Does FirestorePagingAdapter fetch document in pages or all document at once and then apply paging?

Question

I am using Firestore to store my data. Now I want to fetch perticular collection from it. I am using FirestorePagingAdapter to do this.

Scenario: I am querying Firestore to fetch all documents from perticular collection, lets say posts(collection) contain 100 documents, and FirestorePagingAdapter configured as below

-setPrefetchDistance(2)
-setInitialLoadSizeHint(10)
-setPageSize(10)

Now my doubt is will FirestorePagingAdapter fetch all documents at once (means all 100 doc once) then then apply paging or query Firestore according to page size (10 at a time), and when reaches to bottom, will fetch next 10 doc?

Basically I want to reduce read operations in Firestore.

Please help me here.

Thanks...I gone though it but not able to understand. Could you please here. — Shendre Kiran, Mar 21 '19 at 06:29
https://github.com/firebase/FirebaseUI-Android/blob/master/firestore/README.md#firestorepagingadapter-lifecycle — Ranjan, Mar 21 '19 at 06:31

Alex Mamo · Accepted Answer · 2019-03-21T08:15:11.540

1

will FirestorePagingAdapter fetch all documents at once (means all 100 doc once) then then apply paging

Definitely not.

query Firestore according to page size (10 at a time), and when reaches to bottom, will fetch next 10 doc?

Definitely yes. So first time you are billed with 10 read operations and once you load 10 more items, you are billed with 10 more read operations. So if you load only two parts of your items (20 items) you'll be billed with 20 read operation and not with 100.

edited Mar 21 '19 at 08:15

answered Mar 21 '19 at 06:55

Alex Mamo

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I think you meant to write *"... and not with 100"*. – AdrianHHH Mar 21 '19 at 08:09
@AdrianHHH Oh yes, you're right. My bad. Just updated my answer. Thanks Adrian. – Alex Mamo Mar 21 '19 at 08:15
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@AlexMamo Done..! – Shendre Kiran Mar 22 '19 at 19:33

Does FirestorePagingAdapter fetch document in pages or all document at once and then apply paging?

1 Answers1