Make the world very nearly safe for composite-type columns in tables.

1. Solve the problem of not having TOAST references hiding inside composite
values by establishing the rule that toasting only goes one level deep:
a tuple can contain toasted fields, but a composite-type datum that is
to be inserted into a tuple cannot.  Enforcing this in heap_formtuple
is relatively cheap and it avoids a large increase in the cost of running
the tuptoaster during final storage of a row.
2. Fix some interesting problems in expansion of inherited queries that
reference whole-row variables.  We never really did this correctly before,
but it's now relatively painless to solve by expanding the parent's
whole-row Var into a RowExpr() selecting the proper columns from the
child.
If you dike out the preventive check in CheckAttributeType(),
composite-type columns now seem to actually work.  However, we surely
cannot ship them like this --- without I/O for composite types, you
can't get pg_dump to dump tables containing them.  So a little more
work still to do.

3 files changed, 19 insertions, 3 deletions

diff --git a/src/include/access/tuptoaster.h b/src/include/access/tuptoaster.h
index 2e2fcc91543..3332e9ab62b 100644
--- a/src/include/access/tuptoaster.h
+++ b/src/include/access/tuptoaster.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 2000-2003, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/include/access/tuptoaster.h,v 1.17 2003/11/29 22:40:55 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/access/tuptoaster.h,v 1.18 2004/06/05 01:55:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -111,6 +111,18 @@ extern varattrib *heap_tuple_untoast_attr_slice(varattrib *attr,
 							  int32 slicelength);
 
 /* ----------
+ * toast_flatten_tuple_attribute -
+ *
+ *	If a Datum is of composite type, "flatten" it to contain no toasted fields.
+ *	This must be invoked on any potentially-composite field that is to be
+ *	inserted into a tuple.  Doing this preserves the invariant that toasting
+ *	goes only one level deep in a tuple.
+ * ----------
+ */
+extern Datum toast_flatten_tuple_attribute(Datum value,
+										   Oid typeId, int32 typeMod);
+
+/* ----------
  * toast_compress_datum -
  *
  *	Create a compressed version of a varlena datum, if possible
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 91114fb03b7..a75ddb8262d 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.95 2004/06/01 03:03:05 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.96 2004/06/05 01:55:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -91,6 +91,7 @@ typedef struct QualCost
  *				appropriate projections have been done (ie, output width)
  *		reltargetlist - List of Var nodes for the attributes we need to
  *						output from this relation (in no particular order)
+ *						NOTE: in a child relation, may contain RowExprs
  *		pathlist - List of Path nodes, one for each potentially useful
  *				   method of generating the relation
  *		cheapest_startup_path - the pathlist member with lowest startup cost
diff --git a/src/include/utils/typcache.h b/src/include/utils/typcache.h
index 8b85f517000..0856fddea14 100644
--- a/src/include/utils/typcache.h
+++ b/src/include/utils/typcache.h
@@ -9,7 +9,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/typcache.h,v 1.3 2004/04/01 21:28:46 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/utils/typcache.h,v 1.4 2004/06/05 01:55:05 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -76,6 +76,9 @@ extern TypeCacheEntry *lookup_type_cache(Oid type_id, int flags);
 
 extern TupleDesc lookup_rowtype_tupdesc(Oid type_id, int32 typmod);
 
+extern TupleDesc lookup_rowtype_tupdesc_noerror(Oid type_id, int32 typmod,
+												bool noError);
+
 extern void assign_record_type_typmod(TupleDesc tupDesc);
 
 extern void flush_rowtype_cache(Oid type_id);