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Javascript – Firebase Firestore Query Index Issue with Multiple Filters and Combinations

I am building a website that uses pagination and filtering of some data.

if (eventType) query = query.where('general.eventType', '==', eventType); 
if (price) query = query.where('general.eventTicketPrice', price == "free" ? '==' : '>=', 0);
if (startDate) query = query.where('general.eventDates.start', '>=', new Date(startDate));
if (endDate) query = query.where('general.eventDates.start', '<=', new Date(endDate));
if (location) query = query.where('general.location.city', '==', location);
if (participation) query = query.where('general.locationType', '==', participation);
...
...

I have about 20 filters that I use, and whenever I select any filter the firebase needs me to create a new index. I am assuming that I need to do this for each combination of filters. I basically made a combination generator that tries each query and gives me the URL for creating the index, but there are A LOT of them. Like thousands so naturally I don’t want to generate them manually.

Is there a way to fix this issue?

I thought about getting all the documents and then filtering manually. It would be easy to implement but may be costly and maybe high latency (idk). Currently, there are not many documents but I want to be able to query hundreds maybe thousands of documents.

What are some recommendations for this type of issue?

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2

Answers


  1. 0

    A general rule for Firestore is that it every query is always executed against one or more indexes, but that doesn’t mean you need a separate index for every query. From the documentation on index merging:

    Although Cloud Firestore uses an index for every query, it doesn’t necessarily require one index per query. For queries with multiple equality (==) clauses and, optionally, an orderBy clause, Cloud Firestore can re-use existing indexes. Cloud Firestore can merge the indexes for simple equality filters to build the composite indexes needed for larger equality queries.

    In your case, you might need to move your relational conditions (>=, <=, etc) to the end of the query, but could then potentially depend on the existing single field indexes for most equality checks.

    Note: queries that use merged indexes will typically perform slower than if you’d create a dedicated composite index for them. So you’ll want to keep an eye on query performance, and optimize as needed.

    I actually recorded a short video about an instance where this happened during Google I/O last year, which you can see here.

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  2. 0

    Not clear on what is broken in your case, but generally speaking:

    Cloud Firestore ensures query performance by requiring an index for
    every query. The indexes required for the most basic queries are
    automatically created for you    .

    https://firebase.google.com/docs/firestore/query-data/indexing

    Then at https://firebase.google.com/docs/firestore/query-data/queries#query_limitations …

    Query limitations

    The following list summarizes Cloud Firestore query limitations:

    • Cloud Firestore provides support for logical OR queries through the or, in, and array-contains-any operators. These queries are limited to
      30 disjunctions based on the query’s disjunctive normal form.
    • You can use at most one array-contains clause per disjunction (or group). You can’t combine array-contains with array-contains-any in
      the same disjunction.
    • You can’t combine not-in with in, array-contains-any, or or in the same query.
    • Only a single not-in or != is allowed per query. not-in supports up to 10 comparison values.
    • The sum of filters, sort orders, and parent document path (1 for a subcollection, 0 for a root collection) in a query cannot exceed 100.
      This is calculated based on the disjunctive normal form of the query.
    • A query with an inequality filter on a field implies ordering by that field and filters for existence of that field.

    Limits on OR queries

    To prevent a query from becoming too computationally expensive, Cloud Firestore limits how many AND and OR
    clauses you can combine. To apply this limit, Cloud Firestore converts
    queries that perform logical OR operations (or, in, and
    array-contains-any) to disjunctive normal form (also known as an OR of
    ANDs). Cloud Firestore limits a query to a maximum of 30
    disjunctions in disjunctive normal form    .

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