Initial SQL/XML support: xml data type and initial set of functions.

15 files changed, 1566 insertions, 25 deletions

diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index 1dbef5f15c9..10b02b4a3ec 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.199 2006/11/17 16:46:27 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.200 2006/12/21 16:05:13 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -52,6 +52,7 @@
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/typcache.h"
+#include "utils/xml.h"
 
 
 /* static function decls */
@@ -119,6 +120,8 @@ static Datum ExecEvalMinMax(MinMaxExprState *minmaxExpr,
 static Datum ExecEvalNullIf(FuncExprState *nullIfExpr,
 			   ExprContext *econtext,
 			   bool *isNull, ExprDoneCond *isDone);
+static Datum ExecEvalXml(XmlExprState *xmlExpr, ExprContext *econtext,
+						 bool *isNull, ExprDoneCond *isDone);
 static Datum ExecEvalNullTest(NullTestState *nstate,
 				 ExprContext *econtext,
 				 bool *isNull, ExprDoneCond *isDone);
@@ -2878,6 +2881,120 @@ ExecEvalBooleanTest(GenericExprState *bstate,
 	}
 }
 
+/* ----------------------------------------------------------------
+ *		ExecEvalXml
+ * ----------------------------------------------------------------
+ */
+ 
+static Datum
+ExecEvalXml(XmlExprState *xmlExpr, ExprContext *econtext,
+			bool *isNull, ExprDoneCond *isDone)
+{
+	StringInfoData 	buf;
+	bool 			isnull;
+	ListCell 	   *arg;
+	text 		   *result = NULL;
+	int 			len;
+
+	initStringInfo(&buf);
+
+	*isNull = false;
+
+	if (isDone)
+		*isDone = ExprSingleResult;
+
+	switch (xmlExpr->op)
+	{
+		case IS_XMLCONCAT:
+			*isNull = true;
+
+			foreach(arg, xmlExpr->args)
+			{
+				ExprState 	*e = (ExprState *) lfirst(arg);
+				Datum 		value = ExecEvalExpr(e, econtext, &isnull, NULL);
+
+				if (!isnull)
+				{
+					appendStringInfoString(&buf, DatumGetCString(OidFunctionCall1(xmlExpr->arg_typeout, value)));
+					*isNull = false;
+				}
+			}
+			break;
+
+		case IS_XMLELEMENT:
+			{
+				int state = 0, i = 0;
+				appendStringInfo(&buf, "<%s", xmlExpr->name);
+				foreach(arg, xmlExpr->named_args)
+				{
+					GenericExprState *gstate = (GenericExprState *) lfirst(arg);
+					Datum value = ExecEvalExpr(gstate->arg, econtext, &isnull, NULL);
+					if (!isnull)
+					{
+						char *outstr = DatumGetCString(OidFunctionCall1(xmlExpr->named_args_tcache[i], value));
+						appendStringInfo(&buf, " %s=\"%s\"", xmlExpr->named_args_ncache[i], outstr);
+						pfree(outstr);
+					}
+					i++;
+				}
+				if (xmlExpr->args)
+				{
+					ExprState 	*expr = linitial(xmlExpr->args);
+					Datum 		value = ExecEvalExpr(expr, econtext, &isnull, NULL);
+
+					if (!isnull)
+					{
+						char *outstr = DatumGetCString(OidFunctionCall1(xmlExpr->arg_typeout, value));
+						if (state == 0)
+						{
+							appendStringInfoChar(&buf, '>');
+							state = 1;
+						}
+						appendStringInfo(&buf, "%s", outstr);
+						pfree(outstr);
+					}
+			 	}
+
+				if (state == 0)
+					appendStringInfo(&buf, "/>");
+			 	else if (state == 1)
+					appendStringInfo(&buf, "</%s>", xmlExpr->name);		
+
+			}
+			break;
+
+		case IS_XMLFOREST:
+			{
+				/* only if all argumets are null returns null */
+				int i = 0; 
+				*isNull = true;
+				foreach(arg, xmlExpr->named_args)
+			 	{
+					GenericExprState *gstate = (GenericExprState *) lfirst(arg);
+					Datum value = ExecEvalExpr(gstate->arg, econtext, &isnull, NULL);
+					if (!isnull)
+					{
+						char *outstr = DatumGetCString(OidFunctionCall1(xmlExpr->named_args_tcache[i], value));
+						appendStringInfo(&buf, "<%s>%s</%s>", xmlExpr->named_args_ncache[i], outstr, xmlExpr->named_args_ncache[i]);
+						pfree(outstr);
+						*isNull = false;
+					}
+					i += 1;
+				}		
+			}
+			break;
+		default:
+			break;
+	}
+
+	len = buf.len + VARHDRSZ;
+	result = palloc(len);
+	VARATT_SIZEP(result) = len;
+	memcpy(VARDATA(result), buf.data, buf.len);
+	pfree(buf.data);
+	PG_RETURN_TEXT_P(result);
+}
+
 /*
  * ExecEvalCoerceToDomain
  *
@@ -3668,6 +3785,64 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				state = (ExprState *) mstate;
 			}
 			break;
+		case T_XmlExpr:
+			{
+				List			*outlist; 
+				ListCell		*arg;
+				XmlExpr			*xexpr = (XmlExpr *) node;
+				XmlExprState	*xstate = makeNode(XmlExprState);
+				int				i = 0; 
+				Oid				typeout;
+		
+				xstate->name = xexpr->name;
+								
+				xstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalXml;
+				xstate->op = xexpr->op;
+				
+				outlist = NIL;
+				if (xexpr->named_args)
+				{
+					xstate->named_args_tcache = (Oid *) palloc(list_length(xexpr->named_args) * sizeof(int));
+					xstate->named_args_ncache = (char **) palloc(list_length(xexpr->named_args) * sizeof(char *));
+					
+					i = 0;
+					foreach(arg, xexpr->named_args)
+					{
+						bool		tpisvarlena;
+						Expr		*e = (Expr *) lfirst(arg);
+						ExprState	*estate = ExecInitExpr(e, parent);
+						TargetEntry	*tle;
+						outlist = lappend(outlist, estate);					
+						tle = (TargetEntry *) ((GenericExprState *) estate)->xprstate.expr;
+						getTypeOutputInfo(exprType((Node *)tle->expr), &typeout, &tpisvarlena);
+						xstate->named_args_ncache[i] = tle->resname;
+						xstate->named_args_tcache[i] = typeout;
+						i++;
+					}	
+				}
+				else
+				{
+					xstate->named_args_tcache = NULL;
+					xstate->named_args_ncache = NULL;
+				}
+				xstate->named_args = outlist;
+
+				outlist = NIL;				
+				foreach(arg, xexpr->args)
+				{
+					bool 		tpisvarlena;
+					ExprState 	*estate;
+					Expr 		*e = (Expr *) lfirst(arg);
+					getTypeOutputInfo(exprType((Node *)e), &typeout, &tpisvarlena);
+					estate = ExecInitExpr(e, parent);
+					outlist = lappend(outlist, estate);
+				}
+				xstate->arg_typeout = typeout;
+				xstate->args = outlist;
+				
+				state = (ExprState *) xstate;
+			}
+			break;
 		case T_NullIfExpr:
 			{
 				NullIfExpr *nullifexpr = (NullIfExpr *) node;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 5047dc8ad7b..3bb95b658d1 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.354 2006/12/10 22:13:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.355 2006/12/21 16:05:13 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1137,6 +1137,22 @@ _copyBooleanTest(BooleanTest *from)
 }
 
 /*
+ * _copyXmlExpr
+ */
+static XmlExpr *
+_copyXmlExpr(XmlExpr *from)
+{
+	XmlExpr *newnode = makeNode(XmlExpr);
+
+	COPY_SCALAR_FIELD(op);
+	COPY_STRING_FIELD(name);
+	COPY_NODE_FIELD(named_args);
+	COPY_NODE_FIELD(args);
+
+	return newnode;
+}
+
+/*
  * _copyCoerceToDomain
  */
 static CoerceToDomain *
@@ -2966,6 +2982,9 @@ copyObject(void *from)
 		case T_BooleanTest:
 			retval = _copyBooleanTest(from);
 			break;
+		case T_XmlExpr:
+			retval = _copyXmlExpr(from);
+			break;
 		case T_CoerceToDomain:
 			retval = _copyCoerceToDomain(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index e341b74f3e6..ef21e67fafb 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.288 2006/12/10 22:13:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.289 2006/12/21 16:05:13 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -496,6 +496,17 @@ _equalBooleanTest(BooleanTest *a, BooleanTest *b)
 }
 
 static bool
+_equalXmlExpr(XmlExpr *a, XmlExpr *b)
+{
+	COMPARE_SCALAR_FIELD(op);
+	COMPARE_STRING_FIELD(name);
+	COMPARE_NODE_FIELD(named_args);
+	COMPARE_NODE_FIELD(args);
+
+	return true;
+}
+
+static bool
 _equalCoerceToDomain(CoerceToDomain *a, CoerceToDomain *b)
 {
 	COMPARE_NODE_FIELD(arg);
@@ -1968,6 +1979,9 @@ equal(void *a, void *b)
 		case T_BooleanTest:
 			retval = _equalBooleanTest(a, b);
 			break;
+		case T_XmlExpr:
+			retval = _equalXmlExpr(a, b);
+			break;
 		case T_CoerceToDomain:
 			retval = _equalCoerceToDomain(a, b);
 			break;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index daeb3fe872d..5ddf60dbbb1 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.286 2006/12/10 22:13:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.287 2006/12/21 16:05:13 petere Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -921,6 +921,17 @@ _outBooleanTest(StringInfo str, BooleanTest *node)
 }
 
 static void
+_outXmlExpr(StringInfo str, XmlExpr *node)
+{
+	WRITE_NODE_TYPE("XMLEXPR");
+	
+	WRITE_ENUM_FIELD(op, XmlExprOp);
+	WRITE_STRING_FIELD(name);
+	WRITE_NODE_FIELD(named_args);
+	WRITE_NODE_FIELD(args);
+}
+
+static void
 _outCoerceToDomain(StringInfo str, CoerceToDomain *node)
 {
 	WRITE_NODE_TYPE("COERCETODOMAIN");
@@ -2019,6 +2030,9 @@ _outNode(StringInfo str, void *obj)
 			case T_BooleanTest:
 				_outBooleanTest(str, obj);
 				break;
+			case T_XmlExpr:
+				_outXmlExpr(str, obj);
+				break;
 			case T_CoerceToDomain:
 				_outCoerceToDomain(str, obj);
 				break;
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index df0a2170272..689cef3edf2 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.196 2006/12/10 22:13:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.197 2006/12/21 16:05:13 petere Exp $
  *
  * NOTES
  *	  Path and Plan nodes do not have any readfuncs support, because we
@@ -765,6 +765,22 @@ _readBooleanTest(void)
 }
 
 /*
+ * _readXmlExpr
+ */
+static XmlExpr *
+_readXmlExpr(void)
+{
+	READ_LOCALS(XmlExpr);
+
+	READ_ENUM_FIELD(op, XmlExprOp);
+	READ_STRING_FIELD(name);
+	READ_NODE_FIELD(named_args);
+	READ_NODE_FIELD(args);
+
+	READ_DONE();
+}
+
+/*
  * _readCoerceToDomain
  */
 static CoerceToDomain *
@@ -1014,6 +1030,8 @@ parseNodeString(void)
 		return_value = _readNullTest();
 	else if (MATCH("BOOLEANTEST", 11))
 		return_value = _readBooleanTest();
+	else if (MATCH("XMLEXPR", 7))
+		return_value = _readXmlExpr();
 	else if (MATCH("COERCETODOMAIN", 14))
 		return_value = _readCoerceToDomain();
 	else if (MATCH("COERCETODOMAINVALUE", 19))
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 3800228398e..73ad926418f 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.223 2006/10/25 22:11:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.224 2006/12/21 16:05:13 petere Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -559,6 +559,8 @@ expression_returns_set_walker(Node *node, void *context)
 		return false;
 	if (IsA(node, NullIfExpr))
 		return false;
+	if (IsA(node, XmlExpr))
+		return false;
 
 	return expression_tree_walker(node, expression_returns_set_walker,
 								  context);
@@ -876,6 +878,8 @@ contain_nonstrict_functions_walker(Node *node, void *context)
 		return true;
 	if (IsA(node, BooleanTest))
 		return true;
+	if (IsA(node, XmlExpr))
+		return true;
 	return expression_tree_walker(node, contain_nonstrict_functions_walker,
 								  context);
 }
@@ -3334,6 +3338,16 @@ expression_tree_walker(Node *node,
 			return walker(((NullTest *) node)->arg, context);
 		case T_BooleanTest:
 			return walker(((BooleanTest *) node)->arg, context);
+		case T_XmlExpr:
+			{
+				XmlExpr *xexpr = (XmlExpr *) node;
+				
+				if (walker(xexpr->named_args, context))
+					return true;
+				if (walker(xexpr->args, context))
+					return true;
+			}
+			break;
 		case T_CoerceToDomain:
 			return walker(((CoerceToDomain *) node)->arg, context);
 		case T_TargetEntry:
@@ -3857,6 +3871,17 @@ expression_tree_mutator(Node *node,
 				return (Node *) newnode;
 			}
 			break;
+		case T_XmlExpr:
+			{
+				XmlExpr *xexpr = (XmlExpr *) node;
+				XmlExpr *newnode;
+
+				FLATCOPY(newnode, xexpr, XmlExpr);
+				MUTATE(newnode->named_args, xexpr->named_args, List *);
+				MUTATE(newnode->args, xexpr->args, List *);
+				return (Node *) newnode;
+			}
+			break;
 		case T_NullIfExpr:
 			{
 				NullIfExpr *expr = (NullIfExpr *) node;
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index c90743a1017..cc400407363 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.568 2006/11/05 22:42:09 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.569 2006/12/21 16:05:14 petere Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -106,6 +106,7 @@ static void insertSelectOptions(SelectStmt *stmt,
 static Node *makeSetOp(SetOperation op, bool all, Node *larg, Node *rarg);
 static Node *doNegate(Node *n, int location);
 static void doNegateFloat(Value *v);
+static Node *makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args);
 
 %}
 
@@ -345,6 +346,11 @@ static void doNegateFloat(Value *v);
 %type <str>		OptTableSpace OptConsTableSpace OptTableSpaceOwner
 %type <list>	opt_check_option
 
+%type <target>	xml_attribute_el
+%type <list>	xml_attribute_list xml_attributes
+%type <node>	xml_root_version
+%type <ival>	opt_xml_root_standalone document_or_content xml_whitespace_option
+
 
 /*
  * If you make any token changes, update the keyword table in
@@ -365,13 +371,13 @@ static void doNegateFloat(Value *v);
 	CHARACTER CHARACTERISTICS CHECK CHECKPOINT CLASS CLOSE
 	CLUSTER COALESCE COLLATE COLUMN COMMENT COMMIT
 	COMMITTED CONCURRENTLY CONNECTION CONSTRAINT CONSTRAINTS
-	CONVERSION_P CONVERT COPY CREATE CREATEDB
+	CONTENT CONVERSION_P CONVERT COPY CREATE CREATEDB
 	CREATEROLE CREATEUSER CROSS CSV CURRENT_DATE CURRENT_ROLE CURRENT_TIME
 	CURRENT_TIMESTAMP CURRENT_USER CURSOR CYCLE
 
 	DATABASE DAY_P DEALLOCATE DEC DECIMAL_P DECLARE DEFAULT DEFAULTS
 	DEFERRABLE DEFERRED DEFINER DELETE_P DELIMITER DELIMITERS
-	DESC DISABLE_P DISTINCT DO DOMAIN_P DOUBLE_P DROP
+	DESC DISABLE_P DISTINCT DO DOCUMENT DOMAIN_P DOUBLE_P DROP
 
 	EACH ELSE ENABLE_P ENCODING ENCRYPTED END_P ESCAPE EXCEPT EXCLUDING
 	EXCLUSIVE EXECUTE EXISTS EXPLAIN EXTERNAL EXTRACT
@@ -398,7 +404,7 @@ static void doNegateFloat(Value *v);
 
 	MATCH MAXVALUE MINUTE_P MINVALUE MODE MONTH_P MOVE
 
-	NAMES NATIONAL NATURAL NCHAR NEW NEXT NO NOCREATEDB
+	NAME NAMES NATIONAL NATURAL NCHAR NEW NEXT NO NOCREATEDB
 	NOCREATEROLE NOCREATEUSER NOINHERIT NOLOGIN_P NONE NOSUPERUSER
 	NOT NOTHING NOTIFY NOTNULL NOWAIT NULL_P NULLIF NUMERIC
 
@@ -417,8 +423,8 @@ static void doNegateFloat(Value *v);
 
 	SAVEPOINT SCHEMA SCROLL SECOND_P SECURITY SELECT SEQUENCE
 	SERIALIZABLE SESSION SESSION_USER SET SETOF SHARE
-	SHOW SIMILAR SIMPLE SMALLINT SOME STABLE START STATEMENT
-	STATISTICS STDIN STDOUT STORAGE STRICT_P SUBSTRING SUPERUSER_P SYMMETRIC
+	SHOW SIMILAR SIMPLE SMALLINT SOME STABLE STANDALONE START STATEMENT
+	STATISTICS STDIN STDOUT STORAGE STRICT_P STRIP SUBSTRING SUPERUSER_P SYMMETRIC
 	SYSID SYSTEM_P
 
 	TABLE TABLESPACE TEMP TEMPLATE TEMPORARY THEN TIME TIMESTAMP
@@ -428,12 +434,15 @@ static void doNegateFloat(Value *v);
 	UNCOMMITTED UNENCRYPTED UNION UNIQUE UNKNOWN UNLISTEN UNTIL
 	UPDATE USER USING
 
-	VACUUM VALID VALIDATOR VALUES VARCHAR VARYING
-	VERBOSE VIEW VOLATILE
+	VACUUM VALID VALIDATOR VALUE VALUES VARCHAR VARYING
+	VERBOSE VERSION VIEW VOLATILE
+
+	WHEN WHERE WHITESPACE WITH WITHOUT WORK WRITE
 
-	WHEN WHERE WITH WITHOUT WORK WRITE
+	XMLATTRIBUTES XMLCONCAT XMLELEMENT XMLFOREST XMLPARSE
+	XMLPI XMLROOT XMLSERIALIZE
 
-	YEAR_P
+	YEAR_P YES
 
 	ZONE
 
@@ -484,6 +493,7 @@ static void doNegateFloat(Value *v);
  * left-associativity among the JOIN rules themselves.
  */
 %left		JOIN CROSS LEFT FULL RIGHT INNER_P NATURAL
+%right		PRESERVE STRIP
 %%
 
 /*
@@ -7868,6 +7878,146 @@ func_expr:	func_name '(' ')'
 					v->op = IS_LEAST;
 					$$ = (Node *)v;
 				}
+			| XMLCONCAT '(' expr_list ')'
+				{		
+					$$ = makeXmlExpr(IS_XMLCONCAT, NULL, NULL, $3);
+				}
+			| XMLELEMENT '(' NAME ColLabel ')'
+				{
+					$$ = makeXmlExpr(IS_XMLELEMENT, $4, NULL, NULL);
+				}
+			| XMLELEMENT '(' NAME ColLabel ',' xml_attributes ')'
+				{
+					$$ = makeXmlExpr(IS_XMLELEMENT, $4, $6, NULL);
+				}
+			| XMLELEMENT '(' NAME ColLabel ',' expr_list ')'
+				{
+					$$ = makeXmlExpr(IS_XMLELEMENT, $4, NULL, $6);
+				}
+			| XMLELEMENT '(' NAME ColLabel ',' xml_attributes ',' expr_list ')'
+				{
+					$$ = makeXmlExpr(IS_XMLELEMENT, $4, $6, $8);
+				}
+			| XMLFOREST '(' xml_attribute_list ')'
+				{
+					$$ = makeXmlExpr(IS_XMLFOREST, NULL, $3, NULL);
+				}
+			| XMLPARSE '(' document_or_content a_expr xml_whitespace_option ')'
+				{
+					FuncCall *n = makeNode(FuncCall);
+					n->funcname = SystemFuncName("xmlparse");
+					n->args = list_make3(makeBoolAConst($3 == DOCUMENT), $4, makeBoolAConst($5 == PRESERVE));
+					n->agg_star = FALSE;
+					n->agg_distinct = FALSE;
+					n->location = @1;
+					$$ = (Node *)n;
+				}
+			| XMLPI '(' NAME ColLabel ')'
+				{
+					FuncCall *n = makeNode(FuncCall);
+					n->funcname = SystemFuncName("xmlpi");
+					n->args = list_make1(makeStringConst($4, NULL));
+					n->agg_star = FALSE;
+					n->agg_distinct = FALSE;
+					n->location = @1;
+					$$ = (Node *)n;
+				}
+			| XMLPI '(' NAME ColLabel ',' a_expr ')'
+				{
+					FuncCall *n = makeNode(FuncCall);
+					n->funcname = SystemFuncName("xmlpi");
+					n->args = list_make2(makeStringConst($4, NULL), $6);
+					n->agg_star = FALSE;
+					n->agg_distinct = FALSE;
+					n->location = @1;
+					$$ = (Node *)n;
+				}
+			| XMLROOT '(' a_expr ',' xml_root_version opt_xml_root_standalone ')'
+				{
+					FuncCall *n = makeNode(FuncCall);
+					Node *ver;
+					A_Const *sa;
+
+					if ($5)
+						ver = $5;
+					else
+					{
+						A_Const *val;
+
+						val = makeNode(A_Const);
+						val->val.type = T_Null;
+						ver = (Node *) val;
+					}
+
+					if ($6)
+						sa = makeBoolAConst($6 == 1);
+					else
+					{
+						sa = makeNode(A_Const);
+						sa->val.type = T_Null;
+					}
+
+					n->funcname = SystemFuncName("xmlroot");
+					n->args = list_make3($3, ver, sa);
+					n->agg_star = FALSE;
+					n->agg_distinct = FALSE;
+					n->location = @1;
+					$$ = (Node *)n;
+				}
+			| XMLSERIALIZE '(' document_or_content a_expr AS Typename ')'
+				{
+					/*
+					 * FIXME: This should be made distinguishable from
+					 * CAST (for reverse compilation at least).
+					 */
+					$$ = makeTypeCast($4, $6);
+				}
+		;
+
+/*
+ * SQL/XML support
+ */
+xml_root_version: VERSION a_expr	{ $$ = $2; }
+			| VERSION NO VALUE		{ $$ = NULL; }
+		;
+
+opt_xml_root_standalone: ',' STANDALONE YES	{ $$ = 1; }
+			| ',' STANDALONE NO				{ $$ = -1; }
+			| ',' STANDALONE NO VALUE		{ $$ = 0; }
+			| /*EMPTY*/						{ $$ = 0; }
+		;
+
+xml_attributes: XMLATTRIBUTES '(' xml_attribute_list ')' { $$ = $3; }
+		;
+
+xml_attribute_list:	xml_attribute_el					{ $$ = list_make1($1); }
+			| xml_attribute_list ',' xml_attribute_el	{ $$ = lappend($1, $3); }
+		;
+
+xml_attribute_el: a_expr AS ColLabel
+				{
+					$$ = makeNode(ResTarget);
+					$$->name = $3;
+					$$->indirection = NULL;
+					$$->val = (Node *) $1;
+
+				}
+			| a_expr
+				{
+					$$ = makeNode(ResTarget);
+					$$->name = NULL;
+					$$->indirection = NULL;
+					$$->val = (Node *) $1;				
+				}
+		;
+
+document_or_content: DOCUMENT { $$ = DOCUMENT; }
+			| CONTENT { $$ = CONTENT; }
+		;
+
+xml_whitespace_option: PRESERVE WHITESPACE { $$ = PRESERVE; }
+			| STRIP WHITESPACE { $$ = STRIP; }
+			| /*EMPTY*/ { $$ = STRIP; }
 		;
 
 /*
@@ -8562,6 +8712,7 @@ unreserved_keyword:
 			| CONCURRENTLY
 			| CONNECTION
 			| CONSTRAINTS
+			| CONTENT
 			| CONVERSION_P
 			| COPY
 			| CREATEDB
@@ -8581,6 +8732,7 @@ unreserved_keyword:
 			| DELIMITER
 			| DELIMITERS
 			| DISABLE_P
+			| DOCUMENT
 			| DOMAIN_P
 			| DOUBLE_P
 			| DROP
@@ -8640,6 +8792,7 @@ unreserved_keyword:
 			| MODE
 			| MONTH_P
 			| MOVE
+			| NAME
 			| NAMES
 			| NEXT
 			| NO
@@ -8700,12 +8853,14 @@ unreserved_keyword:
 			| SHOW
 			| SIMPLE
 			| STABLE
+			| STANDALONE
 			| START
 			| STATEMENT
 			| STATISTICS
 			| STDIN
 			| STDOUT
 			| STORAGE
+			| STRIP
 			| SUPERUSER_P
 			| SYSID
 			| SYSTEM_P
@@ -8729,13 +8884,17 @@ unreserved_keyword:
 			| VALID
 			| VALIDATOR
 			| VARYING
+			| VERSION
 			| VIEW
+			| VALUE
 			| VOLATILE
+			| WHITESPACE
 			| WITH
 			| WITHOUT
 			| WORK
 			| WRITE
 			| YEAR_P
+			| YES
 			| ZONE
 		;
 
@@ -8788,6 +8947,14 @@ col_name_keyword:
 			| TRIM
 			| VALUES
 			| VARCHAR
+			| XMLATTRIBUTES
+			| XMLELEMENT
+			| XMLCONCAT
+			| XMLFOREST
+			| XMLPARSE
+			| XMLPI
+			| XMLROOT
+			| XMLSERIALIZE
 		;
 
 /* Function identifier --- keywords that can be function names.
@@ -9322,6 +9489,17 @@ doNegateFloat(Value *v)
 	}
 }
 
+static Node *
+makeXmlExpr(XmlExprOp op, char *name, List *named_args, List *args)
+{
+	XmlExpr *x = makeNode(XmlExpr);
+	x->op = op;
+	x->name = name;
+	x->named_args = named_args;
+	x->args = args;
+	return (Node *) x;
+}
+
 /*
  * Must undefine base_yylex before including scan.c, since we want it
  * to create the function base_yylex not filtered_base_yylex.
diff --git a/src/backend/parser/keywords.c b/src/backend/parser/keywords.c
index 50fd3aac405..b5e49e955fc 100644
--- a/src/backend/parser/keywords.c
+++ b/src/backend/parser/keywords.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.177 2006/10/07 21:51:02 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.178 2006/12/21 16:05:14 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -89,6 +89,7 @@ static const ScanKeyword ScanKeywords[] = {
 	{"connection", CONNECTION},
 	{"constraint", CONSTRAINT},
 	{"constraints", CONSTRAINTS},
+	{"content", CONTENT},
 	{"conversion", CONVERSION_P},
 	{"convert", CONVERT},
 	{"copy", COPY},
@@ -123,6 +124,7 @@ static const ScanKeyword ScanKeywords[] = {
 	{"disable", DISABLE_P},
 	{"distinct", DISTINCT},
 	{"do", DO},
+	{"document", DOCUMENT},
 	{"domain", DOMAIN_P},
 	{"double", DOUBLE_P},
 	{"drop", DROP},
@@ -218,6 +220,7 @@ static const ScanKeyword ScanKeywords[] = {
 	{"mode", MODE},
 	{"month", MONTH_P},
 	{"move", MOVE},
+	{"name", NAME},
 	{"names", NAMES},
 	{"national", NATIONAL},
 	{"natural", NATURAL},
@@ -314,6 +317,7 @@ static const ScanKeyword ScanKeywords[] = {
 	{"smallint", SMALLINT},
 	{"some", SOME},
 	{"stable", STABLE},
+	{"standalone", STANDALONE},
 	{"start", START},
 	{"statement", STATEMENT},
 	{"statistics", STATISTICS},
@@ -321,6 +325,7 @@ static const ScanKeyword ScanKeywords[] = {
 	{"stdout", STDOUT},
 	{"storage", STORAGE},
 	{"strict", STRICT_P},
+	{"strip", STRIP},
 	{"substring", SUBSTRING},
 	{"superuser", SUPERUSER_P},
 	{"symmetric", SYMMETRIC},
@@ -357,19 +362,31 @@ static const ScanKeyword ScanKeywords[] = {
 	{"vacuum", VACUUM},
 	{"valid", VALID},
 	{"validator", VALIDATOR},
+	{"value", VALUE},
 	{"values", VALUES},
 	{"varchar", VARCHAR},
 	{"varying", VARYING},
 	{"verbose", VERBOSE},
+	{"version", VERSION},
 	{"view", VIEW},
 	{"volatile", VOLATILE},
 	{"when", WHEN},
 	{"where", WHERE},
+	{"whitespace", WHITESPACE},
 	{"with", WITH},
 	{"without", WITHOUT},
 	{"work", WORK},
 	{"write", WRITE},
+	{"xmlattributes", XMLATTRIBUTES},
+	{"xmlconcat", XMLCONCAT},
+	{"xmlelement", XMLELEMENT},
+	{"xmlforest", XMLFOREST},
+	{"xmlparse", XMLPARSE},
+	{"xmlpi", XMLPI},
+	{"xmlroot", XMLROOT},
+	{"xmlserialize", XMLSERIALIZE},
 	{"year", YEAR_P},
+	{"yes", YES},
 	{"zone", ZONE},
 };
 
diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
index 2a468c68271..5670ed4fe74 100644
--- a/src/backend/parser/parse_coerce.c
+++ b/src/backend/parser/parse_coerce.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_coerce.c,v 2.147 2006/12/10 22:13:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_coerce.c,v 2.148 2006/12/21 16:05:14 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -919,6 +919,46 @@ coerce_to_bigint(ParseState *pstate, Node *node,
 	return node;
 }
 
+/*
+ * coerce_to_xml()
+ *		Coerce an argument of a construct that requires xml input.
+ *		Also check that input is not a set.
+ *
+ * Returns the possibly-transformed node tree.
+ *
+ * As with coerce_type, pstate may be NULL if no special unknown-Param
+ * processing is wanted.
+ */
+Node *
+coerce_to_xml(ParseState *pstate, Node *node,
+				 const char *constructName)
+{
+	Oid			inputTypeId = exprType(node);
+
+	if (inputTypeId != XMLOID)
+	{
+		node = coerce_to_target_type(pstate, node, inputTypeId,
+									 XMLOID, -1,
+									 COERCION_ASSIGNMENT,
+									 COERCE_IMPLICIT_CAST);
+		if (node == NULL)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+			/* translator: first %s is name of a SQL construct, eg LIMIT */
+					 errmsg("argument of %s must be type xml, not type %s",
+							constructName, format_type_be(inputTypeId))));
+	}
+
+	if (expression_returns_set(node))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+		/* translator: %s is name of a SQL construct, eg LIMIT */
+				 errmsg("argument of %s must not return a set",
+						constructName)));
+
+	return node;
+}
+
 
 /* select_common_type()
  *		Determine the common supertype of a list of input expression types.
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index b1b6ea81456..234a15b6afb 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.199 2006/12/10 22:13:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_expr.c,v 1.200 2006/12/21 16:05:14 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -33,6 +33,7 @@
 #include "parser/parse_type.h"
 #include "utils/builtins.h"
 #include "utils/lsyscache.h"
+#include "utils/xml.h"
 
 
 bool		Transform_null_equals = false;
@@ -55,6 +56,7 @@ static Node *transformArrayExpr(ParseState *pstate, ArrayExpr *a);
 static Node *transformRowExpr(ParseState *pstate, RowExpr *r);
 static Node *transformCoalesceExpr(ParseState *pstate, CoalesceExpr *c);
 static Node *transformMinMaxExpr(ParseState *pstate, MinMaxExpr *m);
+static Node *transformXmlExpr(ParseState *pstate, XmlExpr *x);
 static Node *transformBooleanTest(ParseState *pstate, BooleanTest *b);
 static Node *transformColumnRef(ParseState *pstate, ColumnRef *cref);
 static Node *transformWholeRowRef(ParseState *pstate, char *schemaname,
@@ -232,6 +234,10 @@ transformExpr(ParseState *pstate, Node *expr)
 			result = transformBooleanTest(pstate, (BooleanTest *) expr);
 			break;
 
+		case T_XmlExpr:
+			result = transformXmlExpr(pstate, (XmlExpr *) expr);
+			break;
+
 			/*********************************************
 			 * Quietly accept node types that may be presented when we are
 			 * called on an already-transformed tree.
@@ -1409,6 +1415,56 @@ transformBooleanTest(ParseState *pstate, BooleanTest *b)
 	return (Node *) b;
 }
 
+static Node *
+transformXmlExpr(ParseState *pstate, XmlExpr *x)
+{
+	ListCell	*lc;
+	XmlExpr *newx = makeNode(XmlExpr);
+
+	newx->op = x->op;
+	if (x->name)
+		newx->name = map_sql_identifier_to_xml_name(x->name, false);
+	else
+		newx->name = NULL;
+
+	foreach(lc, x->named_args)
+	{
+		ResTarget 	*r = (ResTarget *) lfirst(lc);
+		Node 		*expr = transformExpr(pstate, r->val);
+		char 		*argname = NULL;
+
+		if (r->name)
+			argname = map_sql_identifier_to_xml_name(r->name, false);
+		else if (IsA(r->val, ColumnRef))
+			argname = map_sql_identifier_to_xml_name(FigureColname(r->val), true);
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 x->op == IS_XMLELEMENT
+					 ? errmsg("unnamed attribute value must be a column reference")
+					 : errmsg("unnamed element value must be a column reference")));
+
+		newx->named_args = lappend(newx->named_args, 
+								   makeTargetEntry((Expr *) expr, 0, argname, false)); 
+	}
+
+	foreach(lc, x->args)
+	{
+		Node	   *e = (Node *) lfirst(lc);
+		Node	   *newe;
+
+		newe = coerce_to_xml(pstate, transformExpr(pstate, e),
+							 (x->op == IS_XMLCONCAT 
+							  ? "XMLCONCAT"
+							  : (x->op == IS_XMLELEMENT
+								 ? "XMLELEMENT"
+								 : "XMLFOREST")));
+		newx->args = lappend(newx->args, newe);
+	}
+		
+	return (Node *) newx;
+}
+
 /*
  * Construct a whole-row reference to represent the notation "relation.*".
  *
@@ -1668,6 +1724,9 @@ exprType(Node *expr)
 		case T_BooleanTest:
 			type = BOOLOID;
 			break;
+		case T_XmlExpr:
+			type = XMLOID;
+			break;
 		case T_CoerceToDomain:
 			type = ((CoerceToDomain *) expr)->resulttype;
 			break;
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index bb4b065eebb..906d96e45c6 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_target.c,v 1.149 2006/10/04 00:29:56 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_target.c,v 1.150 2006/12/21 16:05:14 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1315,6 +1315,21 @@ FigureColnameInternal(Node *node, char **name)
 					return 2;
 			}
 			break;
+		case T_XmlExpr:
+			/* make SQL/XML functions act like a regular function */
+			switch (((XmlExpr*) node)->op)
+			{		
+				case IS_XMLCONCAT:
+					*name = "xmlconcat";
+					return 2;
+				case IS_XMLELEMENT:
+					*name = "xmlelement";
+					return 2;
+				case IS_XMLFOREST:
+					*name = "xmlforest";
+					return 2;
+			} 
+			break;
 		default:
 			break;
 	}
diff --git a/src/backend/utils/adt/Makefile b/src/backend/utils/adt/Makefile
index 5a1996c3439..11a03f31857 100644
--- a/src/backend/utils/adt/Makefile
+++ b/src/backend/utils/adt/Makefile
@@ -1,7 +1,7 @@
 #
 # Makefile for utils/adt
 #
-# $PostgreSQL: pgsql/src/backend/utils/adt/Makefile,v 1.60 2006/04/05 22:11:55 tgl Exp $
+# $PostgreSQL: pgsql/src/backend/utils/adt/Makefile,v 1.61 2006/12/21 16:05:15 petere Exp $
 #
 
 subdir = src/backend/utils/adt
@@ -25,7 +25,7 @@ OBJS = acl.o arrayfuncs.o array_userfuncs.o arrayutils.o bool.o \
 	tid.o timestamp.o varbit.o varchar.o varlena.o version.o xid.o \
 	network.o mac.o inet_net_ntop.o inet_net_pton.o \
 	ri_triggers.o pg_lzcompress.o pg_locale.o formatting.o \
-	ascii.o quote.o pgstatfuncs.o encode.o dbsize.o genfile.o
+	ascii.o quote.o pgstatfuncs.o encode.o dbsize.o genfile.o xml.o
 
 like.o: like.c like_match.c
 
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 9d9404bde4c..a99942010b6 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -2,7 +2,7 @@
  * ruleutils.c	- Functions to convert stored expressions/querytrees
  *				back to source text
  *
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.235 2006/11/10 22:59:29 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.236 2006/12/21 16:05:15 petere Exp $
  **********************************************************************/
 
 #include "postgres.h"
@@ -2988,6 +2988,7 @@ isSimpleNode(Node *node, Node *parentNode, int prettyFlags)
 		case T_CoalesceExpr:
 		case T_MinMaxExpr:
 		case T_NullIfExpr:
+		case T_XmlExpr:
 		case T_Aggref:
 		case T_FuncExpr:
 			/* function-like: name(..) or name[..] */
@@ -3096,6 +3097,7 @@ isSimpleNode(Node *node, Node *parentNode, int prettyFlags)
 				case T_CoalesceExpr:	/* own parentheses */
 				case T_MinMaxExpr:		/* own parentheses */
 				case T_NullIfExpr:		/* other separators */
+				case T_XmlExpr:			/* own parentheses */
 				case T_Aggref:	/* own parentheses */
 				case T_CaseExpr:		/* other separators */
 					return true;
@@ -3144,6 +3146,7 @@ isSimpleNode(Node *node, Node *parentNode, int prettyFlags)
 				case T_CoalesceExpr:	/* own parentheses */
 				case T_MinMaxExpr:		/* own parentheses */
 				case T_NullIfExpr:		/* other separators */
+				case T_XmlExpr:			/* own parentheses */
 				case T_Aggref:	/* own parentheses */
 				case T_CaseExpr:		/* other separators */
 					return true;
@@ -3845,6 +3848,28 @@ get_rule_expr(Node *node, deparse_context *context,
 			}
 			break;
 
+		case T_XmlExpr:
+			{
+				XmlExpr *xexpr = (XmlExpr *) node;
+
+				switch (xexpr->op)
+				{
+					case IS_XMLCONCAT:
+						appendStringInfo(buf, "XMLCONCAT(");
+						break;
+					case IS_XMLELEMENT:
+						appendStringInfo(buf, "XMLELEMENT(");
+						break;
+					case IS_XMLFOREST:
+						appendStringInfo(buf, "XMLFOREST(");
+						break;
+				}
+				get_rule_expr((Node *) xexpr->named_args, context, true);
+				get_rule_expr((Node *) xexpr->args, context, true);
+				appendStringInfoChar(buf, ')');
+			}
+			break;
+
 		case T_CoerceToDomain:
 			{
 				CoerceToDomain *ctest = (CoerceToDomain *) node;
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
new file mode 100644
index 00000000000..8997730fc8d
--- /dev/null
+++ b/src/backend/utils/adt/xml.c
@@ -0,0 +1,942 @@
+/*-------------------------------------------------------------------------
+ *
+ * xml.c
+ *	  XML data type support.
+ *
+ *
+ * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.1 2006/12/21 16:05:15 petere Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*
+ * Generally, XML type support is only available when libxml use was
+ * configured during the build.  But even if that is not done, the
+ * type and all the functions are available, but most of them will
+ * fail.  For one thing, this avoids having to manage variant catalog
+ * installations.  But it also has nice effects such as that you can
+ * dump a database containing XML type data even if the server is not
+ * linked with libxml.
+ */
+
+#include "postgres.h"
+
+#ifdef USE_LIBXML
+#include <libxml/chvalid.h>
+#include <libxml/parser.h>
+#include <libxml/tree.h>
+#include <libxml/uri.h>
+#include <libxml/xmlerror.h>
+#endif /* USE_LIBXML */
+
+#include "fmgr.h"
+#include "mb/pg_wchar.h"
+#include "nodes/execnodes.h"
+#include "utils/builtins.h"
+#include "utils/xml.h"
+
+
+#ifdef USE_LIBXML
+
+/*
+ * A couple of useful macros (similar to ones from libxml/parse.c)
+ */
+#define CMP4( s, c1, c2, c3, c4 ) \
+  ( ((unsigned char *) s)[ 0 ] == c1 && ((unsigned char *) s)[ 1 ] == c2 && \
+    ((unsigned char *) s)[ 2 ] == c3 && ((unsigned char *) s)[ 3 ] == c4 )
+#define CMP5( s, c1, c2, c3, c4, c5 ) \
+  ( CMP4( s, c1, c2, c3, c4 ) && ((unsigned char *) s)[ 4 ] == c5 )
+
+#define PG_XML_DEFAULT_URI "dummy.xml"
+#define XML_ERRBUF_SIZE 200
+
+
+static void 	xml_init(void);
+static void    *xml_palloc(size_t size);
+static void    *xml_repalloc(void *ptr, size_t size);
+static void 	xml_pfree(void *ptr);
+static char    *xml_pstrdup(const char *string);
+static void 	xml_ereport(int level, char *msg, void *ctxt);
+static void 	xml_errorHandler(void *ctxt, const char *msg, ...);
+static void 	xml_ereport_by_code(int level, char *msg, int errcode);
+static xmlChar *xml_text2xmlChar(text *in);
+static xmlDocPtr xml_parse(text *data, int opts, bool is_document);
+
+
+/* Global variables */
+/* taken from contrib/xml2 */
+/* FIXME: DO NOT USE global vars !!! */
+char	   *xml_errbuf;				/* per line error buffer */
+char	   *xml_errmsg = NULL;		/* overall error message */
+
+#endif /* USE_LIBXML */
+
+
+#define NO_XML_SUPPORT() ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("no XML support in this installation")))
+
+
+Datum
+xml_in(PG_FUNCTION_ARGS)
+{
+#ifdef USE_LIBXML
+	char		*s = PG_GETARG_CSTRING(0);
+	size_t		len;
+	xmltype		*vardata;
+
+	len = strlen(s);
+	vardata = palloc(len + VARHDRSZ);
+	VARATT_SIZEP(vardata) = len + VARHDRSZ;
+	memcpy(VARDATA(vardata), s, len);
+
+	/*
+	 * Parse the data to check if it is well-formed XML data.  Assume
+	 * that ERROR occurred if parsing failed.  Do we need DTD
+	 * validation (if DTD exists)?
+	 */
+	xml_parse(vardata, XML_PARSE_DTDATTR | XML_PARSE_DTDVALID, false);
+
+	PG_RETURN_XML_P(vardata);
+#else
+	NO_XML_SUPPORT();
+	return 0;
+#endif
+}
+
+
+Datum
+xml_out(PG_FUNCTION_ARGS)
+{
+	xmltype		*s = PG_GETARG_XML_P(0);
+	char		*result;
+	int32		len;
+	
+	len = VARSIZE(s) - VARHDRSZ;
+	result = palloc(len + 1);
+	memcpy(result, VARDATA(s), len);
+	result[len] = '\0';
+	
+	PG_RETURN_CSTRING(result);
+}
+
+
+#ifdef USE_LIBXML
+static void
+appendStringInfoText(StringInfo str, const text *t)
+{
+	appendBinaryStringInfo(str, VARDATA(t), VARSIZE(t) - VARHDRSZ);
+}
+
+
+static xmltype *
+stringinfo_to_xmltype(StringInfo buf)
+{
+	int32 len;
+	xmltype *result;
+
+	len = buf->len + VARHDRSZ;
+	result = palloc(len);
+	VARATT_SIZEP(result) = len;
+	memcpy(VARDATA(result), buf->data, buf->len);
+
+	return result;
+}
+#endif
+
+
+Datum
+xmlcomment(PG_FUNCTION_ARGS)
+{
+#ifdef USE_LIBXML
+	text *arg = PG_GETARG_TEXT_P(0);
+	int len =  VARATT_SIZEP(arg) - VARHDRSZ;
+	StringInfoData buf;
+	int i;
+
+	/* check for "--" in string or "-" at the end */
+	for (i = 1; i < len; i++)
+		if ((VARDATA(arg)[i] == '-' && VARDATA(arg)[i - 1] == '-')
+			|| (VARDATA(arg)[i] == '-' && i == len - 1))
+					ereport(ERROR,
+							(errcode(ERRCODE_INVALID_XML_COMMENT),
+							 errmsg("invalid XML comment")));
+
+	initStringInfo(&buf);
+	appendStringInfo(&buf, "<!--");
+	appendStringInfoText(&buf, arg);
+	appendStringInfo(&buf, "-->");
+
+	PG_RETURN_XML_P(stringinfo_to_xmltype(&buf));
+#else
+	NO_XML_SUPPORT();
+	return 0;
+#endif
+}
+
+
+Datum
+xmlparse(PG_FUNCTION_ARGS)
+{
+#ifdef USE_LIBXML
+	text	   *data;
+	bool		is_document;
+	bool		preserve_whitespace;
+
+	data = PG_GETARG_TEXT_P(0);
+
+	if (PG_NARGS() >= 2)
+		is_document = PG_GETARG_BOOL(1);
+	else
+		is_document = false;
+
+	if (PG_NARGS() >= 3)
+		preserve_whitespace = PG_GETARG_BOOL(2);
+	else
+		/*
+		 * Since the XMLPARSE grammar makes STRIP WHITESPACE the
+		 * default, this argument should really default to false.  But
+		 * until we have actually implemented whitespace stripping,
+		 * this would be annoying.
+		 */
+		preserve_whitespace = true;
+
+	if (!preserve_whitespace)
+		ereport(WARNING,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("XMLPARSE with STRIP WHITESPACE is not implemented")));
+
+	/*
+	 * Note, that here we try to apply DTD defaults
+	 * (XML_PARSE_DTDATTR) according to SQL/XML:10.16.7.d: 'Default
+	 * valies defined by internal DTD are applied'.  As for external
+	 * DTDs, we try to support them too, (see SQL/XML:10.16.7.e)
+	 */
+	xml_parse(data, XML_PARSE_DTDATTR, is_document); /* assume that ERROR occurred if parsing failed */
+
+	PG_RETURN_XML_P(data);
+#else
+	NO_XML_SUPPORT();
+	return 0;
+#endif
+}
+
+
+Datum
+xmlpi(PG_FUNCTION_ARGS)
+{
+#ifdef USE_LIBXML
+	char	   *target = NameStr(*PG_GETARG_NAME(0));
+	StringInfoData buf;
+
+	if (strlen(target) >= 3
+		&& (target[0] == 'x' || target[0] == 'X')
+		&& (target[1] == 'm' || target[1] == 'M')
+		&& (target[2] == 'l' || target[2] == 'L'))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("invalid XML processing instruction"),
+				 errdetail("XML processing instruction target name cannot start with \"xml\".")));
+	}
+
+	initStringInfo(&buf);
+
+	appendStringInfo(&buf, "<?");
+	appendStringInfoString(&buf, map_sql_identifier_to_xml_name(target, false));
+	if (PG_NARGS() > 1)
+	{
+		text *arg = PG_GETARG_TEXT_P(1);
+		char *string;
+
+		string = DatumGetCString(DirectFunctionCall1(textout, PointerGetDatum(arg)));
+		if (strstr(string, "?>"))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_XML_PROCESSING_INSTRUCTION),
+				 errmsg("invalid XML processing instruction"),
+				 errdetail("XML processing instruction cannot contain \"?>\".")));
+
+		appendStringInfoString(&buf, " ");
+		appendStringInfoString(&buf, string);
+	}
+	appendStringInfoString(&buf, "?>");
+
+	PG_RETURN_XML_P(stringinfo_to_xmltype(&buf));
+#else
+	NO_XML_SUPPORT();
+	return 0;
+#endif
+}
+
+
+Datum
+xmlroot(PG_FUNCTION_ARGS)
+{
+#ifdef USE_LIBXML
+	xmltype	   *data;
+	text	   *version;
+	int			standalone;
+	StringInfoData buf;
+
+	if (PG_ARGISNULL(0))
+		PG_RETURN_NULL();
+	else
+		data = PG_GETARG_XML_P(0);
+
+	if (PG_ARGISNULL(1))
+		version = NULL;
+	else
+		version = PG_GETARG_TEXT_P(1);
+
+	if (PG_ARGISNULL(2))
+		standalone = 0;
+	else
+	{
+		bool tmp = PG_GETARG_BOOL(2);
+		standalone = (tmp ? 1 : -1);
+	}
+
+	/*
+	 * FIXME: This is probably supposed to be cleverer if there
+	 * already is an XML preamble.
+	 */
+	initStringInfo(&buf);
+
+	appendStringInfo(&buf,"<?xml");
+	if (version) {
+		appendStringInfo(&buf, " version=\"");
+		appendStringInfoText(&buf, version);
+		appendStringInfo(&buf, "\"");
+	}
+	if (standalone)
+		appendStringInfo(&buf, " standalone=\"%s\"", (standalone == 1 ? "yes" : "no"));
+	appendStringInfo(&buf, "?>");
+	appendStringInfoText(&buf, (text *) data);
+
+	PG_RETURN_XML_P(stringinfo_to_xmltype(&buf));
+#else
+	NO_XML_SUPPORT();
+	return 0;
+#endif
+}
+
+
+/*
+ * Validate document (given as string) against DTD (given as external link)
+ * TODO !!! use text instead of cstring for second arg
+ * TODO allow passing DTD as a string value (not only as an URI)
+ * TODO redesign (see comment with '!!!' below)
+ */
+Datum
+xmlvalidate(PG_FUNCTION_ARGS)
+{
+#ifdef USE_LIBXML
+	text				*data = PG_GETARG_TEXT_P(0);
+	text				*dtdOrUri = PG_GETARG_TEXT_P(1);
+	bool				result = FALSE;
+	xmlParserCtxtPtr	ctxt; /* the parser context */
+	xmlDocPtr 			doc; /* the resulting document tree */
+	xmlDtdPtr			dtd;
+
+	xml_init();
+
+	ctxt = xmlNewParserCtxt();
+	if (ctxt == NULL)
+		xml_ereport(ERROR, "could not allocate parser context", ctxt);
+	doc = xmlCtxtReadMemory(ctxt, (char *) VARDATA(data), 
+							VARSIZE(data) - VARHDRSZ, PG_XML_DEFAULT_URI, NULL, 0);
+	if (doc == NULL)
+		xml_ereport(ERROR, "could not parse XML data", ctxt);
+
+#if 0
+	uri = xmlCreateURI();
+	ereport(NOTICE, (errcode(0),errmsg(" dtd - %s", dtdOrUri)));
+	dtd = palloc(sizeof(xmlDtdPtr));
+	uri = xmlParseURI(dtdOrUri);
+	if (uri == NULL)
+		xml_ereport(ERROR, "not implemented yet... (TODO)", ctxt);
+	else
+#endif
+		dtd = xmlParseDTD(NULL, xml_text2xmlChar(dtdOrUri));
+
+	if (dtd == NULL)
+	{
+#if 0
+		xmlFreeDoc(doc);
+		xmlFreeParserCtxt(ctxt);
+#endif
+		xml_ereport(ERROR, "could not load DTD", ctxt);
+	}
+
+	if (xmlValidateDtd(xmlNewValidCtxt(), doc, dtd) == 1)
+		result = TRUE;
+	
+#if 0
+	xmlFreeURI(uri);
+	xmlFreeDtd(dtd);
+	xmlFreeDoc(doc);
+	xmlFreeParserCtxt(ctxt);
+	xmlCleanupParser();
+#endif
+	
+	if (!result)
+		xml_ereport(NOTICE, "validation against DTD failed", ctxt);
+
+	PG_RETURN_BOOL(result);
+#else /* not USE_LIBXML */
+	NO_XML_SUPPORT();
+	return 0;
+#endif /* not USE_LIBXML */
+}
+
+
+#ifdef USE_LIBXML
+
+/*
+ * Container for some init stuff (not good design!)
+ * TODO xmlChar is utf8-char, make proper tuning (initdb with enc!=utf8 and check)
+ */
+static void
+xml_init(void)
+{
+	/*
+	 * Currently, we have no pure UTF-8 support for internals -- check
+	 * if we can work.
+	 */
+	if (sizeof (char) != sizeof (xmlChar))
+		ereport(ERROR, 
+				(errmsg("cannot initialize XML library"),
+				 errdetail("libxml2 has incompatible char type: sizeof(char)=%u, sizeof(xmlChar)=%u.", 
+						   sizeof(char), sizeof(xmlChar))));
+	
+	xmlMemSetup(xml_pfree, xml_palloc, xml_repalloc, xml_pstrdup);
+	xmlInitParser();
+	LIBXML_TEST_VERSION;
+	/* do not flood PG's logfile with libxml error messages - reset error handler*/ 
+	xmlSetGenericErrorFunc(NULL, xml_errorHandler);
+	xml_errmsg = NULL;
+	xml_errbuf = palloc(XML_ERRBUF_SIZE);
+	memset(xml_errbuf, 0, XML_ERRBUF_SIZE);
+}
+
+
+/*
+ * Convert a C string to XML internal representation
+ * (same things as for TEXT, but with checking the data for well-formedness
+ * and, moreover, validation against DTD, if needed).
+ * NOTICE: We use TEXT type as internal storage type. In the future,
+ * we plan to create own storage type (maybe several types/strategies)
+ * TODO predefined DTDs / XSDs and validation
+ * TODO validation against XML Schema
+ * TODO maybe, libxml2's xmlreader is better? (do not construct DOM, yet do not use SAX - see xml_reader.c)
+ * TODO what about internal URI for docs? (see PG_XML_DEFAULT_URI below)
+ */
+static xmlDocPtr
+xml_parse(text *data, int opts, bool is_document)
+{
+	bool				validationFailed = FALSE;
+	xmlParserCtxtPtr 	ctxt; /* the parser context */
+	xmlDocPtr 			doc; /* the resulting document tree */
+	int					res_code;
+	int32				len;
+	xmlChar				*string;
+#ifdef XML_DEBUG_DTD_CONST
+	xmlDtdPtr			dtd; /* pointer to DTD */
+#endif
+
+	xml_init();
+	
+	len = VARSIZE(data) - VARHDRSZ; /* will be useful later */
+	string = xml_text2xmlChar(data);
+	
+	ctxt = xmlNewParserCtxt();
+	if (ctxt == NULL)
+		xml_ereport(ERROR, "could not allocate parser context", ctxt);
+	
+	/* first, we try to parse the string as it is XML doc, then, as XML chunk */
+	ereport(DEBUG3, (errmsg("string to parse: %s", string)));
+	if (len > 4 && CMP5(string, '<', '?', 'x', 'm', 'l'))
+	{
+		/* consider it as DOCUMENT */
+		doc = xmlCtxtReadMemory(ctxt, string, len, PG_XML_DEFAULT_URI, NULL, opts);
+		if (doc == NULL)
+		{
+			xml_ereport(ERROR, "could not parse XML data", ctxt);
+#if 0
+			xmlFreeParserCtxt(ctxt);
+			xmlCleanupParser();
+			ereport(ERROR, (errmsg("could not parse XML data")));
+#endif
+		}
+	}
+	else
+	{
+		/* attempt to parse the string as if it is an XML fragment */
+		ereport(DEBUG3, (errmsg("the string is not an XML doc, trying to parse as a CHUNK")));
+		doc = xmlNewDoc(NULL);
+		/* TODO resolve: xmlParseBalancedChunkMemory assumes that string is UTF8 encoded! */
+		res_code = xmlParseBalancedChunkMemory(doc, NULL, NULL, 0, string, NULL);
+		if (res_code != 0)
+		{
+			xmlFreeParserCtxt(ctxt);
+			xmlCleanupParser();
+			xml_ereport_by_code(ERROR, "could not parse XML data", res_code);
+		}
+	}
+
+#ifdef XML_DEBUG_DTD_CONST
+	dtd = xmlParseDTD(NULL, (xmlChar *) XML_DEBUG_DTD_CONST);
+	xml_ereport(DEBUG3, "solid path to DTD was defined for debugging purposes", ctxt);
+	if (dtd == NULL)
+	{
+		xml_ereport(ERROR, "could not parse DTD data", ctxt);
+	}
+	else
+#else
+	/* if dtd for our xml data is detected... */
+	if ((doc->intSubset != NULL) || (doc->extSubset != NULL))
+#endif
+	{
+		/* assume that inline DTD exists - validation should be performed */
+#ifdef XML_DEBUG_DTD_CONST
+		if (xmlValidateDtd(xmlNewValidCtxt(), doc, dtd) != 1)
+#else
+		if (ctxt->valid == 0)
+#endif
+		{
+			/* DTD exists, but validator reported 'validation failed' */
+			validationFailed = TRUE;
+		}
+	}
+	
+	if (validationFailed)
+		xml_ereport(WARNING, "validation against DTD failed", ctxt);
+	
+	/* TODO encoding issues 
+	 * (thoughts:
+	 * 		CASE:
+	 *   		- XML data has explicit encoding attribute in its prolog
+	 *   		- if not, assume that enc. of XML data is the same as client's one
+	 * 
+	 * 		The common rule is to accept the XML data only if its encoding
+	 * 		is the same as encoding of the storage (server's). The other possible
+	 * 		option is to accept all the docs, but DO TRANSFORMATION and, if needed,
+	 * 		change the prolog.
+	 * 
+	 * 		I think I'd stick the first way (for the 1st version), 
+	 * 		it's much simplier (less errors...)
+	 * ) */
+	/* ... */
+	
+	xmlFreeParserCtxt(ctxt);
+	xmlCleanupParser();
+	
+	ereport(DEBUG3, (errmsg("XML data successfully parsed, encoding: %s", 
+		(char *) doc->encoding)));
+	
+	return doc;
+}
+
+
+/* 
+ * xmlChar<->text convertions 
+ */
+static xmlChar *
+xml_text2xmlChar(text *in)
+{
+	int32 		len = VARSIZE(in) - VARHDRSZ;
+	xmlChar		*res;
+
+	res = palloc(len + 1);
+	memcpy(res, VARDATA(in), len);
+	res[len] = '\0';
+	
+	return(res);
+}
+
+
+/* 
+ * Wrappers for memory management functions 
+ */
+static void *
+xml_palloc(size_t size)
+{
+	return palloc(size);
+}
+
+
+static void *
+xml_repalloc(void *ptr, size_t size)
+{
+	return repalloc(ptr, size);
+}
+
+
+static void
+xml_pfree(void *ptr)
+{
+	pfree(ptr);
+}
+
+
+static char *
+xml_pstrdup(const char *string)
+{
+	return pstrdup(string);
+}
+
+
+/*
+ * Wrapper for "ereport" function. 
+ * Adds detail - libxml's native error message, if any.
+ */
+static void
+xml_ereport(int level, char *msg, void *ctxt)
+{
+	char *xmlErrDetail;
+	int xmlErrLen, i;
+	xmlErrorPtr libxmlErr = NULL;
+	
+	if (xml_errmsg != NULL)
+	{
+		ereport(DEBUG1, (errmsg("%s", xml_errmsg)));
+		pfree(xml_errmsg);
+	}
+	
+	if (ctxt != NULL)
+		libxmlErr = xmlCtxtGetLastError(ctxt);
+	
+	if (libxmlErr == NULL)
+	{
+		if (level == ERROR)
+		{
+			xmlFreeParserCtxt(ctxt);
+			xmlCleanupParser();
+		}
+		ereport(level, (errmsg(msg)));
+	}
+	else
+	{
+		/* as usual, libxml error message contains '\n'; get rid of it */
+		xmlErrLen = strlen(libxmlErr->message); /* - 1; */
+		xmlErrDetail = (char *) palloc(xmlErrLen);
+		for (i = 0; i < xmlErrLen; i++)
+		{
+			if (libxmlErr->message[i] == '\n')
+				xmlErrDetail[i] = '.';
+			else
+				xmlErrDetail[i] = libxmlErr->message[i];
+		}
+		if (level == ERROR)
+		{
+			xmlFreeParserCtxt(ctxt);
+			xmlCleanupParser();
+		}
+		ereport(level, (errmsg(msg), errdetail("%s", xmlErrDetail)));
+	}
+}
+
+
+/*
+ * Error handler for libxml error messages
+ */
+static void
+xml_errorHandler(void *ctxt, const char *msg,...)
+{
+	va_list		args;
+	
+	va_start(args, msg);
+	vsnprintf(xml_errbuf, XML_ERRBUF_SIZE, msg, args);
+	va_end(args);
+	/* Now copy the argument across */
+	if (xml_errmsg == NULL)
+		xml_errmsg = pstrdup(xml_errbuf);
+	else
+	{
+		int32		xsize = strlen(xml_errmsg);
+
+		xml_errmsg = repalloc(xml_errmsg, (size_t) (xsize + strlen(xml_errbuf) + 1));
+		strncpy(&xml_errmsg[xsize - 1], xml_errbuf, strlen(xml_errbuf));
+		xml_errmsg[xsize + strlen(xml_errbuf) - 1] = '\0';
+	}
+	memset(xml_errbuf, 0, XML_ERRBUF_SIZE);
+}
+
+
+/*
+ * Return error message by libxml error code
+ * TODO make them closer to recommendations from Postgres manual
+ */
+static void
+xml_ereport_by_code(int level, char *msg, int code)
+{
+    const char *det;
+
+	if (code < 0)
+	{
+		ereport(level, (errmsg(msg)));
+		return;
+	}
+
+    switch (code) {
+        case XML_ERR_INTERNAL_ERROR:
+            det = "libxml internal error";
+            break;
+        case XML_ERR_ENTITY_LOOP:
+            det = "Detected an entity reference loop";
+            break;
+        case XML_ERR_ENTITY_NOT_STARTED:
+            det = "EntityValue: \" or ' expected";
+            break;
+        case XML_ERR_ENTITY_NOT_FINISHED:
+            det = "EntityValue: \" or ' expected";
+            break;
+        case XML_ERR_ATTRIBUTE_NOT_STARTED:
+            det = "AttValue: \" or ' expected";
+            break;
+        case XML_ERR_LT_IN_ATTRIBUTE:
+            det = "Unescaped '<' not allowed in attributes values";
+            break;
+        case XML_ERR_LITERAL_NOT_STARTED:
+            det = "SystemLiteral \" or ' expected";
+            break;
+        case XML_ERR_LITERAL_NOT_FINISHED:
+            det = "Unfinished System or Public ID \" or ' expected";
+            break;
+        case XML_ERR_MISPLACED_CDATA_END:
+            det = "Sequence ']]>' not allowed in content";
+            break;
+        case XML_ERR_URI_REQUIRED:
+            det = "SYSTEM or PUBLIC, the URI is missing";
+            break;
+        case XML_ERR_PUBID_REQUIRED:
+            det = "PUBLIC, the Public Identifier is missing";
+            break;
+        case XML_ERR_HYPHEN_IN_COMMENT:
+            det = "Comment must not contain '--' (double-hyphen)";
+            break;
+        case XML_ERR_PI_NOT_STARTED:
+            det = "xmlParsePI : no target name";
+            break;
+        case XML_ERR_RESERVED_XML_NAME:
+            det = "Invalid PI name";
+            break;
+        case XML_ERR_NOTATION_NOT_STARTED:
+            det = "NOTATION: Name expected here";
+            break;
+        case XML_ERR_NOTATION_NOT_FINISHED:
+            det = "'>' required to close NOTATION declaration";
+            break;
+        case XML_ERR_VALUE_REQUIRED:
+            det = "Entity value required";
+            break;
+        case XML_ERR_URI_FRAGMENT:
+            det = "Fragment not allowed";
+            break;
+        case XML_ERR_ATTLIST_NOT_STARTED:
+            det = "'(' required to start ATTLIST enumeration";
+            break;
+        case XML_ERR_NMTOKEN_REQUIRED:
+            det = "NmToken expected in ATTLIST enumeration";
+            break;
+        case XML_ERR_ATTLIST_NOT_FINISHED:
+            det = "')' required to finish ATTLIST enumeration";
+            break;
+        case XML_ERR_MIXED_NOT_STARTED:
+            det = "MixedContentDecl : '|' or ')*' expected";
+            break;
+        case XML_ERR_PCDATA_REQUIRED:
+            det = "MixedContentDecl : '#PCDATA' expected";
+            break;
+        case XML_ERR_ELEMCONTENT_NOT_STARTED:
+            det = "ContentDecl : Name or '(' expected";
+            break;
+        case XML_ERR_ELEMCONTENT_NOT_FINISHED:
+            det = "ContentDecl : ',' '|' or ')' expected";
+            break;
+        case XML_ERR_PEREF_IN_INT_SUBSET:
+            det = "PEReference: forbidden within markup decl in internal subset";
+            break;
+        case XML_ERR_GT_REQUIRED:
+            det = "Expected '>'";
+            break;
+        case XML_ERR_CONDSEC_INVALID:
+            det = "XML conditional section '[' expected";
+            break;
+        case XML_ERR_EXT_SUBSET_NOT_FINISHED:
+            det = "Content error in the external subset";
+            break;
+        case XML_ERR_CONDSEC_INVALID_KEYWORD:
+            det = "conditional section INCLUDE or IGNORE keyword expected";
+            break;
+        case XML_ERR_CONDSEC_NOT_FINISHED:
+            det = "XML conditional section not closed";
+            break;
+        case XML_ERR_XMLDECL_NOT_STARTED:
+            det = "Text declaration '<?xml' required";
+            break;
+        case XML_ERR_XMLDECL_NOT_FINISHED:
+            det = "parsing XML declaration: '?>' expected";
+            break;
+        case XML_ERR_EXT_ENTITY_STANDALONE:
+            det = "external parsed entities cannot be standalone";
+            break;
+        case XML_ERR_ENTITYREF_SEMICOL_MISSING:
+            det = "EntityRef: expecting ';'";
+            break;
+        case XML_ERR_DOCTYPE_NOT_FINISHED:
+            det = "DOCTYPE improperly terminated";
+            break;
+        case XML_ERR_LTSLASH_REQUIRED:
+            det = "EndTag: '</' not found";
+            break;
+        case XML_ERR_EQUAL_REQUIRED:
+            det = "Expected '='";
+            break;
+        case XML_ERR_STRING_NOT_CLOSED:
+            det = "String not closed expecting \" or '";
+            break;
+        case XML_ERR_STRING_NOT_STARTED:
+            det = "String not started expecting ' or \"";
+            break;
+        case XML_ERR_ENCODING_NAME:
+            det = "Invalid XML encoding name";
+            break;
+        case XML_ERR_STANDALONE_VALUE:
+            det = "Standalone accepts only 'yes' or 'no'";
+            break;
+        case XML_ERR_DOCUMENT_EMPTY:
+            det = "Document is empty";
+            break;
+        case XML_ERR_DOCUMENT_END:
+            det = "Extra content at the end of the document";
+            break;
+        case XML_ERR_NOT_WELL_BALANCED:
+            det = "Chunk is not well balanced";
+            break;
+        case XML_ERR_EXTRA_CONTENT:
+            det = "Extra content at the end of well balanced chunk";
+            break;
+        case XML_ERR_VERSION_MISSING:
+            det = "Malformed declaration expecting version";
+            break;
+        /* more err codes... Please, keep the order! */
+        case XML_ERR_ATTRIBUTE_WITHOUT_VALUE: /* 41 */
+        	det ="Attribute without value";
+        	break;
+        case XML_ERR_ATTRIBUTE_REDEFINED:
+        	det ="Attribute defined more than once in the same element";
+        	break;
+        case XML_ERR_COMMENT_NOT_FINISHED: /* 45 */
+            det = "Comment is not finished";
+            break;
+        case XML_ERR_NAME_REQUIRED: /* 68 */
+            det = "Element name not found";
+            break;
+        case XML_ERR_TAG_NOT_FINISHED: /* 77 */
+            det = "Closing tag not found";
+            break;
+        default:
+            det = "Unregistered error (libxml error code: %d)";
+            ereport(DEBUG1, (errmsg("Check out \"libxml/xmlerror.h\" and bring errcode \"%d\" processing to \"xml.c\".", code)));
+    }
+    
+	if (xml_errmsg != NULL)
+	{
+		ereport(DEBUG1, (errmsg("%s", xml_errmsg)));
+		pfree(xml_errmsg);
+	}
+    
+	ereport(level, (errmsg(msg), errdetail(det, code)));
+}
+
+
+/*
+ * Convert one char in the current server encoding to a Unicode
+ * codepoint.
+ */
+static pg_wchar
+sqlchar_to_unicode(unsigned char *s)
+{
+	int save_enc;
+	pg_wchar ret;
+	char *utf8string = pg_do_encoding_conversion(s, pg_mblen(s), GetDatabaseEncoding(), PG_UTF8);
+
+	save_enc = GetDatabaseEncoding();
+	SetDatabaseEncoding(PG_UTF8);
+	pg_mb2wchar_with_len(utf8string, &ret, pg_mblen(s));
+	SetDatabaseEncoding(save_enc);
+
+	return ret;
+}
+
+
+static bool
+is_valid_xml_namefirst(pg_wchar c)
+{
+	/* (Letter | '_' | ':') */
+	return (xmlIsBaseCharQ(c) || xmlIsIdeographicQ(c)
+			|| c == '_' || c == ':');
+}
+
+
+static bool
+is_valid_xml_namechar(pg_wchar c)
+{
+	/* Letter | Digit | '.' | '-' | '_' | ':' | CombiningChar | Extender */
+	return (xmlIsBaseCharQ(c) || xmlIsIdeographicQ(c)
+			|| xmlIsDigitQ(c)
+			|| c == '.' || c == '-' || c == '_' || c == ':'
+			|| xmlIsCombiningQ(c)
+			|| xmlIsExtenderQ(c));
+}
+#endif /* USE_LIBXML */
+
+
+/*
+ * Map SQL identifier to XML name; see SQL/XML:2003 section 9.1.
+ */
+char *
+map_sql_identifier_to_xml_name(unsigned char *ident, bool fully_escaped)
+{
+#ifdef USE_LIBXML
+	StringInfoData buf;
+	unsigned char *p;
+
+	initStringInfo(&buf);
+
+	for (p = ident; *p; p += pg_mblen(p))
+	{
+		if (*p == ':' && (p == ident || fully_escaped))
+			appendStringInfo(&buf, "_x003A_");
+		else if (*p == '_' && *(p+1) == 'x')
+			appendStringInfo(&buf, "_x005F_");
+		else if (fully_escaped && p == ident
+				 && ( *p == 'x' || *p == 'X')
+				 && ( *(p+1) == 'm' || *(p+1) == 'M')
+				 && ( *(p+2) == 'l' || *(p+2) == 'L'))
+		{
+			if (*p == 'x')
+				appendStringInfo(&buf, "_x0078_");
+			else
+				appendStringInfo(&buf, "_x0058_");
+		}
+		else
+		{
+			pg_wchar u = sqlchar_to_unicode(p);
+
+			if (!is_valid_xml_namechar(u)
+				|| (p == ident && !is_valid_xml_namefirst(u)))
+			appendStringInfo(&buf, "_x%04X_", (unsigned int) u);
+			else
+				appendBinaryStringInfo(&buf, p, pg_mblen(p));
+		}
+	}
+
+	return buf.data;
+#else /* not USE_LIBXML */
+	NO_XML_SUPPORT();
+	return NULL;
+#endif /* not USE_LIBXML */
+}
diff --git a/src/backend/utils/mb/mbutils.c b/src/backend/utils/mb/mbutils.c
index e91c8a2a58c..89845b08c16 100644
--- a/src/backend/utils/mb/mbutils.c
+++ b/src/backend/utils/mb/mbutils.c
@@ -4,7 +4,7 @@
  * (currently mule internal code (mic) is used)
  * Tatsuo Ishii
  *
- * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.59 2006/10/04 00:30:02 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.60 2006/12/21 16:05:15 petere Exp $
  */
 #include "postgres.h"
 
@@ -599,7 +599,7 @@ void
 SetDatabaseEncoding(int encoding)
 {
 	if (!PG_VALID_BE_ENCODING(encoding))
-		elog(ERROR, "invalid database encoding");
+		elog(ERROR, "invalid database encoding: %d", encoding);
 
 	DatabaseEncoding = &pg_enc2name_tbl[encoding];
 	Assert(DatabaseEncoding->encoding == encoding);