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10.5.3. Iterating Results

Occasionally, you might be able to achieve better performance by executing the query using the iterate() method. This will usually be the case if you expect that the actual entity instances returned by the query will already be in the session or second-level cache. If they are not already cached, iterate() will be slower than list() and might require many database hits for a simple query, usually 1 for the initial select which only returns identifiers, and n additional selects to initialize the actual instances.

// fetch ids
Iterator iter = sess.createQuery("from eg.Qux q order by q.likeliness").iterate();
while ( iter.hasNext() ) {
    Qux qux = (Qux) iter.next();  // fetch the object
    // something we couldn't express in the query
    if ( qux.calculateComplicatedAlgorithm() ) {
        // delete the current instance
        iter.remove();
        // don't need to process the rest
        break;
    }
}

// fetch ids
Iterator iter = sess.createQuery("from eg.Qux q order by q.likeliness").iterate();
while ( iter.hasNext() ) {
    Qux qux = (Qux) iter.next();  // fetch the object
    // something we couldn't express in the query
    if ( qux.calculateComplicatedAlgorithm() ) {
        // delete the current instance
        iter.remove();
        // don't need to process the rest
        break;
    }
}

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10.5.3. Iterating Results

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