Fix XMLTABLE() deparsing to quote namespace names if necessary.

When deparsing an XMLTABLE() expression, XML namespace names were not
quoted. However, since they are parsed as ColLabel tokens, some names
require double quotes to ensure that they are properly interpreted.
Fix by using quote_identifier() in the deparsing code.

Back-patch to all supported versions.

Dean Rasheed, reviewed by Tom Lane.

Discussion: https://postgr.es/m/CAEZATCXTpAS%3DncfLNTZ7YS6O5puHeLg_SUYAit%2Bcs7wsrd9Msg%40mail.gmail.com

src/backend/utils/adt/ruleutils.c

@@ -11814,7 +11814,8 @@ get_xmltable(TableFunc *tf, deparse_context *context, bool showimplicit)
 			if (ns_node != NULL)
 			{
 				get_rule_expr(expr, context, showimplicit);
-				appendStringInfo(buf, " AS %s", strVal(ns_node));
+				appendStringInfo(buf, " AS %s",
+								 quote_identifier(strVal(ns_node)));
 			}
 			else
 			{

src/test/regress/expected/xml.out

@@ -1379,16 +1379,20 @@ SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
  10
 (1 row)
 
-CREATE VIEW xmltableview2 AS SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
-                      '/zz:rows/zz:row'
+CREATE VIEW xmltableview2 AS SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS "Zz"),
+                      '/Zz:rows/Zz:row'
                       PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'
-                      COLUMNS a int PATH 'zz:a');
+                      COLUMNS a int PATH 'Zz:a');
 SELECT * FROM xmltableview2;
  a  
 ----
  10
 (1 row)
 
+\sv xmltableview2
+CREATE OR REPLACE VIEW public.xmltableview2 AS
+ SELECT a
+   FROM XMLTABLE(XMLNAMESPACES ('http://x.y'::text AS "Zz"), ('/Zz:rows/Zz:row'::text) PASSING ('<rows xmlns="http://x.y"><row><a>10</a></row></rows>'::xml) COLUMNS a integer PATH ('Zz:a'::text))
 SELECT * FROM XMLTABLE(XMLNAMESPACES(DEFAULT 'http://x.y'),
                       '/rows/row'
                       PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'

src/test/regress/expected/xml_1.out

@@ -1046,10 +1046,10 @@ ERROR:  unsupported XML feature
 LINE 3:                       PASSING '<rows xmlns="http://x.y"><row...
                                       ^
 DETAIL:  This functionality requires the server to be built with libxml support.
-CREATE VIEW xmltableview2 AS SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
-                      '/zz:rows/zz:row'
+CREATE VIEW xmltableview2 AS SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS "Zz"),
+                      '/Zz:rows/Zz:row'
                       PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'
-                      COLUMNS a int PATH 'zz:a');
+                      COLUMNS a int PATH 'Zz:a');
 ERROR:  unsupported XML feature
 LINE 3:                       PASSING '<rows xmlns="http://x.y"><row...
                                       ^
@@ -1058,6 +1058,8 @@ SELECT * FROM xmltableview2;
 ERROR:  relation "xmltableview2" does not exist
 LINE 1: SELECT * FROM xmltableview2;
                       ^
+\sv xmltableview2
+ERROR:  relation "xmltableview2" does not exist
 SELECT * FROM XMLTABLE(XMLNAMESPACES(DEFAULT 'http://x.y'),
                       '/rows/row'
                       PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'

src/test/regress/expected/xml_2.out

@@ -1365,16 +1365,20 @@ SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
  10
 (1 row)
 
-CREATE VIEW xmltableview2 AS SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
-                      '/zz:rows/zz:row'
+CREATE VIEW xmltableview2 AS SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS "Zz"),
+                      '/Zz:rows/Zz:row'
                       PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'
-                      COLUMNS a int PATH 'zz:a');
+                      COLUMNS a int PATH 'Zz:a');
 SELECT * FROM xmltableview2;
  a  
 ----
  10
 (1 row)
 
+\sv xmltableview2
+CREATE OR REPLACE VIEW public.xmltableview2 AS
+ SELECT a
+   FROM XMLTABLE(XMLNAMESPACES ('http://x.y'::text AS "Zz"), ('/Zz:rows/Zz:row'::text) PASSING ('<rows xmlns="http://x.y"><row><a>10</a></row></rows>'::xml) COLUMNS a integer PATH ('Zz:a'::text))
 SELECT * FROM XMLTABLE(XMLNAMESPACES(DEFAULT 'http://x.y'),
                       '/rows/row'
                       PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'

src/test/regress/sql/xml.sql

@@ -439,13 +439,15 @@ SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
                       PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'
                       COLUMNS a int PATH 'zz:a');
 
-CREATE VIEW xmltableview2 AS SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
-                      '/zz:rows/zz:row'
+CREATE VIEW xmltableview2 AS SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS "Zz"),
+                      '/Zz:rows/Zz:row'
                       PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'
-                      COLUMNS a int PATH 'zz:a');
+                      COLUMNS a int PATH 'Zz:a');
 
 SELECT * FROM xmltableview2;
 
+\sv xmltableview2
+
 SELECT * FROM XMLTABLE(XMLNAMESPACES(DEFAULT 'http://x.y'),
                       '/rows/row'
                       PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'