Some databases supports hints to increase query performance (like Oracle, MySQL, etc). eXo JCR have separate Complex Query implementation for Orcale dialect, that uses query hints to increase performance for few important queries.

To enable this option put next configuration property:

<workspace name="ws" auto-init-root-nodetype="nt:unstructured">

  <container class="org.exoplatform.services.jcr.impl.storage.jdbc.JDBCWorkspaceDataContainer">

    <properties>

      <property name="dialect" value="oracle"/>

      <property name="force.query.hints" value="true" />

      ......

Query hints enabled by default.

eXo JCR uses query hints only for Complex Query Oracle dialect. For all other dialects this parameter is ignored.