Calculate extraUpdatedCols in query rewriter, not parser.

It's unsafe to do this at parse time because addition of generated
columns to a table would not invalidate stored rules containing
UPDATEs on the table ... but there might now be dependent generated
columns that were not there when the rule was made.  This also fixes
an oversight that rewriteTargetView failed to update extraUpdatedCols
when transforming an UPDATE on an updatable view.  (Since the new
calculation is downstream of that, rewriteTargetView doesn't actually
need to do anything; but before, there was a demonstrable bug there.)

In v13 and HEAD, this leads to easily-visible bugs because (since
commit c6679e4f) we won't recalculate generated columns that aren't
listed in extraUpdatedCols.  In v12 this bitmap is mostly just used
for trigger-firing decisions, so you'd only notice a problem if a
trigger cared whether a generated column had been updated.

I'd complained about this back in May, but then forgot about it
until bug #16671 from Michael Paul Killian revived the issue.

Back-patch to v12 where this field was introduced.  If existing
stored rules contain any extraUpdatedCols values, they'll be
ignored because the rewriter will overwrite them, so the bug will
be fixed even for existing rules.  (But note that if someone were
to update to 13.1 or 12.5, store some rules with UPDATEs on tables
having generated columns, and then downgrade to a prior minor version,
they might observe issues similar to what this patch fixes.  That
seems unlikely enough to not be worth going to a lot of effort to fix.)

Discussion: https://postgr.es/m/10206.1588964727@sss.pgh.pa.us
Discussion: https://postgr.es/m/16671-2fa55851859fb166@postgresql.org

src/backend/optimizer/plan/setrefs.c

@@ -438,9 +438,9 @@ flatten_rtes_walker(Node *node, PlannerGlobal *glob)
  * In the flat rangetable, we zero out substructure pointers that are not
  * needed by the executor; this reduces the storage space and copying cost
  * for cached plans.  We keep only the ctename, alias and eref Alias fields,
- * which are needed by EXPLAIN, and the selectedCols, insertedCols and
- * updatedCols bitmaps, which are needed for executor-startup permissions
- * checking and for trigger event checking.
+ * which are needed by EXPLAIN, and the selectedCols, insertedCols,
+ * updatedCols, and extraUpdatedCols bitmaps, which are needed for
+ * executor-startup permissions checking and for trigger event checking.
  */
 static void
 add_rte_to_flat_rtable(PlannerGlobal *glob, RangeTblEntry *rte)

src/backend/parser/analyze.c

@@ -2282,7 +2282,6 @@ transformUpdateTargetList(ParseState *pstate, List *origTlist)
 	RangeTblEntry *target_rte;
 	ListCell   *orig_tl;
 	ListCell   *tl;
-	TupleDesc	tupdesc = pstate->p_target_relation->rd_att;
 
 	tlist = transformTargetList(pstate, origTlist,
 								EXPR_KIND_UPDATE_SOURCE);
@@ -2341,41 +2340,9 @@ transformUpdateTargetList(ParseState *pstate, List *origTlist)
 	if (orig_tl != NULL)
 		elog(ERROR, "UPDATE target count mismatch --- internal error");
 
-	fill_extraUpdatedCols(target_rte, tupdesc);
-
 	return tlist;
 }
 
-/*
- * Record in extraUpdatedCols generated columns referencing updated base
- * columns.
- */
-void
-fill_extraUpdatedCols(RangeTblEntry *target_rte, TupleDesc tupdesc)
-{
-	if (tupdesc->constr &&
-		tupdesc->constr->has_generated_stored)
-	{
-		for (int i = 0; i < tupdesc->constr->num_defval; i++)
-		{
-			AttrDefault defval = tupdesc->constr->defval[i];
-			Node	   *expr;
-			Bitmapset  *attrs_used = NULL;
-
-			/* skip if not generated column */
-			if (!TupleDescAttr(tupdesc, defval.adnum - 1)->attgenerated)
-				continue;
-
-			expr = stringToNode(defval.adbin);
-			pull_varattnos(expr, 1, &attrs_used);
-
-			if (bms_overlap(target_rte->updatedCols, attrs_used))
-				target_rte->extraUpdatedCols = bms_add_member(target_rte->extraUpdatedCols,
-															  defval.adnum - FirstLowInvalidHeapAttributeNumber);
-		}
-	}
-}
-
 /*
  * transformReturningList -
  *	handle a RETURNING clause in INSERT/UPDATE/DELETE

src/backend/replication/logical/worker.c

@@ -81,8 +81,6 @@
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "optimizer/optimizer.h"
-#include "parser/analyze.h"
-#include "parser/parse_relation.h"
 #include "pgstat.h"
 #include "postmaster/bgworker.h"
 #include "postmaster/interrupt.h"
@@ -1323,7 +1321,8 @@ apply_handle_update(StringInfo s)
 		}
 	}
 
-	fill_extraUpdatedCols(target_rte, RelationGetDescr(rel->localrel));
+	/* Also populate extraUpdatedCols, in case we have generated columns */
+	fill_extraUpdatedCols(target_rte, rel->localrel);
 
 	PushActiveSnapshot(GetTransactionSnapshot());
 

src/backend/rewrite/rewriteHandler.c

@@ -30,6 +30,7 @@
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
+#include "optimizer/optimizer.h"
 #include "parser/analyze.h"
 #include "parser/parse_coerce.h"
 #include "parser/parse_relation.h"
@@ -1508,6 +1509,42 @@ rewriteTargetListUD(Query *parsetree, RangeTblEntry *target_rte,
 	}
 }
 
+/*
+ * Record in target_rte->extraUpdatedCols the indexes of any generated columns
+ * that depend on any columns mentioned in target_rte->updatedCols.
+ */
+void
+fill_extraUpdatedCols(RangeTblEntry *target_rte, Relation target_relation)
+{
+	TupleDesc	tupdesc = RelationGetDescr(target_relation);
+	TupleConstr *constr = tupdesc->constr;
+
+	target_rte->extraUpdatedCols = NULL;
+
+	if (constr && constr->has_generated_stored)
+	{
+		for (int i = 0; i < constr->num_defval; i++)
+		{
+			AttrDefault *defval = &constr->defval[i];
+			Node	   *expr;
+			Bitmapset  *attrs_used = NULL;
+
+			/* skip if not generated column */
+			if (!TupleDescAttr(tupdesc, defval->adnum - 1)->attgenerated)
+				continue;
+
+			/* identify columns this generated column depends on */
+			expr = stringToNode(defval->adbin);
+			pull_varattnos(expr, 1, &attrs_used);
+
+			if (bms_overlap(target_rte->updatedCols, attrs_used))
+				target_rte->extraUpdatedCols =
+					bms_add_member(target_rte->extraUpdatedCols,
+								   defval->adnum - FirstLowInvalidHeapAttributeNumber);
+		}
+	}
+}
+
 
 /*
  * matchLocks -
@@ -1639,6 +1676,7 @@ ApplyRetrieveRule(Query *parsetree,
 			rte->selectedCols = NULL;
 			rte->insertedCols = NULL;
 			rte->updatedCols = NULL;
+			rte->extraUpdatedCols = NULL;
 
 			/*
 			 * For the most part, Vars referencing the view should remain as
@@ -3617,6 +3655,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 									parsetree->override,
 									rt_entry_relation,
 									parsetree->resultRelation);
+
+			/* Also populate extraUpdatedCols (for generated columns) */
+			fill_extraUpdatedCols(rt_entry, rt_entry_relation);
 		}
 		else if (event == CMD_DELETE)
 		{

src/include/nodes/parsenodes.h

@@ -940,12 +940,16 @@ typedef struct PartitionCmd
  *
  *	  updatedCols is also used in some other places, for example, to determine
  *	  which triggers to fire and in FDWs to know which changed columns they
- *	  need to ship off.  Generated columns that are caused to be updated by an
- *	  update to a base column are collected in extraUpdatedCols.  This is not
- *	  considered for permission checking, but it is useful in those places
- *	  that want to know the full set of columns being updated as opposed to
- *	  only the ones the user explicitly mentioned in the query.  (There is
- *	  currently no need for an extraInsertedCols, but it could exist.)
+ *	  need to ship off.
+ *
+ *	  Generated columns that are caused to be updated by an update to a base
+ *	  column are listed in extraUpdatedCols.  This is not considered for
+ *	  permission checking, but it is useful in those places that want to know
+ *	  the full set of columns being updated as opposed to only the ones the
+ *	  user explicitly mentioned in the query.  (There is currently no need for
+ *	  an extraInsertedCols, but it could exist.)  Note that extraUpdatedCols
+ *	  is populated during query rewrite, NOT in the parser, since generated
+ *	  columns could be added after a rule has been parsed and stored.
  *
  *	  securityQuals is a list of security barrier quals (boolean expressions),
  *	  to be tested in the listed order before returning a row from the

src/include/parser/analyze.h

@@ -46,6 +46,4 @@ extern void applyLockingClause(Query *qry, Index rtindex,
 extern List *BuildOnConflictExcludedTargetlist(Relation targetrel,
 											   Index exclRelIndex);
 
-extern void fill_extraUpdatedCols(RangeTblEntry *target_rte, TupleDesc tupdesc);
-
 #endif							/* ANALYZE_H */

src/include/rewrite/rewriteHandler.h

@@ -26,6 +26,9 @@ extern Node *build_column_default(Relation rel, int attrno);
 extern void rewriteTargetListUD(Query *parsetree, RangeTblEntry *target_rte,
 								Relation target_relation);
 
+extern void fill_extraUpdatedCols(RangeTblEntry *target_rte,
+								  Relation target_relation);
+
 extern Query *get_view_query(Relation view);
 extern const char *view_query_is_auto_updatable(Query *viewquery,
 												bool check_cols);

src/test/regress/expected/updatable_views.out

@@ -1467,6 +1467,41 @@ NOTICE:  drop cascades to 3 other objects
 DETAIL:  drop cascades to view rw_view1
 drop cascades to view rw_view2
 drop cascades to view rw_view3
+-- view on table with GENERATED columns
+CREATE TABLE base_tbl (id int, idplus1 int GENERATED ALWAYS AS (id + 1) STORED);
+CREATE VIEW rw_view1 AS SELECT * FROM base_tbl;
+INSERT INTO base_tbl (id) VALUES (1);
+INSERT INTO rw_view1 (id) VALUES (2);
+INSERT INTO base_tbl (id, idplus1) VALUES (3, DEFAULT);
+INSERT INTO rw_view1 (id, idplus1) VALUES (4, DEFAULT);
+INSERT INTO base_tbl (id, idplus1) VALUES (5, 6);  -- error
+ERROR:  cannot insert into column "idplus1"
+DETAIL:  Column "idplus1" is a generated column.
+INSERT INTO rw_view1 (id, idplus1) VALUES (6, 7);  -- error
+ERROR:  cannot insert into column "idplus1"
+DETAIL:  Column "idplus1" is a generated column.
+SELECT * FROM base_tbl;
+ id | idplus1 
+----+---------
+  1 |       2
+  2 |       3
+  3 |       4
+  4 |       5
+(4 rows)
+
+UPDATE base_tbl SET id = 2000 WHERE id = 2;
+UPDATE rw_view1 SET id = 3000 WHERE id = 3;
+SELECT * FROM base_tbl;
+  id  | idplus1 
+------+---------
+    1 |       2
+    4 |       5
+ 2000 |    2001
+ 3000 |    3001
+(4 rows)
+
+DROP TABLE base_tbl CASCADE;
+NOTICE:  drop cascades to view rw_view1
 -- inheritance tests
 CREATE TABLE base_tbl_parent (a int);
 CREATE TABLE base_tbl_child (CHECK (a > 0)) INHERITS (base_tbl_parent);

src/test/regress/sql/updatable_views.sql

@@ -697,6 +697,27 @@ SELECT events & 4 != 0 AS upd,
 
 DROP TABLE base_tbl CASCADE;
 
+-- view on table with GENERATED columns
+
+CREATE TABLE base_tbl (id int, idplus1 int GENERATED ALWAYS AS (id + 1) STORED);
+CREATE VIEW rw_view1 AS SELECT * FROM base_tbl;
+
+INSERT INTO base_tbl (id) VALUES (1);
+INSERT INTO rw_view1 (id) VALUES (2);
+INSERT INTO base_tbl (id, idplus1) VALUES (3, DEFAULT);
+INSERT INTO rw_view1 (id, idplus1) VALUES (4, DEFAULT);
+INSERT INTO base_tbl (id, idplus1) VALUES (5, 6);  -- error
+INSERT INTO rw_view1 (id, idplus1) VALUES (6, 7);  -- error
+
+SELECT * FROM base_tbl;
+
+UPDATE base_tbl SET id = 2000 WHERE id = 2;
+UPDATE rw_view1 SET id = 3000 WHERE id = 3;
+
+SELECT * FROM base_tbl;
+
+DROP TABLE base_tbl CASCADE;
+
 -- inheritance tests
 
 CREATE TABLE base_tbl_parent (a int);