Fix another bug in merging of inherited CHECK constraints.

It's not good for an inherited child constraint to be marked connoinherit;
that would result in the constraint not propagating to grandchild tables,
if any are created later.  The code mostly prevented this from happening
but there was one case that was missed.

This is somewhat related to commit e55a946a8, which also tightened checks
on constraint merging.  Hence, back-patch to 9.2 like that one.  This isn't
so much because there's a concrete feature-related reason to stop there,
as to avoid having more distinct behaviors than we have to in this area.

Amit Langote

Discussion: <b28ee774-7009-313d-dd55-5bdd81242c41@lab.ntt.co.jp>

diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 3ba43a3edaf8bdc820a162e14d4c9fdcf400b06e..3097ec53c104089866a8173548bf3e9b7bb380f0 100644 (file)
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -2344,6 +2344,17 @@ MergeWithExistingConstraint(Relation rel, char *ccname, Node *expr,
                         errmsg("constraint \"%s\" conflicts with non-inherited constraint on relation \"%s\"",
                                ccname, RelationGetRelationName(rel))));
 
+           /*
+            * Must not change an existing inherited constraint to "no
+            * inherit" status.  That's because inherited constraints should
+            * be able to propagate to lower-level children.
+            */
+           if (con->coninhcount > 0 && is_no_inherit)
+               ereport(ERROR,
+                       (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+                        errmsg("constraint \"%s\" conflicts with inherited constraint on relation \"%s\"",
+                               ccname, RelationGetRelationName(rel))));
+
            /*
             * If the child constraint is "not valid" then cannot merge with a
             * valid parent constraint

diff --git a/src/test/regress/expected/inherit.out b/src/test/regress/expected/inherit.out
index fa3d9029417493ac4741e95ef59371986ef2a6d2..978d3a1a3390decaeec1da48fb5eba92b30ea9c4 100644 (file)
--- a/src/test/regress/expected/inherit.out
+++ b/src/test/regress/expected/inherit.out
@@ -646,6 +646,9 @@ Check constraints:
     "p2chk" CHECK (ff1 > 10)
 Inherits: p1
 
+-- Test that child does not override inheritable constraints of the parent
+create table c2 (constraint p2chk check (ff1 > 10) no inherit) inherits (p1);  --fails
+ERROR:  constraint "p2chk" conflicts with inherited constraint on relation "c2"
 drop table p1 cascade;
 NOTICE:  drop cascades to table c1
 -- Tests for casting between the rowtypes of parent and child

diff --git a/src/test/regress/sql/inherit.sql b/src/test/regress/sql/inherit.sql
index b64221f7eeabd7b114fbdcc404fbf3d3d4833026..8bc5ef4813d7966d716a8f60578e4ab6462ad992 100644 (file)
--- a/src/test/regress/sql/inherit.sql
+++ b/src/test/regress/sql/inherit.sql
@@ -157,6 +157,9 @@ create table c1 () inherits (p1);
 \d p1
 \d c1
 
+-- Test that child does not override inheritable constraints of the parent
+create table c2 (constraint p2chk check (ff1 > 10) no inherit) inherits (p1);  --fails
+
 drop table p1 cascade;
 
 -- Tests for casting between the rowtypes of parent and child