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Revert "Fix parallel-safety check of expressions and predicate for index builds"

author Michael Paquier <michael@paquier.xyz>

Wed, 6 Mar 2024 23:30:35 +0000 (08:30 +0900)

committer Michael Paquier <michael@paquier.xyz>

Wed, 6 Mar 2024 23:30:35 +0000 (08:30 +0900)

This reverts commit eae7be600be7, 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

src/backend/optimizer/plan/planner.c patch | blob | blame | history

src/backend/utils/cache/lsyscache.c patch | blob | blame | history

src/include/utils/lsyscache.h patch | blob | blame | history

src/test/regress/expected/btree_index.out patch | blob | blame | history

src/test/regress/sql/btree_index.sql patch | blob | blame | history

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c

index d1552fb5eab68519acede72a0f25746b271e30a9..443ab08d75ab57bfd8849d43112bf926fabfbb2b 100644 (file)

--- a/src/backend/optimizer/plan/planner.c

+++ b/src/backend/optimizer/plan/planner.c

@@ -6667,18 +6667,10 @@ plan_create_index_workers(Oid tableOid, Oid indexOid)

* Currently, parallel workers can't access the leader's temporary tables.

* Furthermore, any index predicate or index expressions must be parallel

* safe.

- *

- * Fetch the list of expressions and predicates directly from the

- * catalogs. Retrieving this information from the relcache would cause

- * the expressions and predicates to be flattened, losing properties that

- * can be important to check if parallel workers can be used. For

- * example, immutable parallel-unsafe functions, that cannot be used in

- * parallel workers, would be changed to Const nodes, that are safe in

- * parallel workers.

if (heap->rd_rel->relpersistence == RELPERSISTENCE_TEMP ||

- !is_parallel_safe(root, (Node *) get_index_expressions(indexOid)) ||

- !is_parallel_safe(root, (Node *) get_index_predicate(indexOid)))

+ !is_parallel_safe(root, (Node *) RelationGetIndexExpressions(index)) ||

+ !is_parallel_safe(root, (Node *) RelationGetIndexPredicate(index)))

{

parallel_workers = 0;

goto done;

diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c

index 3fbae06de9b970f64db60fba7c8d64d69fb7afa2..6418d1c6ebade9db22ed92e99f3d2b5b8ad96257 100644 (file)

--- a/src/backend/utils/cache/lsyscache.c

+++ b/src/backend/utils/cache/lsyscache.c

@@ -3502,74 +3502,6 @@ get_index_column_opclass(Oid index_oid, int attno)

return opclass;

}

-/*

- * get_index_expressions

- *

- * Given the index OID, its a List of its expressions or NIL if none.

- */

-List *

-get_index_expressions(Oid index_oid)

- List *result;

- HeapTuple tuple;

- Datum exprDatum;

- bool isnull;

- char *exprString;

- tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));

- if (!HeapTupleIsValid(tuple))

- elog(ERROR, "cache lookup failed for index %u", index_oid);

- exprDatum = SysCacheGetAttr(INDEXRELID, tuple,

- Anum_pg_index_indexprs, &isnull);

- if (isnull)

- {

- ReleaseSysCache(tuple);

- return NIL;

- }

- exprString = TextDatumGetCString(exprDatum);

- result = (List *) stringToNode(exprString);

- pfree(exprString);

- ReleaseSysCache(tuple);

- return result;

-/*

- * get_index_predicate

- *

- * Given the index OID, return a List of its predicate or NIL if none.

- */

-List *

-get_index_predicate(Oid index_oid)

- List *result;

- HeapTuple tuple;

- Datum predDatum;

- bool isnull;

- char *predString;

- tuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(index_oid));

- if (!HeapTupleIsValid(tuple))

- elog(ERROR, "cache lookup failed for index %u", index_oid);

- predDatum = SysCacheGetAttr(INDEXRELID, tuple,

- Anum_pg_index_indpred, &isnull);

- if (isnull)

- {

- ReleaseSysCache(tuple);

- return NIL;

- }

- predString = TextDatumGetCString(predDatum);

- result = (List *) stringToNode(predString);

- pfree(predString);

- ReleaseSysCache(tuple);

- return result;

* get_index_isreplident

diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h

index 62a0d576f5758447c27fcb37794de1790c344e64..e4a200b00ec9c15030cdadee53c25a74dacb79bf 100644 (file)

--- a/src/include/utils/lsyscache.h

+++ b/src/include/utils/lsyscache.h

@@ -195,8 +195,6 @@ extern Oid get_range_collation(Oid rangeOid);

extern Oid get_range_multirange(Oid rangeOid);

extern Oid get_multirange_range(Oid multirangeOid);

extern Oid get_index_column_opclass(Oid index_oid, int attno);

-extern List *get_index_expressions(Oid index_oid);

-extern List *get_index_predicate(Oid index_oid);

extern bool get_index_isreplident(Oid index_oid);

extern bool get_index_isvalid(Oid index_oid);

extern bool get_index_isclustered(Oid index_oid);

diff --git a/src/test/regress/expected/btree_index.out b/src/test/regress/expected/btree_index.out

index ca4ef0d72c6c26cf0c67f79bb2a7e8c3b01c7eb8..8311a03c3df984d51dfc47d3d14adf8c09aacf42 100644 (file)

--- a/src/test/regress/expected/btree_index.out

+++ b/src/test/regress/expected/btree_index.out

@@ -434,22 +434,3 @@ ALTER INDEX btree_part_idx ALTER COLUMN id SET (n_distinct=100);

ERROR: ALTER action ALTER COLUMN ... SET cannot be performed on relation "btree_part_idx"

DETAIL: This operation is not supported for partitioned indexes.

DROP TABLE btree_part;

--- Test with index expression and predicate that include a parallel unsafe

--- function.

-CREATE FUNCTION para_unsafe_f() RETURNS int IMMUTABLE PARALLEL UNSAFE

-AS $$

-BEGIN

- RETURN 0;

-EXCEPTION WHEN OTHERS THEN

- RETURN 1;

-END$$ LANGUAGE plpgsql;

-CREATE TABLE btree_para_bld(i int);

-ALTER TABLE btree_para_bld SET (parallel_workers = 4);

-SET max_parallel_maintenance_workers TO 4;

--- With parallel-unsafe expression

-CREATE INDEX ON btree_para_bld((i + para_unsafe_f()));

--- With parallel-unsafe predicate

-CREATE INDEX ON btree_para_bld(i) WHERE i > para_unsafe_f();

-RESET max_parallel_maintenance_workers;

-DROP TABLE btree_para_bld;

-DROP FUNCTION para_unsafe_f;

diff --git a/src/test/regress/sql/btree_index.sql b/src/test/regress/sql/btree_index.sql

index a916e660c34048bbddfa9df822e6328665df9391..ef8435423472d6ff4100a0d73ad1e21d75fbd113 100644 (file)

--- a/src/test/regress/sql/btree_index.sql

+++ b/src/test/regress/sql/btree_index.sql

@@ -267,25 +267,3 @@ CREATE TABLE btree_part (id int4) PARTITION BY RANGE (id);

CREATE INDEX btree_part_idx ON btree_part(id);

ALTER INDEX btree_part_idx ALTER COLUMN id SET (n_distinct=100);

DROP TABLE btree_part;

--- Test with index expression and predicate that include a parallel unsafe

--- function.

-CREATE FUNCTION para_unsafe_f() RETURNS int IMMUTABLE PARALLEL UNSAFE

-AS $$

-BEGIN

- RETURN 0;

-EXCEPTION WHEN OTHERS THEN

- RETURN 1;

-END$$ LANGUAGE plpgsql;

-CREATE TABLE btree_para_bld(i int);

-ALTER TABLE btree_para_bld SET (parallel_workers = 4);

-SET max_parallel_maintenance_workers TO 4;

--- With parallel-unsafe expression

-CREATE INDEX ON btree_para_bld((i + para_unsafe_f()));

--- With parallel-unsafe predicate

-CREATE INDEX ON btree_para_bld(i) WHERE i > para_unsafe_f();

-RESET max_parallel_maintenance_workers;

-DROP TABLE btree_para_bld;

-DROP FUNCTION para_unsafe_f;

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