Firestore errorFirestore: in query has more than 30 values

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Why the query fails, and the fix

1. 01

   The list has more than 30 values

   “Use the in operator to combine up to 30 equality (==) clauses on the same field with a logical OR.” Firebase, Simple and compound queries (in)

   An in filter on a list of ids, such as the people a user follows, works until the list passes 30. Split it and query each part.

   // Web SDK
   import { collection, query, where, getDocs, documentId } from 'firebase/firestore';
   
   const unique = [...new Set(ids)];
   const chunks = [];
   for (let i = 0; i < unique.length; i += 30) chunks.push(unique.slice(i, i + 30));
   const snaps = await Promise.all(
     chunks.map((c) => getDocs(query(collection(db, 'users'), where(documentId(), 'in', c)))),
   );
   const users = snaps.flatMap((s) => s.docs.map((d) => ({ id: d.id, ...d.data() })));

2. 02

   Two filters multiply the count

   “These queries are limited to 30 disjunctions based on the query's disjunctive normal form. This limit is fixed and cannot be adjusted.” Firebase, Simple and compound queries (Limitations)

   Firestore counts the or, in and array-contains-any parts together. Two in filters with 6 values each make 36 combinations, which is over the limit even though each list is short. If the query has another in or or, divide 30 by that part’s size to get the chunk size.

3. 03

   not-in has a lower limit

   “not-in supports up to 10 comparison values.” Firebase, Simple and compound queries (Limitations)

   not-in allows only 10 values. To hide more, filter them out in the app after the query, or store a flag on the documents and filter on that.

4. 04

   The query shape doesn’t fit the data

   If a screen always needs hundreds of ids, change the data instead: store the owner or group id on each document and query it with one == filter, or keep a list on a single document. On a server, the Admin SDK getAll() reads many known documents in one call. Chunked reads still cost one read per document.

Checked against the vendor’s docs on November 9, 2026: Firebase docs: Simple and compound queries.

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Related: Firestore query requires an index · Firestore quota exceeded · Firestore invalid document reference · Cloud Firestore API disabled