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 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;