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 c6679e4fc) 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

2 files changed, 56 insertions, 0 deletions

diff --git a/src/test/regress/expected/updatable_views.out b/src/test/regress/expected/updatable_views.out
index caed1c19ec7..6a977006efc 100644
--- a/src/test/regress/expected/updatable_views.out
+++ b/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);
diff --git a/src/test/regress/sql/updatable_views.sql b/src/test/regress/sql/updatable_views.sql
index 64f23d0902e..09328e582b2 100644
--- a/src/test/regress/sql/updatable_views.sql
+++ b/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);