Further fixing for multi-row VALUES lists for updatable views.

Previously, rewriteTargetListIU() generated a list of attribute
numbers from the targetlist, which were passed to rewriteValuesRTE(),
which expected them to contain the same number of entries as there are
columns in the VALUES RTE, and to be in the same order. That was fine
when the target relation was a table, but for an updatable view it
could be broken in at least three different ways ---
rewriteTargetListIU() could insert additional targetlist entries for
view columns with defaults, the view columns could be in a different
order from the columns of the underlying base relation, and targetlist
entries could be merged together when assigning to elements of an
array or composite type. As a result, when recursing to the base
relation, the list of attribute numbers generated from the rewritten
targetlist could no longer be relied upon to match the columns of the
VALUES RTE. We got away with that prior to 41531e42d3 because it used
to always be the case that rewriteValuesRTE() did nothing for the
underlying base relation, since all DEFAULTS had already been replaced
when it was initially invoked for the view, but that was incorrect
because it failed to apply defaults from the base relation.

Fix this by examining the targetlist entries more carefully and
picking out just those that are simple Vars referencing the VALUES
RTE. That's sufficient for the purposes of rewriteValuesRTE(), which
is only responsible for dealing with DEFAULT items in the VALUES
RTE. Any DEFAULT item in the VALUES RTE that doesn't have a matching
simple-Var-assignment in the targetlist is an error which we complain
about, but in theory that ought to be impossible.

Additionally, move this code into rewriteValuesRTE() to give a clearer
separation of concerns between the 2 functions. There is no need for
rewriteTargetListIU() to know about the details of the VALUES RTE.

While at it, fix the comment for rewriteValuesRTE() which claimed that
it doesn't support array element and field assignments --- that hasn't
been true since a3c7a993d5 (9.6 and later).

Back-patch to all supported versions, with minor differences for the
pre-9.6 branches, which don't support array element and field
assignments to the same column in multi-row VALUES lists.

Reviewed by Amit Langote.

Discussion: https://postgr.es/m/15623-5d67a46788ec8b7f@postgresql.org

2 files changed, 47 insertions, 4 deletions

diff --git a/src/test/regress/expected/updatable_views.out b/src/test/regress/expected/updatable_views.out
index 58be360f9bd..338f8d7fb2d 100644
--- a/src/test/regress/expected/updatable_views.out
+++ b/src/test/regress/expected/updatable_views.out
@@ -2665,6 +2665,7 @@ insert into base_tab_def_view values (12), (13);
 insert into base_tab_def_view values (14, default, default, default, default);
 insert into base_tab_def_view values (15, default, default, default, default),
                                      (16, default, default, default, default);
+insert into base_tab_def_view values (17), (default);
 select * from base_tab_def order by a;
  a  |       b       |       c       |      d       | e 
 ----+---------------+---------------+--------------+---
@@ -2680,7 +2681,9 @@ select * from base_tab_def order by a;
  14 | View default  | Table default | View default | 
  15 | View default  | Table default | View default | 
  16 | View default  | Table default | View default | 
-(12 rows)
+ 17 | View default  | Table default | View default | 
+    | View default  | Table default | View default | 
+(14 rows)
 
 -- Adding an INSTEAD OF trigger should cause NULLs to be inserted instead of
 -- table defaults, where there are no view defaults.
@@ -2706,6 +2709,7 @@ insert into base_tab_def_view values (12), (13);
 insert into base_tab_def_view values (14, default, default, default, default);
 insert into base_tab_def_view values (15, default, default, default, default),
                                      (16, default, default, default, default);
+insert into base_tab_def_view values (17), (default);
 select * from base_tab_def order by a;
  a  |       b       |       c       |      d       | e 
 ----+---------------+---------------+--------------+---
@@ -2721,7 +2725,9 @@ select * from base_tab_def order by a;
  14 | View default  |               | View default | 
  15 | View default  |               | View default | 
  16 | View default  |               | View default | 
-(12 rows)
+ 17 | View default  |               | View default | 
+    | View default  |               | View default | 
+(14 rows)
 
 -- Using an unconditional DO INSTEAD rule should also cause NULLs to be
 -- inserted where there are no view defaults.
@@ -2740,6 +2746,7 @@ insert into base_tab_def_view values (12), (13);
 insert into base_tab_def_view values (14, default, default, default, default);
 insert into base_tab_def_view values (15, default, default, default, default),
                                      (16, default, default, default, default);
+insert into base_tab_def_view values (17), (default);
 select * from base_tab_def order by a;
  a  |       b       |       c       |      d       | e 
 ----+---------------+---------------+--------------+---
@@ -2755,7 +2762,9 @@ select * from base_tab_def order by a;
  14 | View default  |               | View default | 
  15 | View default  |               | View default | 
  16 | View default  |               | View default | 
-(12 rows)
+ 17 | View default  |               | View default | 
+    | View default  |               | View default | 
+(14 rows)
 
 -- A DO ALSO rule should cause each row to be inserted twice. The first
 -- insert should behave the same as an auto-updatable view (using table
@@ -2776,6 +2785,7 @@ insert into base_tab_def_view values (12), (13);
 insert into base_tab_def_view values (14, default, default, default, default);
 insert into base_tab_def_view values (15, default, default, default, default),
                                      (16, default, default, default, default);
+insert into base_tab_def_view values (17), (default);
 select * from base_tab_def order by a, c NULLS LAST;
  a  |       b       |       c       |      d       | e 
 ----+---------------+---------------+--------------+---
@@ -2797,7 +2807,26 @@ select * from base_tab_def order by a, c NULLS LAST;
  15 | View default  |               | View default | 
  16 | View default  | Table default | View default | 
  16 | View default  |               | View default | 
-(18 rows)
+ 17 | View default  | Table default | View default | 
+ 17 | View default  |               | View default | 
+    | View default  | Table default | View default | 
+    | View default  |               | View default | 
+(22 rows)
 
 drop view base_tab_def_view;
 drop table base_tab_def;
+-- Test defaults with array assignments
+create table base_tab (a serial, b int[], c text, d text default 'Table default');
+create view base_tab_view as select c, a, b from base_tab;
+alter view base_tab_view alter column c set default 'View default';
+insert into base_tab_view (b[1], b[2], c, b[5], b[4], a, b[3])
+values (1, 2, default, 5, 4, default, 3), (10, 11, 'C value', 14, 13, 100, 12);
+select * from base_tab order by a;
+  a  |        b         |      c       |       d       
+-----+------------------+--------------+---------------
+   1 | {1,2,3,4,5}      | View default | Table default
+ 100 | {10,11,12,13,14} | C value      | Table default
+(2 rows)
+
+drop view base_tab_view;
+drop table base_tab;
diff --git a/src/test/regress/sql/updatable_views.sql b/src/test/regress/sql/updatable_views.sql
index 1bbce119e43..e9ef7b1498f 100644
--- a/src/test/regress/sql/updatable_views.sql
+++ b/src/test/regress/sql/updatable_views.sql
@@ -1321,6 +1321,7 @@ insert into base_tab_def_view values (12), (13);
 insert into base_tab_def_view values (14, default, default, default, default);
 insert into base_tab_def_view values (15, default, default, default, default),
                                      (16, default, default, default, default);
+insert into base_tab_def_view values (17), (default);
 select * from base_tab_def order by a;
 
 -- Adding an INSTEAD OF trigger should cause NULLs to be inserted instead of
@@ -1347,6 +1348,7 @@ insert into base_tab_def_view values (12), (13);
 insert into base_tab_def_view values (14, default, default, default, default);
 insert into base_tab_def_view values (15, default, default, default, default),
                                      (16, default, default, default, default);
+insert into base_tab_def_view values (17), (default);
 select * from base_tab_def order by a;
 
 -- Using an unconditional DO INSTEAD rule should also cause NULLs to be
@@ -1366,6 +1368,7 @@ insert into base_tab_def_view values (12), (13);
 insert into base_tab_def_view values (14, default, default, default, default);
 insert into base_tab_def_view values (15, default, default, default, default),
                                      (16, default, default, default, default);
+insert into base_tab_def_view values (17), (default);
 select * from base_tab_def order by a;
 
 -- A DO ALSO rule should cause each row to be inserted twice. The first
@@ -1387,7 +1390,18 @@ insert into base_tab_def_view values (12), (13);
 insert into base_tab_def_view values (14, default, default, default, default);
 insert into base_tab_def_view values (15, default, default, default, default),
                                      (16, default, default, default, default);
+insert into base_tab_def_view values (17), (default);
 select * from base_tab_def order by a, c NULLS LAST;
 
 drop view base_tab_def_view;
 drop table base_tab_def;
+
+-- Test defaults with array assignments
+create table base_tab (a serial, b int[], c text, d text default 'Table default');
+create view base_tab_view as select c, a, b from base_tab;
+alter view base_tab_view alter column c set default 'View default';
+insert into base_tab_view (b[1], b[2], c, b[5], b[4], a, b[3])
+values (1, 2, default, 5, 4, default, 3), (10, 11, 'C value', 14, 13, 100, 12);
+select * from base_tab order by a;
+drop view base_tab_view;
+drop table base_tab;