Search for multiple values in an xml column - sql

Question

Environment: SQL Server 2012. Primary and secondary (value) index is built on xml column.
Say I have a table Message with xml column WordIndex. I also have a table Word which has WordId and WordText. Xml for Message.WordIndex has the following schema:
<xs:schema attributeFormDefault="unqualified"
elementFormDefault="qualified"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.example.com">
<xs:element name="wi">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded" name="w">
<xs:complexType>
<xs:sequence>
<xs:element maxOccurs="unbounded" name="p" type="xs:unsignedByte" />
</xs:sequence>
<xs:attribute name="wid" type="xs:unsignedByte" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>
and some data to go with it:
<wi xmlns="http://www.example.com">
<w wid="1">
<p>28</p>
<p>72</p>
<p>125</p>
</w>
<w wid="4">
<p>89</p>
</w>
<w wid="5">
<p>11</p>
</w>
</wi>
I need to search for multiple values in my xml column WordIndex either using OR or AND. What I'm doing is fairly rudimentary, since I'm a n00b in XQuery (taken from debug output, hence real values):
with xmlnamespaces(default 'http://www.example.com')
select
m.Subject,
m.MessageId,
m.WordIndex.query('
let $dummy := 0
return
<word_list>
{
for $w in /wi/w
where $w/#wid=64
return <word wid="64" pos="{data($w/p)}"/>
}
{
for $w in /wi/w
where $w/#wid=70
return <word wid="70" pos="{data($w/p)}"/>
}
{
for $w in /wi/w
where $w/#wid=63
return <word wid="63" pos="{data($w/p)}"/>
}
</word_list>
') as WordPosition
from
Message as m
-- more joins go here ...
where
-- more conditions go here ...
and m.WordIndex.exist('/wi/w[#wid=64]') = 1
and m.WordIndex.exist('/wi/w[#wid=70]') = 1
and m.WordIndex.exist('/wi/w[#wid=63]') = 1
How can this be optimized?

Answer 1

Not sure I understand what your expected results are, but you could make this a bit more generic and data-driven (eg using sql:column or sql:variable). Try something like this:
declare #wids table ( wid INT PRIMARY KEY )
insert into #wids ( wid )
values ( 64 ), ( 70 )
;with xmlnamespaces(default 'http://www.example.com')
select
m.Subject,
m.MessageId,
m.WordIndex.query('
return
<word_list>
{
for $w in /wi/w
where $w/#wid = sql:column("w.wid")
return <word wid="{$w/#wid}" pos="{data($w/p)}"/>
}
</word_list>
') as WordPosition
from
Message as m
cross apply #wids w
where m.WordIndex.exist('wi/w[#wid=sql:column("w.wid")]') = 1