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Support XMLTABLE query expression
XMLTABLE is defined by the SQL/XML standard as a feature that allows turning XML-formatted data into relational form, so that it can be used as a <table primary> in the FROM clause of a query. This new construct provides significant simplicity and performance benefit for XML data processing; what in a client-side custom implementation was reported to take 20 minutes can be executed in 400ms using XMLTABLE. (The same functionality was said to take 10 seconds using nested PostgreSQL XPath function calls, and 5 seconds using XMLReader under PL/Python). The implemented syntax deviates slightly from what the standard requires. First, the standard indicates that the PASSING clause is optional and that multiple XML input documents may be given to it; we make it mandatory and accept a single document only. Second, we don't currently support a default namespace to be specified. This implementation relies on a new executor node based on a hardcoded method table. (Because the grammar is fixed, there is no extensibility in the current approach; further constructs can be implemented on top of this such as JSON_TABLE, but they require changes to core code.) Author: Pavel Stehule, Álvaro Herrera Extensively reviewed by: Craig Ringer Discussion: https://postgr.es/m/CAFj8pRAgfzMD-LoSmnMGybD0WsEznLHWap8DO79+-GTRAPR4qA@mail.gmail.com
This commit is contained in:
Alvaro Herrera
@@ -270,3 +270,291 @@ SELECT XMLPARSE(DOCUMENT '<!DOCTYPE foo [<!ENTITY c SYSTEM "/etc/passwd">]><foo>
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SELECT XMLPARSE(DOCUMENT '<!DOCTYPE foo [<!ENTITY c SYSTEM "/etc/no.such.file">]><foo>&c;</foo>');
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-- This might or might not load the requested DTD, but it mustn't throw error.
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SELECT XMLPARSE(DOCUMENT '<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"><chapter> </chapter>');
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-- XMLPATH tests
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CREATE TABLE xmldata(data xml);
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INSERT INTO xmldata VALUES('<ROWS>
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<ROW id="1">
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<COUNTRY_ID>AU</COUNTRY_ID>
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<COUNTRY_NAME>Australia</COUNTRY_NAME>
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<REGION_ID>3</REGION_ID>
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</ROW>
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<ROW id="2">
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<COUNTRY_ID>CN</COUNTRY_ID>
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<COUNTRY_NAME>China</COUNTRY_NAME>
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<REGION_ID>3</REGION_ID>
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</ROW>
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<ROW id="3">
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<COUNTRY_ID>HK</COUNTRY_ID>
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<COUNTRY_NAME>HongKong</COUNTRY_NAME>
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<REGION_ID>3</REGION_ID>
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</ROW>
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<ROW id="4">
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<COUNTRY_ID>IN</COUNTRY_ID>
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<COUNTRY_NAME>India</COUNTRY_NAME>
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<REGION_ID>3</REGION_ID>
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</ROW>
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<ROW id="5">
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<COUNTRY_ID>JP</COUNTRY_ID>
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<COUNTRY_NAME>Japan</COUNTRY_NAME>
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<REGION_ID>3</REGION_ID><PREMIER_NAME>Sinzo Abe</PREMIER_NAME>
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</ROW>
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<ROW id="6">
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<COUNTRY_ID>SG</COUNTRY_ID>
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<COUNTRY_NAME>Singapore</COUNTRY_NAME>
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<REGION_ID>3</REGION_ID><SIZE unit="km">791</SIZE>
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</ROW>
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</ROWS>');
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-- XMLTABLE with columns
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SELECT xmltable.*
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FROM (SELECT data FROM xmldata) x,
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LATERAL XMLTABLE('/ROWS/ROW'
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PASSING data
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COLUMNS id int PATH '@id',
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_id FOR ORDINALITY,
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country_name text PATH 'COUNTRY_NAME' NOT NULL,
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country_id text PATH 'COUNTRY_ID',
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region_id int PATH 'REGION_ID',
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size float PATH 'SIZE',
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unit text PATH 'SIZE/@unit',
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premier_name text PATH 'PREMIER_NAME' DEFAULT 'not specified');
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CREATE VIEW xmltableview1 AS SELECT xmltable.*
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FROM (SELECT data FROM xmldata) x,
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LATERAL XMLTABLE('/ROWS/ROW'
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PASSING data
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COLUMNS id int PATH '@id',
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_id FOR ORDINALITY,
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country_name text PATH 'COUNTRY_NAME' NOT NULL,
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country_id text PATH 'COUNTRY_ID',
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region_id int PATH 'REGION_ID',
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size float PATH 'SIZE',
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unit text PATH 'SIZE/@unit',
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premier_name text PATH 'PREMIER_NAME' DEFAULT 'not specified');
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SELECT * FROM xmltableview1;
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\sv xmltableview1
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EXPLAIN (COSTS OFF) SELECT * FROM xmltableview1;
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EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM xmltableview1;
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-- XMLNAMESPACES tests
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SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
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'/zz:rows/zz:row'
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PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'
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COLUMNS a int PATH 'zz:a');
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CREATE VIEW xmltableview2 AS SELECT * FROM XMLTABLE(XMLNAMESPACES('http://x.y' AS zz),
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'/zz:rows/zz:row'
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PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'
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COLUMNS a int PATH 'zz:a');
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SELECT * FROM xmltableview2;
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SELECT * FROM XMLTABLE(XMLNAMESPACES(DEFAULT 'http://x.y'),
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'/rows/row'
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PASSING '<rows xmlns="http://x.y"><row><a>10</a></row></rows>'
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COLUMNS a int PATH 'a');
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-- used in prepare statements
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PREPARE pp AS
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SELECT xmltable.*
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FROM (SELECT data FROM xmldata) x,
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LATERAL XMLTABLE('/ROWS/ROW'
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PASSING data
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COLUMNS id int PATH '@id',
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_id FOR ORDINALITY,
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country_name text PATH 'COUNTRY_NAME' NOT NULL,
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country_id text PATH 'COUNTRY_ID',
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region_id int PATH 'REGION_ID',
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size float PATH 'SIZE',
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unit text PATH 'SIZE/@unit',
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premier_name text PATH 'PREMIER_NAME' DEFAULT 'not specified');
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EXECUTE pp;
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SELECT xmltable.* FROM xmldata, LATERAL xmltable('/ROWS/ROW[COUNTRY_NAME="Japan" or COUNTRY_NAME="India"]' PASSING data COLUMNS "COUNTRY_NAME" text, "REGION_ID" int);
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SELECT xmltable.* FROM xmldata, LATERAL xmltable('/ROWS/ROW[COUNTRY_NAME="Japan" or COUNTRY_NAME="India"]' PASSING data COLUMNS id FOR ORDINALITY, "COUNTRY_NAME" text, "REGION_ID" int);
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SELECT xmltable.* FROM xmldata, LATERAL xmltable('/ROWS/ROW[COUNTRY_NAME="Japan" or COUNTRY_NAME="India"]' PASSING data COLUMNS id int PATH '@id', "COUNTRY_NAME" text, "REGION_ID" int);
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SELECT xmltable.* FROM xmldata, LATERAL xmltable('/ROWS/ROW[COUNTRY_NAME="Japan" or COUNTRY_NAME="India"]' PASSING data COLUMNS id int PATH '@id');
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SELECT xmltable.* FROM xmldata, LATERAL xmltable('/ROWS/ROW[COUNTRY_NAME="Japan" or COUNTRY_NAME="India"]' PASSING data COLUMNS id FOR ORDINALITY);
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SELECT xmltable.* FROM xmldata, LATERAL xmltable('/ROWS/ROW[COUNTRY_NAME="Japan" or COUNTRY_NAME="India"]' PASSING data COLUMNS id int PATH '@id', "COUNTRY_NAME" text, "REGION_ID" int, rawdata xml PATH '.');
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SELECT xmltable.* FROM xmldata, LATERAL xmltable('/ROWS/ROW[COUNTRY_NAME="Japan" or COUNTRY_NAME="India"]' PASSING data COLUMNS id int PATH '@id', "COUNTRY_NAME" text, "REGION_ID" int, rawdata xml PATH './*');
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SELECT * FROM xmltable('/root' passing '<root><element>a1a<!-- aaaa -->a2a<?aaaaa?> <!--z--> bbbb<x>xxx</x>cccc</element></root>' COLUMNS element text);
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SELECT * FROM xmltable('/root' passing '<root><element>a1a<!-- aaaa -->a2a<?aaaaa?> <!--z--> bbbb<x>xxx</x>cccc</element></root>' COLUMNS element text PATH 'element/text()'); -- should fail
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-- CDATA test
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select * from xmltable('r' passing '<d><r><c><![CDATA[<hello> &"<>!<a>foo</a>]]></c></r><r><c>2</c></r></d>' columns c text);
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-- XML builtin entities
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SELECT * FROM xmltable('/x/a' PASSING '<x><a><ent>'</ent></a><a><ent>"</ent></a><a><ent>&</ent></a><a><ent><</ent></a><a><ent>></ent></a></x>' COLUMNS ent text);
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SELECT * FROM xmltable('/x/a' PASSING '<x><a><ent>'</ent></a><a><ent>"</ent></a><a><ent>&</ent></a><a><ent><</ent></a><a><ent>></ent></a></x>' COLUMNS ent xml);
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EXPLAIN (VERBOSE, COSTS OFF)
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SELECT xmltable.*
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FROM (SELECT data FROM xmldata) x,
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LATERAL XMLTABLE('/ROWS/ROW'
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PASSING data
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COLUMNS id int PATH '@id',
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_id FOR ORDINALITY,
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country_name text PATH 'COUNTRY_NAME' NOT NULL,
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country_id text PATH 'COUNTRY_ID',
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region_id int PATH 'REGION_ID',
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size float PATH 'SIZE',
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unit text PATH 'SIZE/@unit',
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premier_name text PATH 'PREMIER_NAME' DEFAULT 'not specified');
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-- test qual
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SELECT xmltable.* FROM xmldata, LATERAL xmltable('/ROWS/ROW[COUNTRY_NAME="Japan" or COUNTRY_NAME="India"]' PASSING data COLUMNS "COUNTRY_NAME" text, "REGION_ID" int) WHERE "COUNTRY_NAME" = 'Japan';
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EXPLAIN (VERBOSE, COSTS OFF)
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SELECT xmltable.* FROM xmldata, LATERAL xmltable('/ROWS/ROW[COUNTRY_NAME="Japan" or COUNTRY_NAME="India"]' PASSING data COLUMNS "COUNTRY_NAME" text, "REGION_ID" int) WHERE "COUNTRY_NAME" = 'Japan';
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-- should to work with more data
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INSERT INTO xmldata VALUES('<ROWS>
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<ROW id="10">
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<COUNTRY_ID>CZ</COUNTRY_ID>
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<COUNTRY_NAME>Czech Republic</COUNTRY_NAME>
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<REGION_ID>2</REGION_ID><PREMIER_NAME>Milos Zeman</PREMIER_NAME>
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</ROW>
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<ROW id="11">
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<COUNTRY_ID>DE</COUNTRY_ID>
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<COUNTRY_NAME>Germany</COUNTRY_NAME>
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<REGION_ID>2</REGION_ID>
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</ROW>
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<ROW id="12">
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<COUNTRY_ID>FR</COUNTRY_ID>
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<COUNTRY_NAME>France</COUNTRY_NAME>
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<REGION_ID>2</REGION_ID>
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</ROW>
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</ROWS>');
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INSERT INTO xmldata VALUES('<ROWS>
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<ROW id="20">
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<COUNTRY_ID>EG</COUNTRY_ID>
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<COUNTRY_NAME>Egypt</COUNTRY_NAME>
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<REGION_ID>1</REGION_ID>
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</ROW>
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<ROW id="21">
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<COUNTRY_ID>SD</COUNTRY_ID>
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<COUNTRY_NAME>Sudan</COUNTRY_NAME>
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<REGION_ID>1</REGION_ID>
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</ROW>
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</ROWS>');
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SELECT xmltable.*
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FROM (SELECT data FROM xmldata) x,
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LATERAL XMLTABLE('/ROWS/ROW'
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PASSING data
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COLUMNS id int PATH '@id',
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_id FOR ORDINALITY,
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country_name text PATH 'COUNTRY_NAME' NOT NULL,
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country_id text PATH 'COUNTRY_ID',
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region_id int PATH 'REGION_ID',
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size float PATH 'SIZE',
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unit text PATH 'SIZE/@unit',
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premier_name text PATH 'PREMIER_NAME' DEFAULT 'not specified');
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SELECT xmltable.*
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FROM (SELECT data FROM xmldata) x,
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LATERAL XMLTABLE('/ROWS/ROW'
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PASSING data
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COLUMNS id int PATH '@id',
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_id FOR ORDINALITY,
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country_name text PATH 'COUNTRY_NAME' NOT NULL,
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country_id text PATH 'COUNTRY_ID',
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region_id int PATH 'REGION_ID',
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size float PATH 'SIZE',
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unit text PATH 'SIZE/@unit',
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premier_name text PATH 'PREMIER_NAME' DEFAULT 'not specified')
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WHERE region_id = 2;
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EXPLAIN (VERBOSE, COSTS OFF)
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SELECT xmltable.*
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FROM (SELECT data FROM xmldata) x,
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LATERAL XMLTABLE('/ROWS/ROW'
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PASSING data
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COLUMNS id int PATH '@id',
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_id FOR ORDINALITY,
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country_name text PATH 'COUNTRY_NAME' NOT NULL,
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country_id text PATH 'COUNTRY_ID',
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region_id int PATH 'REGION_ID',
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size float PATH 'SIZE',
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unit text PATH 'SIZE/@unit',
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premier_name text PATH 'PREMIER_NAME' DEFAULT 'not specified')
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WHERE region_id = 2;
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-- should fail, NULL value
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SELECT xmltable.*
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FROM (SELECT data FROM xmldata) x,
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LATERAL XMLTABLE('/ROWS/ROW'
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PASSING data
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COLUMNS id int PATH '@id',
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_id FOR ORDINALITY,
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country_name text PATH 'COUNTRY_NAME' NOT NULL,
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country_id text PATH 'COUNTRY_ID',
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region_id int PATH 'REGION_ID',
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size float PATH 'SIZE' NOT NULL,
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unit text PATH 'SIZE/@unit',
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premier_name text PATH 'PREMIER_NAME' DEFAULT 'not specified');
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-- if all is ok, then result is empty
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-- one line xml test
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WITH
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x AS (SELECT proname, proowner, procost::numeric, pronargs,
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array_to_string(proargnames,',') as proargnames,
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case when proargtypes <> '' then array_to_string(proargtypes::oid[],',') end as proargtypes
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FROM pg_proc WHERE proname = 'f_leak'),
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y AS (SELECT xmlelement(name proc,
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xmlforest(proname, proowner,
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procost, pronargs,
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proargnames, proargtypes)) as proc
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FROM x),
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z AS (SELECT xmltable.*
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FROM y,
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LATERAL xmltable('/proc' PASSING proc
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COLUMNS proname name,
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proowner oid,
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procost float,
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pronargs int,
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proargnames text,
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proargtypes text))
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SELECT * FROM z
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EXCEPT SELECT * FROM x;
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-- multi line xml test, result should be empty too
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WITH
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x AS (SELECT proname, proowner, procost::numeric, pronargs,
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array_to_string(proargnames,',') as proargnames,
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case when proargtypes <> '' then array_to_string(proargtypes::oid[],',') end as proargtypes
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FROM pg_proc),
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y AS (SELECT xmlelement(name data,
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xmlagg(xmlelement(name proc,
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xmlforest(proname, proowner, procost,
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pronargs, proargnames, proargtypes)))) as doc
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FROM x),
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z AS (SELECT xmltable.*
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FROM y,
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LATERAL xmltable('/data/proc' PASSING doc
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COLUMNS proname name,
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proowner oid,
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procost float,
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pronargs int,
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proargnames text,
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proargtypes text))
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SELECT * FROM z
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EXCEPT SELECT * FROM x;
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CREATE TABLE xmltest2(x xml, _path text);
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INSERT INTO xmltest2 VALUES('<d><r><ac>1</ac></r></d>', 'A');
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INSERT INTO xmltest2 VALUES('<d><r><bc>2</bc></r></d>', 'B');
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INSERT INTO xmltest2 VALUES('<d><r><cc>3</cc></r></d>', 'C');
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INSERT INTO xmltest2 VALUES('<d><r><dc>2</dc></r></d>', 'D');
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SELECT xmltable.* FROM xmltest2, LATERAL xmltable('/d/r' PASSING x COLUMNS a int PATH '' || lower(_path) || 'c');
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SELECT xmltable.* FROM xmltest2, LATERAL xmltable(('/d/r/' || lower(_path) || 'c') PASSING x COLUMNS a int PATH '.');
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SELECT xmltable.* FROM xmltest2, LATERAL xmltable(('/d/r/' || lower(_path) || 'c') PASSING x COLUMNS a int PATH 'x' DEFAULT ascii(_path) - 54);
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