<query id="getSdocumentMaxExtraKeyIdx" action="select">
    <tables>
        <table name="document_extra_keys" />
    </tables>
    <columns>
        <column name="max(var_idx)" alias="var_idx" />
    </columns>
    <conditions>
        <condition operation="equal" column="module_srl" var="module_srl" filter="number" notnull="notnull" />
    </conditions>
</query>
