XML Support: Specifications and Development

XML Support Speciﬁcations and Development Peter Eisentraut PostgreSQL Anniversary Summit July 8–9, 2006 Toronto Peter Eisentraut XML Support

XML Support Types of “XML Support”: XML data type and support functions XML export format Mapping XML documents to SQL databases Peter Eisentraut XML Support

Speciﬁcations ISO/IEC 9075-14:2003 (“XML-Related Speciﬁcations” – SQL/XML) ISO/IEC 9075-14:2006, as of 2006-06-12 Already implemented by IBM DB/2, Microsoft SQL Server, OpenLink Virtuoso, Oracle, . . . More information: http://www.sqlx.org/ Peter Eisentraut XML Support

XML Data Type CREATE TABLE test ( ..., data xml, ... ); Features: Input checking Support functions Peter Eisentraut XML Support

XML Input/Output No string literals as input XMLPARSE ( DOCUMENT|CONTENT value ) --> xml XMLSERIALIZE ( DOCUMENT|CONTENT xmlvalue AS varchar ) --> varchar These could serve as PostgreSQL input/output functions. Peter Eisentraut XML Support

XML Support Functions XMLCOMMENT XMLCONCAT XMLELEMENT XMLFOREST XMLPI XMLROOT XMLAGG IS DOCUMENT, IS NOT DOCUMENT Peter Eisentraut XML Support

XMLELEMENT Example XMLROOT ( <?xml version=’1.0’ XMLELEMENT ( standalone=’yes’ ?> NAME ’gazonk’, <gazonk name=’val’ XMLATTRIBUTES ( num=’2’> ’val’ AS ’name’, <qux>foo</qux> 1 + 1 AS ’num’ </gazonk> ), XMLELEMENT ( NAME ’qux’, ’foo’ ) ), VERSION ’1.0’, STANDALONE YES ) Peter Eisentraut XML Support

XMLFOREST Example SELECT xmlforest ( "FirstName" as "FName", "LastName" as "LName", ’string’ as "str", "Title", "Region" ) FROM "Demo"."demo"."Employees"; might result in <FName>Nancy</FName> <LName>Davolio</LName> <str>string</str> <Title>Sales Representative</Title> <Region>WA</Region> . . . <FName>Anne</FName> <LName>Dodsworth</LName> <str>string</str> <Title>Sales Representative</Title> (1 row per record) Peter Eisentraut XML Support

XMLAGG Example SELECT xmlelement (’Emp’, xmlattributes (’Sales Representative’ as "Title"), xmlagg (xmlelement (’Name’, "FirstName", ’ ’, "LastName"))) FROM "Demo"."demo"."Employees" WHERE "Title" = ’Sales Representative’; might result in <Emp Title="Sales Representative"> <Name>Nancy Davolio</Name> <Name>Janet Leverling</Name> <Name>Margaret Peacock</Name> <Name>Michael Suyama</Name> <Name>Robert King</Name> <Name>Anne Dodsworth</Name> </Emp> (1 row) Peter Eisentraut XML Support

SQL:2006 More speciﬁc XML data type: XML XML(DOCUMENT) XML(CONTENT) XML(SEQUENCE) XML(DOCUMENT(ANY)) XML(DOCUMENT(UNTYPED)) XML(DOCUMENT(XMLSCHEMA ’http://...’)) More functions: XMLDOCUMENT XMLTEXT XMLVALIDATE IS CONTENT IS VALID More options everywhere XQuery Peter Eisentraut XML Support

XML Data Type Status Current status: Google Summer of Code project works on SQL:2003 (Nikolay Samokhvalov) Previous patches for support functions available, but work with text data type (Pavel Stehule) Also: Integrate contrib/xml functionality Peter Eisentraut XML Support

Implementation Issues Uses libxml (LGPL) Encoding handling Memory management Optional/mandatory? Peter Eisentraut XML Support

For the Future XQuery support (SQL:2006) Ctree indexes Peter Eisentraut XML Support

XML Export Format Map SQL schema to XML Schema Map database contents to XML document Useful for: Postprocessing using XSLT pg_dump psql? Peter Eisentraut XML Support

Mapping Names SQL <identiﬁer> fully-escaped XML name partially-escaped XML name employee EMPLOYEE EMPLOYEE "employee" employee employee "hire date" hire_x0020_date hire_x0020_date "comp_plan" comp_x005F_plan comp_x005F_plan "dept:id" dept_x003A_id dept:id xmlcol _xFFFF_xmlcol xmlcol Peter Eisentraut XML Support

XML Schema Mapping Example CREATE TABLE test (a int PRIMARY KEY, b varchar(200)); is mapped to <xsd:complexType name="RowType.catalog.schema.test"> <xsd:sequence> <xsd:element name="a" type="INTEGER"></xsd:element> <xsd:element name="b" type="VARCHAR_200_200" minOccurs="0"></xsd:element> </xsd:sequence> </xsd:complexType> <xsd:complexType name="TableType.catalog.schema.test"> <xsd:sequence> <xsd:element name="row" type="RowType.catalog.schema.test" minOccurs="0" maxOccurs="unbounded" /> </xsd:sequence> </xsd:complexType> Peter Eisentraut XML Support

XML Export Format Example <catalogname> <schemaname> <tablename> <row> <colname1>value</colname1> <colname2 xsi:nil=’true’/> ... </row> ... </tablename> ... </schemaname> ... </catalogname> Peter Eisentraut XML Support

XML Export Format Status Prototype available Would like XML data type ﬁrst Where to put it? pg_dump? psql? user-deﬁned functions? Peter Eisentraut XML Support

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XML Support: Specifications and Development

by Peter Eisentraut on Jun 19, 2009

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