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

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

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index a06e5edf6dbbc3c8d1505f67cbbc6f1ea149ba6c..80ad6bf1741c0f07965d99b478a5371893299ec6 100644 (file)
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -6695,18 +6695,10 @@ 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 b6e9a35d9c59f512eb7f217d4492e59da52fd0e8..60978f9415b33d1dd125ee76336ca57c619a09e2 100644 (file)
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -3504,74 +3504,6 @@ 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 7ca3bb3b1222251be9d77c286c196e7d9d1934b6..4f5418b9728fdbb852ed0bc1690b9a80c20a20eb 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 cd94a636f7da6d2985b7bd77e40cd3c03213a0c2..93ed5e8cc00ea08463cb46840c7628c37ce27e82 100644 (file)
--- a/src/test/regress/expected/btree_index.out
+++ b/src/test/regress/expected/btree_index.out
@@ -387,22 +387,3 @@ 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 91934be48a1d9758ead0d72aa2e3faba7c1b0b70..239f4a4755f042832a55e44a030f893e29a10245 100644 (file)
--- a/src/test/regress/sql/btree_index.sql
+++ b/src/test/regress/sql/btree_index.sql
@@ -242,25 +242,3 @@ 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;