When WCOs are present, disable direct foreign table modification.

If the user modifies a view that has CHECK OPTIONs and this gets
translated into a modification to an underlying relation which happens
to be a foreign table, the check options should be enforced.  In the
normal code path, that was happening properly, but it was not working
properly for "direct" modification because the whole operation gets
pushed to the remote side in that case and we never have an option to
enforce the constraint against individual tuples.  Fix by disabling
direct modification when there is a need to enforce CHECK OPTIONs.

Etsuro Fujita, reviewed by Kyotaro Horiguchi and by me.

Discussion: http://postgr.es/m/f8a48f54-6f02-9c8a-5250-9791603171ee@lab.ntt.co.jp

diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out
index 5bb3d97401e978911a66f32341bdce458615c773..c19b3318c7259ca742c740d92414da897bf88efc 100644 (file)
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -5894,6 +5894,66 @@ INSERT INTO ft1(c1, c2) VALUES(1111, 2);
 UPDATE ft1 SET c2 = c2 + 1 WHERE c1 = 1;
 ALTER FOREIGN TABLE ft1 DROP CONSTRAINT ft1_c2negative;
 -- ===================================================================
+-- test WITH CHECK OPTION constraints
+-- ===================================================================
+CREATE TABLE base_tbl (a int, b int);
+CREATE FOREIGN TABLE foreign_tbl (a int, b int)
+  SERVER loopback OPTIONS(table_name 'base_tbl');
+CREATE VIEW rw_view AS SELECT * FROM foreign_tbl
+  WHERE a < b WITH CHECK OPTION;
+\d+ rw_view
+                           View "public.rw_view"
+ Column |  Type   | Collation | Nullable | Default | Storage | Description 
+--------+---------+-----------+----------+---------+---------+-------------
+ a      | integer |           |          |         | plain   | 
+ b      | integer |           |          |         | plain   | 
+View definition:
+ SELECT foreign_tbl.a,
+    foreign_tbl.b
+   FROM foreign_tbl
+  WHERE foreign_tbl.a < foreign_tbl.b;
+Options: check_option=cascaded
+
+INSERT INTO rw_view VALUES (0, 10); -- ok
+INSERT INTO rw_view VALUES (10, 0); -- should fail
+ERROR:  new row violates check option for view "rw_view"
+DETAIL:  Failing row contains (10, 0).
+EXPLAIN (VERBOSE, COSTS OFF)
+UPDATE rw_view SET b = 20 WHERE a = 0; -- not pushed down
+                                            QUERY PLAN                                            
+--------------------------------------------------------------------------------------------------
+ Update on public.foreign_tbl
+   Remote SQL: UPDATE public.base_tbl SET b = $2 WHERE ctid = $1
+   ->  Foreign Scan on public.foreign_tbl
+         Output: foreign_tbl.a, 20, foreign_tbl.ctid
+         Remote SQL: SELECT a, ctid FROM public.base_tbl WHERE ((a < b)) AND ((a = 0)) FOR UPDATE
+(5 rows)
+
+UPDATE rw_view SET b = 20 WHERE a = 0; -- ok
+EXPLAIN (VERBOSE, COSTS OFF)
+UPDATE rw_view SET b = -20 WHERE a = 0; -- not pushed down
+                                            QUERY PLAN                                            
+--------------------------------------------------------------------------------------------------
+ Update on public.foreign_tbl
+   Remote SQL: UPDATE public.base_tbl SET b = $2 WHERE ctid = $1
+   ->  Foreign Scan on public.foreign_tbl
+         Output: foreign_tbl.a, '-20'::integer, foreign_tbl.ctid
+         Remote SQL: SELECT a, ctid FROM public.base_tbl WHERE ((a < b)) AND ((a = 0)) FOR UPDATE
+(5 rows)
+
+UPDATE rw_view SET b = -20 WHERE a = 0; -- should fail
+ERROR:  new row violates check option for view "rw_view"
+DETAIL:  Failing row contains (0, -20).
+SELECT * FROM foreign_tbl;
+ a | b  
+---+----
+ 0 | 20
+(1 row)
+
+DROP FOREIGN TABLE foreign_tbl CASCADE;
+NOTICE:  drop cascades to view rw_view
+DROP TABLE base_tbl;
+-- ===================================================================
 -- test serial columns (ie, sequence-based defaults)
 -- ===================================================================
 create table loc1 (f1 serial, f2 text);

diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql
index bb92189b0e68065b496a35a87efba7f6a0d69ac8..5f65d9d966ce55e3e472e632c981b6ae902dffca 100644 (file)
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -1180,6 +1180,30 @@ INSERT INTO ft1(c1, c2) VALUES(1111, 2);
 UPDATE ft1 SET c2 = c2 + 1 WHERE c1 = 1;
 ALTER FOREIGN TABLE ft1 DROP CONSTRAINT ft1_c2negative;
 
+-- ===================================================================
+-- test WITH CHECK OPTION constraints
+-- ===================================================================
+
+CREATE TABLE base_tbl (a int, b int);
+CREATE FOREIGN TABLE foreign_tbl (a int, b int)
+  SERVER loopback OPTIONS(table_name 'base_tbl');
+CREATE VIEW rw_view AS SELECT * FROM foreign_tbl
+  WHERE a < b WITH CHECK OPTION;
+\d+ rw_view
+
+INSERT INTO rw_view VALUES (0, 10); -- ok
+INSERT INTO rw_view VALUES (10, 0); -- should fail
+EXPLAIN (VERBOSE, COSTS OFF)
+UPDATE rw_view SET b = 20 WHERE a = 0; -- not pushed down
+UPDATE rw_view SET b = 20 WHERE a = 0; -- ok
+EXPLAIN (VERBOSE, COSTS OFF)
+UPDATE rw_view SET b = -20 WHERE a = 0; -- not pushed down
+UPDATE rw_view SET b = -20 WHERE a = 0; -- should fail
+SELECT * FROM foreign_tbl;
+
+DROP FOREIGN TABLE foreign_tbl CASCADE;
+DROP TABLE base_tbl;
+
 -- ===================================================================
 -- test serial columns (ie, sequence-based defaults)
 -- ===================================================================

diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index 23558e7ec08e60d25301f3178bce8991f3793806..d83fc9e52b1b800507aca7e45cc469fbc833a2e2 100644 (file)
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -498,8 +498,10 @@
    postgres_fdw attempts to optimize the query execution by
    sending the whole query to the remote server if there are no query
    WHERE clauses that cannot be sent to the remote server,
-   no local joins for the query, and no row-level local BEFORE or
-   AFTER triggers on the target table.  In UPDATE,
+   no local joins for the query, no row-level local BEFORE or
+   AFTER triggers on the target table, and no
+   CHECK OPTION constraints from parent views.
+   In UPDATE,
    expressions to assign to target columns must use only built-in data types,
    IMMUTABLE operators, or IMMUTABLE functions,
    to reduce the risk of misexecution of the query.

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 9d838e4f39a2b1a219f5d5cd7c6bc3ead90eb44d..5c934f223da0fd138294ab958ae658818c8f83b3 100644 (file)
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -6500,8 +6500,10 @@ make_modifytable(PlannerInfo *root,
        }
 
        /*
-        * If the target foreign table has any row-level triggers, we can't
-        * modify the foreign table directly.
+        * Try to modify the foreign table directly if (1) the FDW provides
+        * callback functions needed for that, (2) there are no row-level
+        * triggers on the foreign table, and (3) there are no WITH CHECK
+        * OPTIONs from parent views.
         */
        direct_modify = false;
        if (fdwroutine != NULL &&
@@ -6509,6 +6511,7 @@ make_modifytable(PlannerInfo *root,
            fdwroutine->BeginDirectModify != NULL &&
            fdwroutine->IterateDirectModify != NULL &&
            fdwroutine->EndDirectModify != NULL &&
+           withCheckOptionLists == NIL &&
            !has_row_triggers(root, rti, operation))
            direct_modify = fdwroutine->PlanDirectModify(root, node, rti, i);
        if (direct_modify)