Fix handling of inherited check constraints in ALTER COLUMN TYPE (again).

The previous way of reconstructing check constraints was to do a separate
"ALTER TABLE ONLY tab ADD CONSTRAINT" for each table in an inheritance
hierarchy.  However, that way has no hope of reconstructing the check
constraints' own inheritance properties correctly, as pointed out in
bug #13779 from Jan Dirk Zijlstra.  What we should do instead is to do
a regular "ALTER TABLE", allowing recursion, at the topmost table that
has a particular constraint, and then suppress the work queue entries
for inherited instances of the constraint.

Annoyingly, we'd tried to fix this behavior before, in commit 5ed6546cf,
but we failed to notice that it wasn't reconstructing the pg_constraint
field values correctly.

As long as I'm touching pg_get_constraintdef_worker anyway, tweak it to
always schema-qualify the target table name; this seems like useful backup
to the protections installed by commit 5f173040.

In HEAD/9.5, get rid of get_constraint_relation_oids, which is now unused.
(I could alternatively have modified it to also return conislocal, but that
seemed like a pretty single-purpose API, so let's not pretend it has some
other use.)  It's unused in the back branches as well, but I left it in
place just in case some third-party code has decided to use it.

In HEAD/9.5, also rename pg_get_constraintdef_string to
pg_get_constraintdef_command, as the previous name did nothing to explain
what that entry point did differently from others (and its comment was
equally useless).  Again, that change doesn't seem like material for
back-patching.

I did a bit of re-pgindenting in tablecmds.c in HEAD/9.5, as well.

Otherwise, back-patch to all supported branches.

2 files changed, 1 insertions, 2 deletions

diff --git a/src/include/catalog/pg_constraint.h b/src/include/catalog/pg_constraint.h
index 6f32ac810f..feafc35652 100644
--- a/src/include/catalog/pg_constraint.h
+++ b/src/include/catalog/pg_constraint.h
@@ -247,7 +247,6 @@ extern char *ChooseConstraintName(const char *name1, const char *name2,
 
 extern void AlterConstraintNamespaces(Oid ownerId, Oid oldNspId,
 					  Oid newNspId, bool isType, ObjectAddresses *objsMoved);
-extern void get_constraint_relation_oids(Oid constraint_oid, Oid *conrelid, Oid *confrelid);
 extern Oid	get_relation_constraint_oid(Oid relid, const char *conname, bool missing_ok);
 extern Oid	get_domain_constraint_oid(Oid typid, const char *conname, bool missing_ok);
 
diff --git a/src/include/utils/ruleutils.h b/src/include/utils/ruleutils.h
index 3494b13b0f..fe8bad4914 100644
--- a/src/include/utils/ruleutils.h
+++ b/src/include/utils/ruleutils.h
@@ -21,7 +21,7 @@
 extern char *pg_get_indexdef_string(Oid indexrelid);
 extern char *pg_get_indexdef_columns(Oid indexrelid, bool pretty);
 
-extern char *pg_get_constraintdef_string(Oid constraintId);
+extern char *pg_get_constraintdef_command(Oid constraintId);
 extern char *deparse_expression(Node *expr, List *dpcontext,
 				   bool forceprefix, bool showimplicit);
 extern List *deparse_context_for(const char *aliasname, Oid relid);