[Exist-open] How to index an XML file for towns and zipcodes?

[Grégoire C. <gco...@gm...>]

Hi,

I have a XML file which contains 35,000 towns like this :

<towns>
  <town>
    <name>Townville upon River</name>
    <zipcode>12345</zipcode>
    <alt_names>
      <name>townville-upon-river</name>
      <name>townville</name>
    </alt_names>
  </town>
  ...
</towns>

The use-case is a "Google Suggest" functionality. That is, when a user
adds a caracter in the XForm, a request is sent to the server, where the
string ($place) is converted lowercase and spaces are all replaced by
hyphens, so that it can be compared with the alternate names found in
alt_names/name. The XQuery is :

for $town in
collection("/db/towns")//town[starts-with(alt_names/name,$place)]
order by $town/name ascending
return
  <town>
       {$town/name}
       {$town/zipcode}
  </town>

Unfortunately, the performance was poor by default (600 ms by request),
so I tried to add a "collection.xconf" which contains :

<collection xmlns="http://exist-db.org/collection-config/1.0">
    <index>
        <fulltext default="none" attributes="false">

        </fulltext>
        <lucene>
            <text qname="name" type="xs:string"/>
            <text qname="zipcode" type="xs:integer"/>
        </lucene>
        <ngram qname="alt_names/name"/>
    </index>
</collection>

Now the performance is... even worse, at around 1 second per request.
What should I add to my "xconf" file to improve the performance?

Best regards,
Gregoire