Firebase 文档读取优化

Question

I'm using firebase firestore for my react-native app, I'm creating a app that will send user geolocation to firestore and generate heatmap, and the app will send user's location every 5 mins, my data looks like this

Right now I have about 1000 documents, every time I refresh the app, it will try to fetch all coords to generate the heatmap.

The problem I'm having is when it generate the heatmap, it will need to read all 1000 documents, what if I have 5000 coords/documents, and I have 10 users to use it, it will reach the documents read limit in firebase free plan which is 50k/day.

I know I can pay some money to increase the read limit, but just wondering if any one run into this and find optimize way to solve it. Thanks!

Answer 1

I don't know all the constraints of your application, but you could possibly store all the coordinates of one month in one document, in an array, reducing by 8928 the number of document reads.

If I did the maths corrrecly, based on this documentation page https://firebase.google.com/docs/firestore/storage-size which explains the Storage size calculations, you can calculate that a doc with 3 arrays named lat , long and ts under your coords collection which stores the data for 288*31 triplet values (288 = every 5 minutes in one day) will have a size of maximum 857,088 bytes, which is under the maximum possible size for a document (ie 1,048,576 bytes) as presented here: https://firebase.google.com/docs/firestore/quotas

Of course, you'll have to deal with the array fields but for that you can use firebase.firestore.FieldValue.arrayUnion(); , see https://firebase.google.com/docs/firestore/manage-data/add-data#update_elements_in_an_array