Lazy loading with JPA criterea - primefaces

Question

I implemented a generic solution for using lazy loading primefaces datatables using JPA Criterea.
However I am still having some doubts with thie implemented solution whenever we deal with several Joins (say for example an entity User that has relation with other entities like Account, Address, Department.....in addition to raw type properties like: String username, Date birthdate...etc).
I tested this solution but I am having some delays while loading huge number of data (however the solution is supposed to load only a limited number of rows specified by PageSize coming from datatable), so:
How to improve the performance of this solution?
How to be sure the number of loaded data is the one specified in the Pagesize?
Can you check the count() method and tell if it counts the number of result rows without loading all the data?
And most importantly how to use this solution in order to be generic with filters coming from Search forms (I mean how to use this sae generic method and give search critereas from a search form with multi search fields)?
Please I need your answer on the above mentioned questions especially the last one.
Here is the code:
public <T extends Object> List<T> search(Class<T> type, int first, int pageSize, String sortField, SortOrder sortOrder, Map<String, String> filters){
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<T> q = cb.createQuery(type);
Root<T> root=q.from(type);
q.select(root);
//Sorting
if (sortField != null && !sortField.isEmpty()) {
String[] sortingField = sortField.split("\\.", 2);
Path path = sortingField.length == 1 ? root.get(sortingField[0]): root.join(sortingField[0]).get(sortingField[1]);
if (sortOrder.equals(SortOrder.ASCENDING)) {
q.orderBy(cb.asc(path));
} else if (sortOrder.equals(SortOrder.DESCENDING)) {
q.orderBy(cb.desc(path));
}
}
// Filtering
Predicate filterCondition = cb.conjunction();
String wildCard = "%";
for (Map.Entry<String, String> filter : filters.entrySet()) {
String[] filterField = filter.getKey().split("\\.", 2);
Path path = filterField.length == 1 ? root.get(filterField[0]): root.join(filterField[0]).get(filterField[1]);
filterCondition = cb.and(filterCondition, filter.getValue().matches("[0-9]+")
? cb.equal(path, Long.valueOf(filter.getValue()))
: cb.like(path, wildCard + filter.getValue() + wildCard));
}q.where(filterCondition);
//Pagination
TypedQuery<T> s = entityManager.createQuery(q);
if (pageSize >= 0){
s.setMaxResults(pageSize);
}
if (first >= 0){
s.setFirstResult(first);
}
log.info("\n\n\n");
log.info("XXXXXXXXXxX");
log.info("=> CommonRepository - Total number of rows returned: ");
log.info("XXXXXXXXXXX");
log.info("\n\n\n");
return s.getResultList();
}
public <T extends Object> int count(Class<T> type, Map<String, String> filters){
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Long> cq = cb.createQuery(Long.class);
Root<T> root=cq.from(type);
// Filtering
Predicate filterCondition = cb.conjunction();
String wildCard = "%";
for (Map.Entry<String, String> filter : filters.entrySet()) {
String[] filterField = filter.getKey().split("\\.", 2);
Path path = filterField.length == 1 ? root.get(filterField[0]): root.join(filterField[0]).get(filterField[1]);
filterCondition = cb.and(filterCondition, filter.getValue().matches("[0-9]+")
? cb.equal(path, Long.valueOf(filter.getValue()))
: cb.like(path, wildCard + filter.getValue() + wildCard));
}cq.where(filterCondition);
cq.select(cb.count(root));
return entityManager.createQuery(cq).getSingleResult().intValue();
}