Page<> vs Slice<> when to use which?
Solution 1
Page
extends Slice
and knows the total number of elements and pages available by triggering a count query. From the Spring Data JPA documentation:
A
Page
knows about the total number of elements and pages available. It does so by the infrastructure triggering a count query to calculate the overall number. As this might be expensive depending on the store used,Slice
can be used as return instead. ASlice
only knows about whether there’s a nextSlice
available which might be just sufficient when walking through a larger result set.
Solution 2
The main difference between Slice
and Page
is the latter provides non-trivial pagination details such as total number of records(getTotalElements()
), total number of pages(getTotalPages()
), and next-page availability status(hasNext()
) that satisfies the query conditions, on the other hand, the former only provides pagination details such as next-page availability status(hasNext()
) compared to its counterpart Page
. Slice
gives significant performance benefits when you deal with a colossal table with burgeoning records.
Let's dig deeper into its technical implementation of both variants.
static class PagedExecution extends JpaQueryExecution {
@Override
protected Object doExecute(final AbstractJpaQuery repositoryQuery, JpaParametersParameterAccessor accessor) {
Query query = repositoryQuery.createQuery(accessor);
return PageableExecutionUtils.getPage(query.getResultList(), accessor.getPageable(),
() -> count(repositoryQuery, accessor));
}
private long count(AbstractJpaQuery repositoryQuery, JpaParametersParameterAccessor accessor) {
List<?> totals = repositoryQuery.createCountQuery(accessor).getResultList();
return (totals.size() == 1 ? CONVERSION_SERVICE.convert(totals.get(0), Long.class) : totals.size());
}
}
If you observe the above code snippet, PagedExecution#doExecute method underlyingly calls PagedExecution#count method to get the total number of records satisfying the condition.
static class SlicedExecution extends JpaQueryExecution {
@Override
protected Object doExecute(AbstractJpaQuery query, JpaParametersParameterAccessor accessor) {
Pageable pageable = accessor.getPageable();
Query createQuery = query.createQuery(accessor);
int pageSize = 0;
if (pageable.isPaged()) {
pageSize = pageable.getPageSize();
createQuery.setMaxResults(pageSize + 1);
}
List<Object> resultList = createQuery.getResultList();
boolean hasNext = pageable.isPaged() && resultList.size() > pageSize;
return new SliceImpl<>(hasNext ? resultList.subList(0, pageSize) : resultList, pageable, hasNext);
}
}
If you observe the above code snippet, to findout whether next set of results present or not (for hasNext()
) the SlicedExecution#doExecute
method always fetch extra one element(createQuery.setMaxResults(pageSize + 1)
) and skip it based on the pageSize condition(hasNext ? resultList.subList(0, pageSize) : resultList
).
- Application:
-
Page
Use when UI/GUI expects to displays all the results at the initial stage of the search/query itself, with page numbers to traverse(ex., bankStatement with pagenumbers)
-
Slice
Use when UI/GUI expects to doesnot interested to show all the results at the initial stage of the search/query itself, but intent to show the records to traverse based on scrolling or next button click event (ex., facebook feed search)
-
Comments
-
Emil Hotkowski almost 2 years
I've read in Spring Jpa Data documentation about two different types of objects when you 'page' your dynamic queries made out of repositories.
Page and Slice
Page<User> findByLastname(String lastname, Pageable pageable); Slice<User> findByLastname(String lastname, Pageable pageable);
So, I've tried to find some articles or anything talking about main difference and different usages of both, how performance changes and how sorting affercts both type of queries.
Does anyone has this type of knowledge, articles or some good source of information?
-
Emil Hotkowski about 6 yearsYeah, i've read that. I was wondering if the difference is bigger than that, but as I see it isn't. That answer seems sufficient : ) thanks to all
-
giannis christofakis over 3 years
Slice has information about whether the next or previous object exists or not.
I find it problematic when I used thePage
-
Mu-Majid almost 3 years@cassiomolin, Does returning a List<Entity> from the repo method is more performant than Slice<Entity>, and of course Page<Entity> ?
-
Victor over 2 yearsBut is there any difference between Page and Slice if both make an order by ?