Skip doesn't work in CBLite view?

Mobile Couchbase Lite
,
1

I’m working with Couchbase Server 4.5.0 community edition and Couchbase Mobile 1.4.0 with the Android SDK.

I have a view that allow me to find all documents of a specific type:

private View getCouchbaseFindAllView(Database database) {
        View view = database.getView(FIND_ALL_VIEW_NAME);
        if (view.getMap() == null) {
            Mapper map = new Mapper() {
                @Override
                public void map(Map<String, Object> document, Emitter emitter) {
                    if (isDocumentValid(document, isMetaData(), null);)
                        emitter.emit(document.get(DOCUMENT_TYPE_FIELD), null);
                }
            };
            Reducer reducer = new Reducer() {
                @Override
                public Object reduce(List<Object> keys, List<Object> values, boolean rereduce) {
                    if (rereduce)
                        return com.couchbase.lite.View.totalValues(values);
                    else
                        return values.size();
                }
            };
            view.setMapReduce(map, reducer, FIND_ALL_VIEW_VERSION);
        }
        return view;
    }

And I run a query this way:

protected List<TData> findAll(Database database, Integer limit, Integer skip) {
	View findAllView = getCouchbaseFindAllView(database);
	Query query = findAllView.createQuery();
	if(skip != null)
		query.setSkip(skip);
	if(limit != null)
		query.setLimit(limit);
	query.setMapOnly(true);
	query.setKeys(new ArrayList<Object>(){{add(getDataType());}});
	
	QueryEnumerator rows = query.run();
	List<TData> result = new ArrayList<>();

	for (; rows.hasNext(); ) {
		QueryRow row = rows.next();
		result.add(propertiesToData(row.getDocument().getProperties()));
	}
	
	return result;
}

And here is how I try to do pagination:

//Limit is to avoid to get an OOM error by getting too much patients from the database.
int nbItemsPerPage = 100;
int limit = nbItemsPerPage;
int skip = 0;

List<Patient> patients = couchbase.patientManager().findAll(false, false, null, limit, skip);

while (patients != null && !patients.isEmpty() && nbPatientsDuplicated < totalPatientsToDuplicate) {
    startDuplication(nbOccurrences, duplicator, patients);
    skip = limit;
    limit += nbItemsPerPage;
    if(limit > totalPatientsToDuplicate)
        limit = xFirsts;
    if(skip >= limit)
        break;
    patients = couchbase.patientManager().findAll(false, false, null, limit, skip);
}

But it seems that the skip property is not taken into account because the first time I run the query I receive 100 patients but the 2nd time I receive 200 (so I have a total of 300 patients but I should have a total of 200). Is their something wrong with the way I’m trying to achieve pagination? Or is their a known bug with the skip parameter that I should be aware of?

Inside the function “startDuplication” I’m inserting new patients inside the database, maybe it’s important to mention it.

2

Assuming “limit” is the number of elements to fetch, then shouldn’t that be nbItemsPerPage always?

3

What Priya said — you should be incrementing skip, not limit, in the loop.

4

Well thank’s. I was assuming that limit was the first x documents so if I have a limit of 1000 and skip of 500 it will take the 1000 first but skip 500 of them -> result = 500 doc. But I was totally wrong. Thank you for your help!

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