2.a = t3.a
|
||||
LEFT JOIN pred_tab t4 ON t3.b IS NULL AND t3.a IS NOT NULL;
|
||||
QUERY PLAN
|
||||
--------------------------------------------------------------------
|
||||
Nested Loop Left Join
|
||||
-> Seq Scan on pred_tab t1
|
||||
-> Materialize
|
||||
-> Nested Loop Left Join
|
||||
Join Filter: ((t3.b IS NULL) AND (t3.a IS NOT NULL))
|
||||
-> Nested Loop Left Join
|
||||
Join Filter: (t2.a = t3.a)
|
||||
-> Seq Scan on pred_tab t2
|
||||
-> Materialize
|
||||
-> Seq Scan on pred_tab_notnull t3
|
||||
-> Materialize
|
||||
-> Seq Scan on pred_tab t4
|
||||
(12 rows)
|
||||
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab_notnull t3 ON t2.a = t3.a
|
||||
LEFT JOIN pred_tab t4 ON t3.b IS NULL AND t3.a IS NOT NULL;
|
||||
a | b | a | b | a | b | a | b
|
||||
---+---+---+---+---+---+---+---
|
||||
1 | 1 | 1 | 1 | | | |
|
||||
1 | 1 | 2 | 2 | 2 | 2 | |
|
||||
2 | 2 | 1 | 1 | | | |
|
||||
2 | 2 | 2 | 2 | 2 | 2 | |
|
||||
(4 rows)
|
||||
|
||||
DROP TABLE pred_tab;
|
||||
DROP TABLE pred_tab_notnull;
|
||||
|
||||
@ -64,22 +64,20 @@ SELECT * FROM pred_tab t WHERE t.b IS NULL OR t.c IS NULL;
|
||||
-- and b) its Var is not nullable by any outer joins
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL;
|
||||
LEFT JOIN pred_tab t2 ON t1.a IS NOT NULL;
|
||||
|
||||
-- Ensure the IS_NOT_NULL qual is not ignored when columns are made nullable
|
||||
-- by an outer join
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON t1.a = 1
|
||||
FULL JOIN pred_tab t2 ON t1.a = t2.a
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL;
|
||||
|
||||
-- Ensure the IS_NULL qual is reduced to constant-FALSE, since a) it's on a NOT
|
||||
-- NULL column, and b) its Var is not nullable by any outer joins
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NULL AND t2.b = 1;
|
||||
LEFT JOIN pred_tab t2 ON t1.a IS NULL;
|
||||
|
||||
-- Ensure the IS_NULL qual is not reduced to constant-FALSE when the column is
|
||||
-- nullable by an outer join
|
||||
@ -95,22 +93,20 @@ SELECT * FROM pred_tab t1
|
||||
-- Ensure the OR clause is ignored when an OR branch is provably always true
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL OR t2.b = 1;
|
||||
LEFT JOIN pred_tab t2 ON t1.a IS NOT NULL OR t2.b = 1;
|
||||
|
||||
-- Ensure the NullTest is not ignored when the column is nullable by an outer
|
||||
-- join
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON t1.a = 1
|
||||
FULL JOIN pred_tab t2 ON t1.a = t2.a
|
||||
LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL OR t2.b = 1;
|
||||
|
||||
-- Ensure the OR clause is reduced to constant-FALSE when all OR branches are
|
||||
-- provably false
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab t3 ON (t2.a IS NULL OR t2.c IS NULL) AND t2.b = 1;
|
||||
LEFT JOIN pred_tab t2 ON (t1.a IS NULL OR t1.c IS NULL);
|
||||
|
||||
-- Ensure the OR clause is not reduced to constant-FALSE when a column is
|
||||
-- made nullable from an outer join
|
||||
@ -147,3 +143,43 @@ EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_parent WHERE a IS NULL;
|
||||
|
||||
DROP TABLE pred_parent, pred_child;
|
||||
|
||||
-- Validate we do not reduce a clone clause to a constant true or false
|
||||
CREATE TABLE pred_tab (a int, b int);
|
||||
CREATE TABLE pred_tab_notnull (a int, b int NOT NULL);
|
||||
|
||||
INSERT INTO pred_tab VALUES (1, 1);
|
||||
INSERT INTO pred_tab VALUES (2, 2);
|
||||
|
||||
INSERT INTO pred_tab_notnull VALUES (2, 2);
|
||||
INSERT INTO pred_tab_notnull VALUES (3, 3);
|
||||
|
||||
ANALYZE pred_tab;
|
||||
ANALYZE pred_tab_notnull;
|
||||
|
||||
-- Ensure the IS_NOT_NULL qual is not reduced to constant true and removed
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab_notnull t3 ON t2.a = t3.a
|
||||
LEFT JOIN pred_tab t4 ON t3.b IS NOT NULL;
|
||||
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab_notnull t3 ON t2.a = t3.a
|
||||
LEFT JOIN pred_tab t4 ON t3.b IS NOT NULL;
|
||||
|
||||
-- Ensure the IS_NULL qual is not reduced to constant false
|
||||
EXPLAIN (COSTS OFF)
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab_notnull t3 ON t2.a = t3.a
|
||||
LEFT JOIN pred_tab t4 ON t3.b IS NULL AND t3.a IS NOT NULL;
|
||||
|
||||
SELECT * FROM pred_tab t1
|
||||
LEFT JOIN pred_tab t2 ON TRUE
|
||||
LEFT JOIN pred_tab_notnull t3 ON t2.a = t3.a
|
||||
LEFT JOIN pred_tab t4 ON t3.b IS NULL AND t3.a IS NOT NULL;
|
||||
|
||||
DROP TABLE pred_tab;
|
||||
DROP TABLE pred_tab_notnull;
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user