Correctly check updatability of columns targeted by INSERT...DEFAULT.

If a view has some updatable and some non-updatable columns, we failed
to verify updatability of any columns for which an INSERT or UPDATE
on the view explicitly specifies a DEFAULT item (unless the view has
a declared default for that column, which is rare anyway, and one
would almost certainly not write one for a non-updatable column).
This would lead to an unexpected "attribute number N not found in
view targetlist" error rather than the intended error.

Per bug #18546 from Alexander Lakhin.  This bug is old, so back-patch
to all supported branches.

Discussion: https://postgr.es/m/18546-84a292e759a9361d@postgresql.org

diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index c4dd848b885f1c1ed780c4ea5aa1f3f5d226f179..0438f26620e5bbae86ca98362ae78347279dd9cd 100644 (file)
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -2983,7 +2983,7 @@ relation_is_updatable(Oid reloid,
  *
  * This is used with simply-updatable views to map column-permissions sets for
  * the view columns onto the matching columns in the underlying base relation.
- * The targetlist is expected to be a list of plain Vars of the underlying
+ * Relevant entries in the targetlist must be plain Vars of the underlying
  * relation (as per the checks above in view_query_is_auto_updatable).
  */
 static Bitmapset *
@@ -3080,6 +3080,9 @@ rewriteTargetView(Query *parsetree, Relation view)
         */
        viewquery = copyObject(get_view_query(view));
 
+       /* Locate RTE describing the view in the outer query */
+       view_rte = rt_fetch(parsetree->resultRelation, parsetree->rtable);
+
        /* The view must be updatable, else fail */
        auto_update_detail =
                view_query_is_auto_updatable(viewquery,
@@ -3122,17 +3125,26 @@ rewriteTargetView(Query *parsetree, Relation view)
        }
 
        /*
-        * For INSERT/UPDATE the modified columns must all be updatable. Note that
-        * we get the modified columns from the query's targetlist, not from the
-        * result RTE's insertedCols and/or updatedCols set, since
-        * rewriteTargetListIU may have added additional targetlist entries for
-        * view defaults, and these must also be updatable.
+        * For INSERT/UPDATE the modified columns must all be updatable.
         */
        if (parsetree->commandType != CMD_DELETE)
        {
-               Bitmapset  *modified_cols = NULL;
+               Bitmapset  *modified_cols;
                char       *non_updatable_col;
 
+               /*
+                * Compute the set of modified columns as those listed in the result
+                * RTE's insertedCols and/or updatedCols sets plus those that are
+                * targets of the query's targetlist(s).  We must consider the query's
+                * targetlist because rewriteTargetListIU may have added additional
+                * targetlist entries for view defaults, and these must also be
+                * updatable.  But rewriteTargetListIU can also remove entries if they
+                * are DEFAULT markers and the column's default is NULL, so
+                * considering only the targetlist would also be wrong.
+                */
+               modified_cols = bms_union(view_rte->insertedCols,
+                                                                 view_rte->updatedCols);
+
                foreach(lc, parsetree->targetList)
                {
                        TargetEntry *tle = (TargetEntry *) lfirst(lc);
@@ -3190,9 +3202,6 @@ rewriteTargetView(Query *parsetree, Relation view)
                }
        }
 
-       /* Locate RTE describing the view in the outer query */
-       view_rte = rt_fetch(parsetree->resultRelation, parsetree->rtable);
-
        /*
         * If we get here, view_query_is_auto_updatable() has verified that the
         * view contains a single base relation.

diff --git a/src/test/regress/expected/updatable_views.out b/src/test/regress/expected/updatable_views.out
index 77082087b739be5f7245e67118743000c71124ba..9e0fd6bba7365bf705a758dfa5bc54322d8df424 100644 (file)
--- a/src/test/regress/expected/updatable_views.out
+++ b/src/test/regress/expected/updatable_views.out
@@ -1361,6 +1361,9 @@ DETAIL:  View columns that refer to system columns are not updatable.
 INSERT INTO rw_view1 (s, c, a) VALUES (null, null, 1.1); -- should fail
 ERROR:  cannot insert into column "s" of view "rw_view1"
 DETAIL:  View columns that are not columns of their base relation are not updatable.
+INSERT INTO rw_view1 (s, c, a) VALUES (default, default, 1.1); -- should fail
+ERROR:  cannot insert into column "s" of view "rw_view1"
+DETAIL:  View columns that are not columns of their base relation are not updatable.
 INSERT INTO rw_view1 (a) VALUES (1.1) RETURNING a, s, c; -- OK
   a  |         s         |         c         
 -----+-------------------+-------------------

diff --git a/src/test/regress/sql/updatable_views.sql b/src/test/regress/sql/updatable_views.sql
index 08983f1713654ed7ca233f6e0711eea9b3e1a67d..3fe8685854925e6995f992c4d1724a7ca527f334 100644 (file)
--- a/src/test/regress/sql/updatable_views.sql
+++ b/src/test/regress/sql/updatable_views.sql
@@ -665,6 +665,7 @@ CREATE VIEW rw_view1 AS
 
 INSERT INTO rw_view1 VALUES (null, null, 1.1, null); -- should fail
 INSERT INTO rw_view1 (s, c, a) VALUES (null, null, 1.1); -- should fail
+INSERT INTO rw_view1 (s, c, a) VALUES (default, default, 1.1); -- should fail
 INSERT INTO rw_view1 (a) VALUES (1.1) RETURNING a, s, c; -- OK
 UPDATE rw_view1 SET s = s WHERE a = 1.1; -- should fail
 UPDATE rw_view1 SET a = 1.05 WHERE a = 1.1 RETURNING s; -- OK