Subject: Re: PostgreSQL vs SQL/XML Standards
To: Pavel Stehule <pavel.stehule@gmail.com>,
 Markus Winand <markus.winand@winand.at>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>,
 Chapman Flack <chap@anastigmatix.net>, Tom Lane <tgl@sss.pgh.pa.us>,
 PostgreSQL Hackers <pgsql-hackers@postgresql.org>
References: 
 <CAFj8pRDFQJMoKf-X+3p1ASwU02nnXfAXrg83Z3fHUBd-Gwuuxw@mail.gmail.com>
 <20181025194720.ylmw64xqlnjr5wja@alvherre.pgsql>
 <CAFj8pRB10LxRcYYKWb5omjtAQq_bEVWiQ9B6V=kRZYMvM0B-_w@mail.gmail.com>
 <CAFj8pRBr5tY5b=8gKptwOyuPf8f3fvyHbXNbSCU03guNh-johw@mail.gmail.com>
 <CAFj8pRA6J25CtAZ2TuRvxK3gat7-bBUYh0rfE2yM7Hj9GD14Dg@mail.gmail.com>
 <FB592C2F-E2F3-42FD-A342-EE41BECD3771@winand.at>
 <CAFj8pRC_bi4uzE3Z-XXuGnLFPP-7cZ-zr2JhGauWm3E8K2MqEg@mail.gmail.com>
From: Arthur Zakirov <a.zakirov@postgrespro.ru>
Message-ID: <89664994-34c5-089b-dd28-68be2beb73c3@postgrespro.ru>
Date: Thu, 10 Jan 2019 16:00:18 +0300
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Hello Pavel,

On 09.11.2018 07:07, Pavel Stehule wrote:
> I used your patch and append regress tests. I checked the result against 
> Oracle.

I checked the patch with Chap cases. The patch fixes handling of 
boolean, number types which mentioned in the wiki.

I have a few comments related to the code and the documentation. I 
attached the patch, which fixes it.

There is an example in the documentation:

SELECT xmltable.*
   FROM xmlelements, XMLTABLE('/root' PASSING data COLUMNS element text);
        element
----------------------
    Hello2a2   bbbCC

With the patch XMLTABLE returns different result now.

copy_and_safe_free_xmlchar() function should be hid by #ifdef 
USE_LIBXML, otherwise I get an error if I build the Postgres without 
--with-libxml.

There is a comment within XmlTableGetValue(). I changed it, mainly I 
used Markus patch from the related thread mentioned by Alvaro.

Please see the changes in the patch.

-- 
Arthur Zakirov
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company

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diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 90d67f1acf..06f3f69073 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -10999,9 +10999,9 @@ $$ AS data;
 
 SELECT xmltable.*
   FROM xmlelements, XMLTABLE('/root' PASSING data COLUMNS element text);
-       element        
-----------------------
-   Hello2a2   bbbCC  
+         element         
+-------------------------
+   Hello2a2   bbbxxxCC  
 ]]></screen>
     </para>
 
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index a83882f5de..df7f0cc20d 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -4427,6 +4427,7 @@ XmlTableFetchRow(TableFuncScanState *state)
 #endif							/* not USE_LIBXML */
 }
 
+#ifdef USE_LIBXML
 /*
  * Copy XmlChar string to PostgreSQL memory. Ensure releasing of
  * source xmllib string.
@@ -4455,6 +4456,7 @@ copy_and_safe_free_xmlchar(xmlChar *str)
 
 	return result;
 }
+#endif
 
 /*
  * XmlTableGetValue
@@ -4504,9 +4506,9 @@ XmlTableGetValue(TableFuncScanState *state, int colnum,
 		/*
 		 * There are four possible cases, depending on the number of nodes
 		 * returned by the XPath expression and the type of the target column:
-		 * a) XPath returns no nodes.  b) One node is returned, and column is
-		 * of type XML.  c) One node, column type other than XML.  d) Multiple
-		 * nodes are returned.
+		 * a) XPath returns no nodes.  b) The target type is XML (return all
+		 * as XML).  For non-XML types:  c) One node (return content).
+		 * d) Multiple nodes (error).
 		 */
 		if (xpathobj->type == XPATH_NODESET)
 		{

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