encoding_for_xmlCtxtReadMemory.patch

diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index c47624eff6..b09ce23cdb 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -3911,7 +3911,9 @@ xpath_internal(text *xpath_expr_text, xmltype *data, ArrayType *namespaces,
 		if (ctxt == NULL || xmlerrcxt->err_occurred)
 			xml_ereport(xmlerrcxt, ERROR, ERRCODE_OUT_OF_MEMORY,
 						"could not allocate parser context");
-		doc = xmlCtxtReadMemory(ctxt, (char *) string, len, NULL, NULL, 0);
+		doc = xmlCtxtReadMemory(ctxt, (char *) string, len, NULL,
+								pg_encoding_to_char(GetDatabaseEncoding()), 0);
+
 		if (doc == NULL || xmlerrcxt->err_occurred)
 			xml_ereport(xmlerrcxt, ERROR, ERRCODE_INVALID_XML_DOCUMENT,
 						"could not parse XML document");
@@ -4242,18 +4244,14 @@ XmlTableSetDocument(TableFuncScanState *state, Datum value)
 
 	xtCxt = GetXmlTableBuilderPrivateData(state, "XmlTableSetDocument");
 
-	/*
-	 * Use out function for casting to string (remove encoding property). See
-	 * comment in xml_out.
-	 */
-	str = xml_out_internal(xmlval, 0);
-
-	length = strlen(str);
+	str = VARDATA(xmlval);
+	length = VARSIZE(xmlval) - VARHDRSZ;
 	xstr = pg_xmlCharStrndup(str, length);
 
 	PG_TRY();
 	{
-		doc = xmlCtxtReadMemory(xtCxt->ctxt, (char *) xstr, length, NULL, NULL, 0);
+		doc = xmlCtxtReadMemory(xtCxt->ctxt, (char *) xstr, length, NULL,
+								pg_encoding_to_char(GetDatabaseEncoding()), 0);
 		if (doc == NULL || xtCxt->xmlerrcxt->err_occurred)
 			xml_ereport(xtCxt->xmlerrcxt, ERROR, ERRCODE_INVALID_XML_DOCUMENT,
 						"could not parse XML document");
diff --git a/src/test/regress/expected/xml.out b/src/test/regress/expected/xml.out
index bcc585d427..6a43896d40 100644
--- a/src/test/regress/expected/xml.out
+++ b/src/test/regress/expected/xml.out
@@ -1452,3 +1452,24 @@ SELECT xmltable.* FROM xmltest2, LATERAL xmltable(('/d/r/' || lower(_path) || 'c
  14
 (4 rows)
 
+-- XML is saved in database encoding with original encoding declaration.
+-- There can be incosistency based on wrong user input, different server/client
+-- encoding or reading XML with recv function. All XML functions should to
+-- work with this partially broken XML.
+DO $$
+DECLARE str text;
+BEGIN
+  -- leave early without error, when we are not sure about result of conversion
+  IF current_setting('server_encoding') NOT IN ('UTF8', 'LATIN2') THEN return; END IF;
+
+  -- build valid UTF8 XML with broken encoding declaration
+  str = '<?xml version="1.0" encoding="windows-1250"?><enprimeur><vino><id>909</id><remark>'
+          || convert_from('\xf2', 'windows-1250')
+          || '</remark></vino></enprimeur>';
+
+  -- should to work
+  RAISE NOTICE '%', xpath('/enprimeur/vino/id', str::xml);
+  RAISE NOTICE '%', (SELECT id FROM xmltable('/enprimeur/vino' PASSING (str::xml) COLUMNS id int));
+END; $$;
+NOTICE:  {<id>909</id>}
+NOTICE:  909
diff --git a/src/test/regress/sql/xml.sql b/src/test/regress/sql/xml.sql
index eb4687fb09..97a3aa9de2 100644
--- a/src/test/regress/sql/xml.sql
+++ b/src/test/regress/sql/xml.sql
@@ -558,3 +558,23 @@ INSERT INTO xmltest2 VALUES('<d><r><dc>2</dc></r></d>', 'D');
 SELECT xmltable.* FROM xmltest2, LATERAL xmltable('/d/r' PASSING x COLUMNS a int PATH '' || lower(_path) || 'c');
 SELECT xmltable.* FROM xmltest2, LATERAL xmltable(('/d/r/' || lower(_path) || 'c') PASSING x COLUMNS a int PATH '.');
 SELECT xmltable.* FROM xmltest2, LATERAL xmltable(('/d/r/' || lower(_path) || 'c') PASSING x COLUMNS a int PATH 'x' DEFAULT ascii(_path) - 54);
+
+-- XML is saved in database encoding with original encoding declaration.
+-- There can be incosistency based on wrong user input, different server/client
+-- encoding or reading XML with recv function. All XML functions should to
+-- work with this partially broken XML.
+DO $$
+DECLARE str text;
+BEGIN
+  -- leave early without error, when we are not sure about result of conversion
+  IF current_setting('server_encoding') NOT IN ('UTF8', 'LATIN2') THEN return; END IF;
+
+  -- build valid UTF8 XML with broken encoding declaration
+  str = '<?xml version="1.0" encoding="windows-1250"?><enprimeur><vino><id>909</id><remark>'
+          || convert_from('\xf2', 'windows-1250')
+          || '</remark></vino></enprimeur>';
+
+  -- should to work
+  RAISE NOTICE '%', xpath('/enprimeur/vino/id', str::xml);
+  RAISE NOTICE '%', (SELECT id FROM xmltable('/enprimeur/vino' PASSING (str::xml) COLUMNS id int));
+END; $$;