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3af7040985
b262ad440 added code to have the planner remove redundant IS NOT NULL
quals and eliminate needless scans for IS NULL quals on tables where the
qual's column has a NOT NULL constraint.
That commit failed to consider that an inheritance parent table could
have differing NOT NULL constraints between the parent and the child.
This caused issues as if we eliminated a qual on the parent, when
applying the quals to child tables in apply_child_basequals(), the qual
might not have been added to the parent's baserestrictinfo.
Here we fix this by not applying the optimization to remove redundant
quals to RelOptInfos belonging to inheritance parents and applying the
optimization again in apply_child_basequals(). Effectively, this means
that the parent and child are considered independently as the parent has
both an inh=true and inh=false RTE and we still apply the optimization
to the RelOptInfo corresponding to the inh=false RTE.
We're able to still apply the optimization in add_base_clause_to_rel()
for partitioned tables as the NULLability of partitions must match that
of their parent. And, if we ever expand restriction_is_always_false()
and restriction_is_always_true() to handle partition constraints then we
can apply the same logic as, even in multi-level partitioned tables,
there's no way to route values to a partition when the qual does not
match the partition qual of the partitioned table's parent partition.
The same is true for CHECK constraints as those must also match between
arent partitioned tables and their partitions.
Author: Richard Guo, David Rowley
Discussion: https://postgr.es/m/CAMbWs4930gQSZmjR7aANzEapdy61gCg6z8dT-kAEYD0sYWKPdQ@mail.gmail.com
150 lines
4.5 KiB
SQL
150 lines
4.5 KiB
SQL
--
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-- Tests for predicate handling
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--
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--
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-- Test that restrictions that are always true are ignored, and that are always
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-- false are replaced with constant-FALSE
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--
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-- Currently we only check for NullTest quals and OR clauses that include
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-- NullTest quals. We may extend it in the future.
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--
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CREATE TABLE pred_tab (a int NOT NULL, b int, c int NOT NULL);
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--
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-- Test restriction clauses
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--
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-- Ensure the IS_NOT_NULL qual is ignored when the column is non-nullable
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t WHERE t.a IS NOT NULL;
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-- Ensure the IS_NOT_NULL qual is not ignored on a nullable column
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t WHERE t.b IS NOT NULL;
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-- Ensure the IS_NULL qual is reduced to constant-FALSE for non-nullable
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-- columns
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t WHERE t.a IS NULL;
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-- Ensure the IS_NULL qual is not reduced to constant-FALSE on nullable
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-- columns
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t WHERE t.b IS NULL;
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--
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-- Tests for OR clauses in restriction clauses
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--
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-- Ensure the OR clause is ignored when an OR branch is always true
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t WHERE t.a IS NOT NULL OR t.b = 1;
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-- Ensure the OR clause is not ignored for NullTests that can't be proven
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-- always true
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t WHERE t.b IS NOT NULL OR t.a = 1;
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-- Ensure the OR clause is reduced to constant-FALSE when all branches are
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-- provably false
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t WHERE t.a IS NULL OR t.c IS NULL;
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-- Ensure the OR clause is not reduced to constant-FALSE when not all branches
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-- are provably false
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t WHERE t.b IS NULL OR t.c IS NULL;
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--
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-- Test join clauses
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--
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-- Ensure the IS_NOT_NULL qual is ignored, since a) it's on a NOT NULL column,
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-- and b) its Var is not nullable by any outer joins
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t1
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LEFT JOIN pred_tab t2 ON TRUE
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LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL;
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-- Ensure the IS_NOT_NULL qual is not ignored when columns are made nullable
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-- by an outer join
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t1
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LEFT JOIN pred_tab t2 ON t1.a = 1
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LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL;
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-- Ensure the IS_NULL qual is reduced to constant-FALSE, since a) it's on a NOT
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-- NULL column, and b) its Var is not nullable by any outer joins
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t1
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LEFT JOIN pred_tab t2 ON TRUE
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LEFT JOIN pred_tab t3 ON t2.a IS NULL AND t2.b = 1;
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-- Ensure the IS_NULL qual is not reduced to constant-FALSE when the column is
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-- nullable by an outer join
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t1
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LEFT JOIN pred_tab t2 ON t1.a = 1
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LEFT JOIN pred_tab t3 ON t2.a IS NULL;
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--
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-- Tests for OR clauses in join clauses
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--
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-- Ensure the OR clause is ignored when an OR branch is provably always true
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t1
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LEFT JOIN pred_tab t2 ON TRUE
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LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL OR t2.b = 1;
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-- Ensure the NullTest is not ignored when the column is nullable by an outer
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-- join
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t1
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LEFT JOIN pred_tab t2 ON t1.a = 1
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LEFT JOIN pred_tab t3 ON t2.a IS NOT NULL OR t2.b = 1;
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-- Ensure the OR clause is reduced to constant-FALSE when all OR branches are
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-- provably false
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t1
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LEFT JOIN pred_tab t2 ON TRUE
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LEFT JOIN pred_tab t3 ON (t2.a IS NULL OR t2.c IS NULL) AND t2.b = 1;
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-- Ensure the OR clause is not reduced to constant-FALSE when a column is
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-- made nullable from an outer join
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_tab t1
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LEFT JOIN pred_tab t2 ON t1.a = 1
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LEFT JOIN pred_tab t3 ON t2.a IS NULL OR t2.c IS NULL;
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DROP TABLE pred_tab;
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-- Validate we handle IS NULL and IS NOT NULL quals correctly with inheritance
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-- parents.
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CREATE TABLE pred_parent (a int);
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CREATE TABLE pred_child () INHERITS (pred_parent);
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ALTER TABLE ONLY pred_parent ALTER a SET NOT NULL;
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-- Ensure that the scan on pred_child contains the IS NOT NULL qual.
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_parent WHERE a IS NOT NULL;
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-- Ensure we only scan pred_child and not pred_parent
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_parent WHERE a IS NULL;
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ALTER TABLE pred_parent ALTER a DROP NOT NULL;
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ALTER TABLE pred_child ALTER a SET NOT NULL;
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-- Ensure the IS NOT NULL qual is removed from the pred_child scan.
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_parent WHERE a IS NOT NULL;
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-- Ensure we only scan pred_parent and not pred_child
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EXPLAIN (COSTS OFF)
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SELECT * FROM pred_parent WHERE a IS NULL;
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DROP TABLE pred_parent, pred_child;
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