<dataConfig>
  <dataSource encoding="UTF-8" driver="com.mysql.jdbc.Driver" url="jdbc:mysql://localhost/db" batchSize="-1" user="user" password="pw"/>
    <document name="solrIndex">
        <entity name="artist" query="select id, name from artist">
            <field column="id" name="id_i" />
            <field column="name" name="name_t" />
            <entity name="track" query="select track_id from track_artist where artist_id=${artist.id}">
              <field column="track_id" name="tracks_i" />
            </entity>
        </entity>
        <entity name="label" query="select id, title from label">
            <field column="id" name="id_i" />
            <field column="title" name="title_t" />
            <entity name="track" query="select track_id from track_artist where artist_id in (select artist_id from label_artist where label_id=${label.id})">
              <field column="track_id" name="tracks_i" />
            </entity>
        </entity>
    </document>
</dataConfig>