On 3/29/2017 6:35 AM, Pablo Anzorena wrote: > I was paginating the results of a query and noticed that some > documents were repeated across pagination buckets of 100 rows. When I > sort by the unique field there is no repeated document but when I sort > by another field then repeated documents appear. I assume is a bug and > it's not the intended behaviour, right?
There is a potential situation that can cause this problem that is NOT a bug. If the field you are sorting on contains duplicate values (same value in multiple documents), then I am pretty sure that the sort order of documents with the same value in the sort field is non-deterministic in these situations: 1) A distributed (sharded) index. 2) When the index contents can change between a request for one page and a request for the next page -- documents being added, deleted, or changed. Because the sort order of documents with the same value can change, one document that may have ended up on the first page on the first query may end up on the second page on the second query. Sorting by a field with no duplicate values (the unique field you mentioned) will always result in the exact same sort order ... but if you add documents that sort to near the start of the sort order between queries, the behavior you have noticed can still happen. If this is what you are encountering, adding secondary sort on the uniqueKey field would probably clear up the problem. If your uniqueKey field is "id", something like this: sort=someField desc,id desc Thanks, Shawn
