Support varlena fields with single-byte headers and unaligned storage.

This commit breaks any code that assumes that the mere act of forming a tuple
(without writing it to disk) does not "toast" any fields.  While all available
regression tests pass, I'm not totally sure that we've fixed every nook and
cranny, especially in contrib.

Greg Stark with some help from Tom Lane

1 files changed, 17 insertions, 1 deletions

diff --git a/src/include/fmgr.h b/src/include/fmgr.h
index f6462d43a89..298cd12c775 100644
--- a/src/include/fmgr.h
+++ b/src/include/fmgr.h
@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/fmgr.h,v 1.49 2007/01/05 22:19:50 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/fmgr.h,v 1.50 2007/04/06 04:21:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -153,6 +153,11 @@ extern void fmgr_info_copy(FmgrInfo *dstinfo, FmgrInfo *srcinfo,
  * if you need a modifiable copy of the input.	Caller is expected to have
  * checked for null inputs first, if necessary.
  *
+ * pg_detoast_datum_packed() will return packed (1-byte header) datums
+ * unmodified.  It will still expand an externally toasted or compressed datum.
+ * The resulting datum can be accessed using VARSIZE_ANY() and VARDATA_ANY()
+ * (beware of multiple evaluations in those macros!)
+ *
  * Note: it'd be nice if these could be macros, but I see no way to do that
  * without evaluating the arguments multiple times, which is NOT acceptable.
  */
@@ -160,6 +165,7 @@ extern struct varlena *pg_detoast_datum(struct varlena * datum);
 extern struct varlena *pg_detoast_datum_copy(struct varlena * datum);
 extern struct varlena *pg_detoast_datum_slice(struct varlena * datum,
 					   int32 first, int32 count);
+extern struct varlena *pg_detoast_datum_packed(struct varlena * datum);
 
 #define PG_DETOAST_DATUM(datum) \
 	pg_detoast_datum((struct varlena *) DatumGetPointer(datum))
@@ -168,6 +174,8 @@ extern struct varlena *pg_detoast_datum_slice(struct varlena * datum,
 #define PG_DETOAST_DATUM_SLICE(datum,f,c) \
 		pg_detoast_datum_slice((struct varlena *) DatumGetPointer(datum), \
 		(int32) f, (int32) c)
+#define PG_DETOAST_DATUM_PACKED(datum) \
+	pg_detoast_datum_packed((struct varlena *) DatumGetPointer(datum))
 
 /*
  * Support for cleaning up detoasted copies of inputs.	This must only
@@ -207,9 +215,13 @@ extern struct varlena *pg_detoast_datum_slice(struct varlena * datum,
 #define PG_GETARG_VARLENA_P(n) PG_DETOAST_DATUM(PG_GETARG_DATUM(n))
 /* DatumGetFoo macros for varlena types will typically look like this: */
 #define DatumGetByteaP(X)			((bytea *) PG_DETOAST_DATUM(X))
+#define DatumGetByteaPP(X)			((bytea *) PG_DETOAST_DATUM_PACKED(X))
 #define DatumGetTextP(X)			((text *) PG_DETOAST_DATUM(X))
+#define DatumGetTextPP(X)			((text *) PG_DETOAST_DATUM_PACKED(X))
 #define DatumGetBpCharP(X)			((BpChar *) PG_DETOAST_DATUM(X))
+#define DatumGetBpCharPP(X)			((BpChar *) PG_DETOAST_DATUM_PACKED(X))
 #define DatumGetVarCharP(X)			((VarChar *) PG_DETOAST_DATUM(X))
+#define DatumGetVarCharPP(X)		((VarChar *) PG_DETOAST_DATUM_PACKED(X))
 #define DatumGetHeapTupleHeader(X)	((HeapTupleHeader) PG_DETOAST_DATUM(X))
 /* And we also offer variants that return an OK-to-write copy */
 #define DatumGetByteaPCopy(X)		((bytea *) PG_DETOAST_DATUM_COPY(X))
@@ -224,9 +236,13 @@ extern struct varlena *pg_detoast_datum_slice(struct varlena * datum,
 #define DatumGetVarCharPSlice(X,m,n) ((VarChar *) PG_DETOAST_DATUM_SLICE(X,m,n))
 /* GETARG macros for varlena types will typically look like this: */
 #define PG_GETARG_BYTEA_P(n)		DatumGetByteaP(PG_GETARG_DATUM(n))
+#define PG_GETARG_BYTEA_PP(n)		DatumGetByteaPP(PG_GETARG_DATUM(n))
 #define PG_GETARG_TEXT_P(n)			DatumGetTextP(PG_GETARG_DATUM(n))
+#define PG_GETARG_TEXT_PP(n)		DatumGetTextPP(PG_GETARG_DATUM(n))
 #define PG_GETARG_BPCHAR_P(n)		DatumGetBpCharP(PG_GETARG_DATUM(n))
+#define PG_GETARG_BPCHAR_PP(n)		DatumGetBpCharPP(PG_GETARG_DATUM(n))
 #define PG_GETARG_VARCHAR_P(n)		DatumGetVarCharP(PG_GETARG_DATUM(n))
+#define PG_GETARG_VARCHAR_PP(n)		DatumGetVarCharPP(PG_GETARG_DATUM(n))
 #define PG_GETARG_HEAPTUPLEHEADER(n)	DatumGetHeapTupleHeader(PG_GETARG_DATUM(n))
 /* And we also offer variants that return an OK-to-write copy */
 #define PG_GETARG_BYTEA_P_COPY(n)	DatumGetByteaPCopy(PG_GETARG_DATUM(n))