diff -Nacr ./doc/src/sgml/func.sgml.orig ./doc/src/sgml/func.sgml
*** ./doc/src/sgml/func.sgml.orig	Mon Jun 20 15:38:23 2005
--- ./doc/src/sgml/func.sgml	Mon Jun 20 15:45:51 2005
***************
*** 2187,2192 ****
--- 2187,2200 ----
        </row>
  
        <row>
+        <entry><literal><function>pg_datum_length</function>(<parameter>string</parameter>)</literal></entry>
+        <entry><type>integer</type></entry>
+        <entry>Number of bytes (before toast decompression) in string</entry>
+        <entry><literal>pg_datum_length( 'jo\\000se'::bytea)</literal></entry>
+        <entry><literal>5</literal></entry>
+       </row>
+ 
+       <row>
         <entry><literal><function>position</function>(<parameter>substring</parameter> in <parameter>string</parameter>)</literal></entry>
         <entry><type>integer</type></entry>
         <entry>Location of specified substring</entry>
diff -Nacr ./src/backend/access/heap/tuptoaster.c.orig ./src/backend/access/heap/tuptoaster.c
*** ./src/backend/access/heap/tuptoaster.c.orig	Mon Jun 20 17:11:37 2005
--- ./src/backend/access/heap/tuptoaster.c	Mon Jun 20 17:11:44 2005
***************
*** 1436,1438 ****
--- 1436,1482 ----
  
  	return result;
  }
+ 
+ /* ----------
+  * toast_datum_size
+  *
+  *	Show the (possibly compressed) size of a datum
+  * ----------
+  */
+ Size 
+ toast_datum_size(Datum value)
+ {
+ 
+ 	varattrib	*attr = (varattrib *) DatumGetPointer(value);
+ 	Size		result;
+ 
+ 	if (VARATT_IS_EXTERNAL(attr))
+ 	{
+ 		/*
+ 		 * Attribute is stored externally - If it is compressed too, 
+ 		 * then we need to get the external datum and calculate its size,
+ 		 * otherwise we just use the external rawsize.
+ 		 */
+ 		if (VARATT_IS_COMPRESSED(attr))
+ 		{
+ 			varattrib		*attrext = toast_fetch_datum(attr);
+ 			result = VARSIZE(attrext);
+ 			pfree(attrext);
+ 		}
+ 		else
+ 		{
+ 			result = attr->va_content.va_external.va_rawsize;
+ 		}
+ 	}
+ 	else
+ 	{
+ 		/*
+ 		 * Attribute is stored inline either compressed or not, just
+ 		 * calculate the size of the datum in either case.
+ 		 */
+ 		result = VARSIZE(attr);
+ 	}
+ 
+ 	return result;
+ 	
+ }
diff -Nacr ./src/backend/utils/adt/varlena.c.orig ./src/backend/utils/adt/varlena.c
*** ./src/backend/utils/adt/varlena.c.orig	Mon Jun 20 14:28:03 2005
--- ./src/backend/utils/adt/varlena.c	Mon Jun 20 17:17:58 2005
***************
*** 28,33 ****
--- 28,34 ----
  #include "utils/builtins.h"
  #include "utils/lsyscache.h"
  #include "utils/pg_locale.h"
+ #include "utils/syscache.h"
  
  
  typedef struct varlena unknown;
***************
*** 2330,2333 ****
--- 2331,2396 ----
  
  	result_text = PG_STR_GET_TEXT(hexsum);
  	PG_RETURN_TEXT_P(result_text);
+ }
+ 
+ /* 
+  * Show the (possibly compressed) length of a datum.
+  */
+ Datum
+ pg_datum_length(PG_FUNCTION_ARGS)
+ {
+ 
+ 	Datum			value = PG_GETARG_DATUM(0);
+ 	int				result;
+ 
+ 
+ 	if (fcinfo->flinfo->fn_extra == NULL)
+ 	{
+ 		/*
+ 		 * On the first call lookup the datatype of the supplied argument
+ 		 * and check if is a varlena.
+ 		 */
+ 		Oid				argtypeid = get_fn_expr_argtype(fcinfo->flinfo, 0);
+ 		HeapTuple		tp;
+ 		int				typlen = 0;
+ 		
+ 
+ 		tp = SearchSysCache(TYPEOID,
+ 							ObjectIdGetDatum(argtypeid),
+ 							0, 0, 0);
+ 		if (HeapTupleIsValid(tp)) 
+ 		{
+ 			Form_pg_type typtup = (Form_pg_type) GETSTRUCT(tp);
+ 			typlen = typtup->typlen;
+ 			ReleaseSysCache(tp);
+ 		}
+ 		else
+ 		{
+ 			/* Oid not in pg_type, should never happen. */
+ 			ereport(ERROR,
+ 					(errcode(ERRCODE_INTERNAL_ERROR),
+ 					 errmsg("invalid typid: %u", argtypeid)));
+ 		}
+ 
+ 
+ 		if ( typlen != -1 )
+ 		{
+ 			/* Not a varlena. */
+ 			ereport(ERROR,
+ 					(errcode(ERRCODE_DATATYPE_MISMATCH),
+ 					 errmsg("function is only applicable to varlena types")));
+ 		}
+ 
+ 
+ 		/* 
+ 		 * Allocate fn_extra so we don't go here again! 
+ 		 */
+ 		fcinfo->flinfo->fn_extra = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
+ 													 sizeof(int));
+ 	}
+ 	
+ 
+ 	result = toast_datum_size(value) - VARHDRSZ;
+ 
+ 	PG_RETURN_INT32(result);
  }
diff -Nacr ./src/include/access/tuptoaster.h.orig ./src/include/access/tuptoaster.h
*** ./src/include/access/tuptoaster.h.orig	Mon Mar 21 13:24:04 2005
--- ./src/include/access/tuptoaster.h	Sun Jun 19 14:45:18 2005
***************
*** 138,141 ****
--- 138,149 ----
   */
  extern Size toast_raw_datum_size(Datum value);
  
+ /* ----------
+  * toast_datum_size -
+  *
+  *	Return the (possibly compressed) size of a varlena datum
+  * ----------
+  */
+ extern Size toast_datum_size(Datum value);
+ 
  #endif   /* TUPTOASTER_H */
diff -Nacr ./src/include/catalog/pg_proc.h.orig ./src/include/catalog/pg_proc.h
*** ./src/include/catalog/pg_proc.h.orig	Wed Jun 15 09:04:41 2005
--- ./src/include/catalog/pg_proc.h	Sun Jun 19 17:08:35 2005
***************
*** 3655,3660 ****
--- 3655,3664 ----
  DATA(insert OID = 2560 (  pg_postmaster_start_time PGNSP PGUID 12 f f t f s 0 1184 "" _null_ _null_ _null_ pgsql_postmaster_start_time - _null_ ));
  DESCR("postmaster start time");
  
+ /* Toast compressed length */
+ DATA(insert OID = 2561 (  pg_datum_length	   PGNSP PGUID 12 f f t f i 1 23 "2276" _null_ _null_ _null_  pg_datum_length - _null_ ));
+ DESCR("length (possibly compressed) of varlena types");
+ 
  
  /*
   * Symbolic values for provolatile column: these indicate whether the result
diff -Nacr ./src/include/utils/builtins.h.orig ./src/include/utils/builtins.h
*** ./src/include/utils/builtins.h.orig	Fri May 27 12:57:49 2005
--- ./src/include/utils/builtins.h	Mon Jun 20 15:59:09 2005
***************
*** 601,606 ****
--- 601,607 ----
  extern Datum byteapos(PG_FUNCTION_ARGS);
  extern Datum bytea_substr(PG_FUNCTION_ARGS);
  extern Datum bytea_substr_no_len(PG_FUNCTION_ARGS);
+ extern Datum pg_datum_length(PG_FUNCTION_ARGS);
  
  /* version.c */
  extern Datum pgsql_version(PG_FUNCTION_ARGS);