Use the correct tuplestore read pointer in a NamedTuplestoreScan.

Tom Kazimiers reported that transition tables don't work correctly when
they are scanned by more than one executor node.  That's because commit
18ce3a4ab allocated separate read pointers for each executor node, as it
must, but failed to make them active at the appropriate times.  Repair.

Thomas Munro

Discussion: https://postgr.es/m/20180224034748.bixarv6632vbxgeb%40dewberry.localdomain

diff --git a/src/backend/executor/nodeNamedtuplestorescan.c b/src/backend/executor/nodeNamedtuplestorescan.c
index 4d898b1f83e3deea16d7b13f6a5f1e995c997813..b260ad25948a68d67d0c5cc2ebd6bb1d94ff7227 100644 (file)
--- a/src/backend/executor/nodeNamedtuplestorescan.c
+++ b/src/backend/executor/nodeNamedtuplestorescan.c
@@ -40,6 +40,7 @@ NamedTuplestoreScanNext(NamedTuplestoreScanState *node)
     * Get the next tuple from tuplestore. Return NULL if no more tuples.
     */
    slot = node->ss.ss_ScanTupleSlot;
+   tuplestore_select_read_pointer(node->relation, node->readptr);
    (void) tuplestore_gettupleslot(node->relation, true, false, slot);
    return slot;
 }
@@ -116,6 +117,7 @@ ExecInitNamedTuplestoreScan(NamedTuplestoreScan *node, EState *estate, int eflag
     * The new read pointer copies its position from read pointer 0, which
     * could be anywhere, so explicitly rewind it.
     */
+   tuplestore_select_read_pointer(scanstate->relation, scanstate->readptr);
    tuplestore_rescan(scanstate->relation);
 
    /*

diff --git a/src/test/regress/expected/plpgsql.out b/src/test/regress/expected/plpgsql.out
index d294e5363455704e4097d692121321a83f783e06..722715049c9260f6ed5c6b90eb0f3f391dbe4db2 100644 (file)
--- a/src/test/regress/expected/plpgsql.out
+++ b/src/test/regress/expected/plpgsql.out
@@ -5559,6 +5559,28 @@ LINE 1: SELECT (SELECT string_agg(id || '=' || name, ',') FROM d)
 QUERY:  SELECT (SELECT string_agg(id || '=' || name, ',') FROM d)
 CONTEXT:  PL/pgSQL function alter_table_under_transition_tables_upd_func() line 3 at RAISE
 --
+-- Test multiple reference to a transition table
+--
+CREATE TABLE multi_test (i int);
+INSERT INTO multi_test VALUES (1);
+CREATE OR REPLACE FUNCTION multi_test_trig() RETURNS trigger
+LANGUAGE plpgsql AS $$
+BEGIN
+    RAISE NOTICE 'count = %', (SELECT COUNT(*) FROM new_test);
+    RAISE NOTICE 'count union = %',
+      (SELECT COUNT(*)
+       FROM (SELECT * FROM new_test UNION ALL SELECT * FROM new_test) ss);
+    RETURN NULL;
+END$$;
+CREATE TRIGGER my_trigger AFTER UPDATE ON multi_test
+  REFERENCING NEW TABLE AS new_test OLD TABLE as old_test
+  FOR EACH STATEMENT EXECUTE PROCEDURE multi_test_trig();
+UPDATE multi_test SET i = i;
+NOTICE:  count = 1
+NOTICE:  count union = 2
+DROP TABLE multi_test;
+DROP FUNCTION multi_test_trig();
+--
 -- Check type parsing and record fetching from partitioned tables
 --
 CREATE TABLE partitioned_table (a int, b text) PARTITION BY LIST (a);

diff --git a/src/test/regress/sql/plpgsql.sql b/src/test/regress/sql/plpgsql.sql
index f17cf0b49bf60ce4d457d760dd6b668d8cacd984..f405d157bba61b11d391874953467fa14e003fff 100644 (file)
--- a/src/test/regress/sql/plpgsql.sql
+++ b/src/test/regress/sql/plpgsql.sql
@@ -4503,6 +4503,32 @@ ALTER TABLE alter_table_under_transition_tables
 UPDATE alter_table_under_transition_tables
   SET id = id;
 
+--
+-- Test multiple reference to a transition table
+--
+
+CREATE TABLE multi_test (i int);
+INSERT INTO multi_test VALUES (1);
+
+CREATE OR REPLACE FUNCTION multi_test_trig() RETURNS trigger
+LANGUAGE plpgsql AS $$
+BEGIN
+    RAISE NOTICE 'count = %', (SELECT COUNT(*) FROM new_test);
+    RAISE NOTICE 'count union = %',
+      (SELECT COUNT(*)
+       FROM (SELECT * FROM new_test UNION ALL SELECT * FROM new_test) ss);
+    RETURN NULL;
+END$$;
+
+CREATE TRIGGER my_trigger AFTER UPDATE ON multi_test
+  REFERENCING NEW TABLE AS new_test OLD TABLE as old_test
+  FOR EACH STATEMENT EXECUTE PROCEDURE multi_test_trig();
+
+UPDATE multi_test SET i = i;
+
+DROP TABLE multi_test;
+DROP FUNCTION multi_test_trig();
+
 --
 -- Check type parsing and record fetching from partitioned tables
 --