Change the UNKNOWN type to have an internal representation matching

cstring, rather than text, so as to eliminate useless conversions
inside the parser.  Per recent discussion.

src/backend/parser/parse_coerce.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_coerce.c,v 2.129 2005/05/29 18:24:13 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_coerce.c,v 2.130 2005/05/30 01:20:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -168,8 +168,11 @@ coerce_type(ParseState *pstate, Node *node,
 
 		if (!con->constisnull)
 		{
-			char	   *val = DatumGetCString(DirectFunctionCall1(unknownout,
-													   con->constvalue));
+			/*
+			 * We assume here that UNKNOWN's internal representation is the
+			 * same as CSTRING
+			 */
+			char	   *val = DatumGetCString(con->constvalue);
 
 			/*
 			 * We pass typmod -1 to the input routine, primarily because
@@ -183,7 +186,6 @@ coerce_type(ParseState *pstate, Node *node,
 			 * ugly...
 			 */
 			newcon->constvalue = stringTypeDatum(targetType, val, -1);
-			pfree(val);
 		}
 
 		result = (Node *) newcon;

src/backend/parser/parse_node.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_node.c,v 1.88 2005/04/23 18:35:12 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_node.c,v 1.89 2005/05/30 01:20:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -271,8 +271,8 @@ transformArraySubscripts(ParseState *pstate,
  *	have to guess what type is wanted.
  *
  *	For string literals we produce a constant of type UNKNOWN ---- whose
- *	representation is the same as text, but it indicates to later type
- *	resolution that we're not sure that it should be considered text.
+ *	representation is the same as cstring, but it indicates to later type
+ *	resolution that we're not sure yet what type it should be considered.
  *	Explicit "NULL" constants are also typed as UNKNOWN.
  *
  *	For integers and floats we produce int4, int8, or numeric depending
@@ -341,11 +341,14 @@ make_const(Value *value)
 			break;
 
 		case T_String:
-			val = DirectFunctionCall1(unknownin,
-									  CStringGetDatum(strVal(value)));
+			/*
+			 * We assume here that UNKNOWN's internal representation is the
+			 * same as CSTRING
+			 */
+			val = CStringGetDatum(strVal(value));
 
 			typeid = UNKNOWNOID;	/* will be coerced later */
-			typelen = -1;		/* variable len */
+			typelen = -2;			/* cstring-style varwidth type */
 			typebyval = false;
 			break;
 
@@ -362,7 +365,7 @@ make_const(Value *value)
 		case T_Null:
 			/* return a null const */
 			con = makeConst(UNKNOWNOID,
-							-1,
+							-2,
 							(Datum) 0,
 							true,
 							false);

src/backend/utils/adt/varlena.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.122 2005/05/27 00:57:49 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.123 2005/05/30 01:20:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -330,18 +330,10 @@ textsend(PG_FUNCTION_ARGS)
 Datum
 unknownin(PG_FUNCTION_ARGS)
 {
-	char	   *inputStr = PG_GETARG_CSTRING(0);
-	unknown    *result;
-	int			len;
+	char	   *str = PG_GETARG_CSTRING(0);
 
-	len = strlen(inputStr) + VARHDRSZ;
-
-	result = (unknown *) palloc(len);
-	VARATT_SIZEP(result) = len;
-
-	memcpy(VARDATA(result), inputStr, len - VARHDRSZ);
-
-	PG_RETURN_UNKNOWN_P(result);
+	/* representation is same as cstring */
+	PG_RETURN_CSTRING(pstrdup(str));
 }
 
 /*
@@ -350,16 +342,10 @@ unknownin(PG_FUNCTION_ARGS)
 Datum
 unknownout(PG_FUNCTION_ARGS)
 {
-	unknown    *t = PG_GETARG_UNKNOWN_P(0);
-	int			len;
-	char	   *result;
+	/* representation is same as cstring */
+	char	   *str = PG_GETARG_CSTRING(0);
 
-	len = VARSIZE(t) - VARHDRSZ;
-	result = (char *) palloc(len + 1);
-	memcpy(result, VARDATA(t), len);
-	result[len] = '\0';
-
-	PG_RETURN_CSTRING(result);
+	PG_RETURN_CSTRING(pstrdup(str));
 }
 
 /*
@@ -369,28 +355,27 @@ Datum
 unknownrecv(PG_FUNCTION_ARGS)
 {
 	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
-	unknown    *result;
+	char	   *str;
 	int			nbytes;
 
-	nbytes = buf->len - buf->cursor;
-	result = (unknown *) palloc(nbytes + VARHDRSZ);
-	VARATT_SIZEP(result) = nbytes + VARHDRSZ;
-	pq_copymsgbytes(buf, VARDATA(result), nbytes);
-	PG_RETURN_UNKNOWN_P(result);
+	str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
+	/* representation is same as cstring */
+	PG_RETURN_CSTRING(str);
 }
 
 /*
  *		unknownsend			- converts unknown to binary format
- *
- * This is a special case: just copy the input, since it's
- * effectively the same format as bytea
  */
 Datum
 unknownsend(PG_FUNCTION_ARGS)
 {
-	unknown    *vlena = PG_GETARG_UNKNOWN_P_COPY(0);
+	/* representation is same as cstring */
+	char	   *str = PG_GETARG_CSTRING(0);
+	StringInfoData buf;
 
-	PG_RETURN_UNKNOWN_P(vlena);
+	pq_begintypsend(&buf);
+	pq_sendtext(&buf, str, strlen(str));
+	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
 }