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Commit 099ca50

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michaelpqmichaelpq
committed
Revert "Fix parallel-safety check of expressions and predicate for index builds"
This reverts commit eae7be6, following a discussion with Tom Lane, due to concerns that this impacts the decisions made by the planner for the number of workers spawned based on the inlining and const-folding of index expressions and predicate for cases that would have worked until this commit. Discussion: https://postgr.es/m/162802.1709746091@sss.pgh.pa.us Backpatch-through: 12
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‎src/backend/optimizer/plan/planner.c

Copy file name to clipboardExpand all lines: src/backend/optimizer/plan/planner.c
+2-10Lines changed: 2 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -6667,18 +6667,10 @@ plan_create_index_workers(Oid tableOid, Oid indexOid)
66676667
* Currently, parallel workers can't access the leader's temporary tables.
66686668
* Furthermore, any index predicate or index expressions must be parallel
66696669
* safe.
6670-
*
6671-
* Fetch the list of expressions and predicates directly from the
6672-
* catalogs. Retrieving this information from the relcache would cause
6673-
* the expressions and predicates to be flattened, losing properties that
6674-
* can be important to check if parallel workers can be used. For
6675-
* example, immutable parallel-unsafe functions, that cannot be used in
6676-
* parallel workers, would be changed to Const nodes, that are safe in
6677-
* parallel workers.
66786670
*/
66796671
if (heap->rd_rel->relpersistence == RELPERSISTENCE_TEMP ||
6680-
!is_parallel_safe(root, (Node *) get_index_expressions(indexOid)) ||
6681-
!is_parallel_safe(root, (Node *) get_index_predicate(indexOid)))
6672+
!is_parallel_safe(root, (Node *) RelationGetIndexExpressions(index)) ||
6673+
!is_parallel_safe(root, (Node *) RelationGetIndexPredicate(index)))
66826674
{
66836675
parallel_workers = 0;
66846676
goto done;

‎src/backend/utils/cache/lsyscache.c

Copy file name to clipboardExpand all lines: src/backend/utils/cache/lsyscache.c
-68Lines changed: 0 additions & 68 deletions
Original file line numberDiff line numberDiff line change
@@ -3502,74 +3502,6 @@ get_index_column_opclass(Oid index_oid, int attno)
35023502
return opclass;
35033503
}
35043504

3505-
/*
3506-
* get_index_expressions
3507-
*
3508-
* Given the index OID, its a List of its expressions or NIL if none.
3509-
*/
3510-
List *
3511-
get_index_expressions(Oid index_oid)
3512-
{
3513-
List *result;
3514-
HeapTuple tuple;
3515-
Datum exprDatum;
3516-
bool isnull;
3517-
char *exprString;
3518-
3519-
tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));
3520-
if (!HeapTupleIsValid(tuple))
3521-
elog(ERROR, "cache lookup failed for index %u", index_oid);
3522-
3523-
exprDatum = SysCacheGetAttr(INDEXRELID, tuple,
3524-
Anum_pg_index_indexprs, &isnull);
3525-
if (isnull)
3526-
{
3527-
ReleaseSysCache(tuple);
3528-
return NIL;
3529-
}
3530-
3531-
exprString = TextDatumGetCString(exprDatum);
3532-
result = (List *) stringToNode(exprString);
3533-
pfree(exprString);
3534-
ReleaseSysCache(tuple);
3535-
3536-
return result;
3537-
}
3538-
3539-
/*
3540-
* get_index_predicate
3541-
*
3542-
* Given the index OID, return a List of its predicate or NIL if none.
3543-
*/
3544-
List *
3545-
get_index_predicate(Oid index_oid)
3546-
{
3547-
List *result;
3548-
HeapTuple tuple;
3549-
Datum predDatum;
3550-
bool isnull;
3551-
char *predString;
3552-
3553-
tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));
3554-
if (!HeapTupleIsValid(tuple))
3555-
elog(ERROR, "cache lookup failed for index %u", index_oid);
3556-
3557-
predDatum = SysCacheGetAttr(INDEXRELID, tuple,
3558-
Anum_pg_index_indpred, &isnull);
3559-
if (isnull)
3560-
{
3561-
ReleaseSysCache(tuple);
3562-
return NIL;
3563-
}
3564-
3565-
predString = TextDatumGetCString(predDatum);
3566-
result = (List *) stringToNode(predString);
3567-
pfree(predString);
3568-
ReleaseSysCache(tuple);
3569-
3570-
return result;
3571-
}
3572-
35733505
/*
35743506
* get_index_isreplident
35753507
*

‎src/include/utils/lsyscache.h

Copy file name to clipboardExpand all lines: src/include/utils/lsyscache.h
-2Lines changed: 0 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -195,8 +195,6 @@ extern Oid get_range_collation(Oid rangeOid);
195195
extern Oid get_range_multirange(Oid rangeOid);
196196
extern Oid get_multirange_range(Oid multirangeOid);
197197
extern Oid get_index_column_opclass(Oid index_oid, int attno);
198-
extern List *get_index_expressions(Oid index_oid);
199-
extern List *get_index_predicate(Oid index_oid);
200198
extern bool get_index_isreplident(Oid index_oid);
201199
extern bool get_index_isvalid(Oid index_oid);
202200
extern bool get_index_isclustered(Oid index_oid);

‎src/test/regress/expected/btree_index.out

Copy file name to clipboardExpand all lines: src/test/regress/expected/btree_index.out
-19Lines changed: 0 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -434,22 +434,3 @@ ALTER INDEX btree_part_idx ALTER COLUMN id SET (n_distinct=100);
434434
ERROR: ALTER action ALTER COLUMN ... SET cannot be performed on relation "btree_part_idx"
435435
DETAIL: This operation is not supported for partitioned indexes.
436436
DROP TABLE btree_part;
437-
-- Test with index expression and predicate that include a parallel unsafe
438-
-- function.
439-
CREATE FUNCTION para_unsafe_f() RETURNS int IMMUTABLE PARALLEL UNSAFE
440-
AS $$
441-
BEGIN
442-
RETURN 0;
443-
EXCEPTION WHEN OTHERS THEN
444-
RETURN 1;
445-
END$$ LANGUAGE plpgsql;
446-
CREATE TABLE btree_para_bld(i int);
447-
ALTER TABLE btree_para_bld SET (parallel_workers = 4);
448-
SET max_parallel_maintenance_workers TO 4;
449-
-- With parallel-unsafe expression
450-
CREATE INDEX ON btree_para_bld((i + para_unsafe_f()));
451-
-- With parallel-unsafe predicate
452-
CREATE INDEX ON btree_para_bld(i) WHERE i > para_unsafe_f();
453-
RESET max_parallel_maintenance_workers;
454-
DROP TABLE btree_para_bld;
455-
DROP FUNCTION para_unsafe_f;

‎src/test/regress/sql/btree_index.sql

Copy file name to clipboardExpand all lines: src/test/regress/sql/btree_index.sql
-22Lines changed: 0 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -267,25 +267,3 @@ CREATE TABLE btree_part (id int4) PARTITION BY RANGE (id);
267267
CREATE INDEX btree_part_idx ON btree_part(id);
268268
ALTER INDEX btree_part_idx ALTER COLUMN id SET (n_distinct=100);
269269
DROP TABLE btree_part;
270-
271-
-- Test with index expression and predicate that include a parallel unsafe
272-
-- function.
273-
CREATE FUNCTION para_unsafe_f() RETURNS int IMMUTABLE PARALLEL UNSAFE
274-
AS $$
275-
BEGIN
276-
RETURN 0;
277-
EXCEPTION WHEN OTHERS THEN
278-
RETURN 1;
279-
END$$ LANGUAGE plpgsql;
280-
281-
CREATE TABLE btree_para_bld(i int);
282-
ALTER TABLE btree_para_bld SET (parallel_workers = 4);
283-
SET max_parallel_maintenance_workers TO 4;
284-
-- With parallel-unsafe expression
285-
CREATE INDEX ON btree_para_bld((i + para_unsafe_f()));
286-
-- With parallel-unsafe predicate
287-
CREATE INDEX ON btree_para_bld(i) WHERE i > para_unsafe_f();
288-
289-
RESET max_parallel_maintenance_workers;
290-
DROP TABLE btree_para_bld;
291-
DROP FUNCTION para_unsafe_f;

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