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--
-- Tests for predicate handling
--
--
-- Test that restrictions that are always true are ignored, and that are always
-- false are replaced with constant-FALSE
--
-- Currently we only check for NullTest quals and OR clauses that include
-- NullTest quals. We may extend it in the future.
--
CREATE TABLE pred_tab (a int NOT NULL, b int, c int NOT NULL);
--
-- Test restriction clauses
--
-- Ensure the IS_NOT_NULL qual is ignored when the column is non-nullable
EXPLAIN (COSTS OFF)
SELECT * FROM pred_tab t WHERE t.a IS NOT NULL;
-- Ensure the IS_NOT_NULL qual is not ignored on a nullable column
EXPLAIN (COSTS OFF)
SELECT * FROM pred_tab t WHERE t.b IS NOT NULL;
-- Ensure the IS_NULL qual is reduced to constant-FALSE for non-nullable
-- columns
EXPLAIN (COSTS OFF)
SELECT * FROM pred_tab t WHERE t.a IS NULL;
-- Ensure the IS_NULL qual is not reduced to constant-FALSE on nullable
-- columns
EXPLAIN (COSTS OFF)
SELECT * FROM pred_tab t WHERE t.b IS NULL;
--
-- Tests for OR clauses in restriction clauses
--
-- Ensure the OR clause is ignored when an OR branch is always true
EXPLAIN (COSTS OFF)
SELECT * FROM pred_tab t WHERE t.a IS NOT NULL OR t.b = 1;
-- Ensure the OR clause is not ignored for NullTests that can't be proven
-- always true
EXPLAIN (COSTS OFF)
SELECT * FROM pred_tab t WHERE t.b IS NOT NULL OR t.a = 1;
-- Ensure the OR clause is reduced to constant-FALSE when all branches are
-- provably false
EXPLAIN (COSTS OFF)
SELECT * FROM pred_tab t WHERE t.a IS NULL OR t.c IS NULL;
-- Ensure the OR clause is not reduced to constant-FALSE when not all branches
-- are provably false
EXPLAIN (COSTS OFF)
SELECT * FROM pred_tab t WHERE t.b IS NULL OR t.c IS NULL;
--
-- Test join clauses
--
-- Ensure the IS_NOT_NULL qual is ignored, 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 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
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;
-- Ensure the IS_NULL qual is not reduced to constant-FALSE 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
LEFT JOIN pred_tab t3 ON t2.a IS NULL;
--
-- Tests for OR clauses in join clauses
--
-- 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;
-- 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
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;
-- Ensure the OR clause is not reduced to constant-FALSE when a column is
-- made nullable from an outer join
EXPLAIN (COSTS OFF)
SELECT * FROM pred_tab t1
LEFT JOIN pred_tab t2 ON t1.a = 1
LEFT JOIN pred_tab t3 ON t2.a IS NULL OR t2.c IS NULL;
DROP TABLE pred_tab;
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