PatientSearchCriteria: identifier "ignoreCase()" restriction adds significant search overhead

When preparing an identifier criteria using an exact match, the following code is used:

if (matchIdentifierExactly) {
    conjuction.add(Restrictions.eq("ids.identifier", identifier).ignoreCase());
}

Looking at the underlying query generated by Hibernate, I'm seeing:

where lower(identifier.identifier) = '123ABC'

That is, the "ignoreCase()" option is causing a "lower" to be applied to the identifier column of the patient identifier table, thereby losing the benefit of the index on the identifier column.

When I remove the "ignoreCase()" and test against a production-sized database, doing an exact-match patient identifier lookup improves from taken 1-2 seconds to being almost instantaneous.

This ignoreCase() should also be irrelevant when using a case-insensitive mysql database.

We should not use the ignoreCase() restriction when Context.getAdministrationService().isDatabaseStringComparisonCaseSensitive() is false.