Hibernate order by with nulls last

Question

Hibernate used with PostgreSQL DB while ordering desc by a column puts null values higher than not null ones.

SQL99 standard offers keyword \"NULLS LAST\" to declare

Answer 1

Here's my update to the class by (Pascal Thivent):

for (int i = 0; i < orderByNames.length; i++) {
    if (orderByNames[i].trim().length() > 0) {
        String orderName = orderByNames[i].trim().toLowerCase();
        if (orderName.contains("desc")) {
            orderByNames[i] = orderName.replace("desc", "desc NULLS LAST");
        } else {
            orderByNames[i] = orderName.replace("asc", "asc NULLS FIRST");
        }
    }
}

This fixes the problem:

This breaks if sql has limit/offset after order by – Sathish Apr 1 '11 at 14:52

Also here's how you can use this within JPA (hibernate):

Session session = entityManager.unwrap(Session.class);
Session nullsSortingProperlySession = null;
try {
    // perform a query guaranteeing that nulls will sort last
    nullsSortingProperlySession = session.getSessionFactory().withOptions()
        .interceptor(new GuaranteeNullsFirstInterceptor())
        .openSession();
} finally {
    // release the session, or the db connections will spiral
    try {
        if (nullsSortingProperlySession != null) {
            nullsSortingProperlySession.close();
        }
    } catch (Exception e) {
        logger.error("Error closing session", e);
    }
}

I've tested this on postgres and it fixes the 'nulls are higher than non-nulls' issue that we were having.