Fix plpgsql's issues with dropped columns in rowtypes in 8.4 branch.

This is a back-patch of commit dcb2bda9b7042dbf43f876c94ebf35d951de10e9 of
Aug 6 2009, which fixed assorted cases in which plpgsql would fail to cope
with composite types that contain any dropped columns.  Per discussion,
this fix has been out in 9.0 for long enough to make it improbable that it
creates any new bugs, so this is a low-risk fix.  To make it even lower
risk, I did not back-patch the changes in execQual.c, but just accepted
the duplication of code between there and tupconvert.c.  The added files
tupconvert.h and tupconvert.c match their current states in HEAD.

1 files changed, 44 insertions, 0 deletions

diff --git a/src/include/access/tupconvert.h b/src/include/access/tupconvert.h
new file mode 100644
index 00000000000..ab79f09fe81
--- /dev/null
+++ b/src/include/access/tupconvert.h
@@ -0,0 +1,44 @@
+/*-------------------------------------------------------------------------
+ *
+ * tupconvert.h
+ *	  Tuple conversion support.
+ *
+ *
+ * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/access/tupconvert.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TUPCONVERT_H
+#define TUPCONVERT_H
+
+#include "access/htup.h"
+
+
+typedef struct TupleConversionMap
+{
+	TupleDesc	indesc;			/* tupdesc for source rowtype */
+	TupleDesc	outdesc;		/* tupdesc for result rowtype */
+	AttrNumber *attrMap;		/* indexes of input fields, or 0 for null */
+	Datum	   *invalues;		/* workspace for deconstructing source */
+	bool	   *inisnull;
+	Datum	   *outvalues;		/* workspace for constructing result */
+	bool	   *outisnull;
+} TupleConversionMap;
+
+
+extern TupleConversionMap *convert_tuples_by_position(TupleDesc indesc,
+						   TupleDesc outdesc,
+						   const char *msg);
+
+extern TupleConversionMap *convert_tuples_by_name(TupleDesc indesc,
+					   TupleDesc outdesc,
+					   const char *msg);
+
+extern HeapTuple do_convert_tuple(HeapTuple tuple, TupleConversionMap *map);
+
+extern void free_conversion_map(TupleConversionMap *map);
+
+#endif   /* TUPCONVERT_H */