About Firestore Query Builder

Build Firestore queries with constraints and filters. Part of the DevTools Surf developer suite. Browse more tools in the Database Tools collection.

Use Cases

• Build compound Firestore queries with multiple where() clauses
• Design efficient collection structure with index requirements in mind
• Generate query code for JavaScript, Python, or Java Firebase SDKs
• Prototype real-time listener queries before building Flutter or React applications

Tips

• Firestore queries require a composite index for any query combining ordering with filtering on different fields — the builder shows an index definition to create if needed
• Use the 'collection group query' mode to query across subcollections with the same name throughout your entire Firestore database
• Limit large result sets with the limit() and startAfter() methods — unbounded queries on large collections are expensive and potentially dangerous for billing

Fun Facts

• Firebase Firestore was launched by Google in 2017 as a successor to Firebase Realtime Database. Both are real-time databases, but Firestore uses a document-collection model (similar to MongoDB) instead of a flat JSON tree.
• Firestore charges per document read, write, and delete — not by storage or time. A document read costs $0.06 per 100,000 reads. At scale, poorly designed queries that scan unnecessarily can generate significant costs. Efficient query design is both a performance and cost concern.
• Firestore's real-time listeners use WebSocket connections to push updates to clients without polling. The backend infrastructure is built on Google's Bigtable and Spanner — the same infrastructure that powers Google's own products.

FAQ

Why do Firestore queries require composite indexes?

Firestore uses server-side indexes to execute queries efficiently. A single-field index handles simple queries. When you combine a where() on one field with an orderBy() on a different field, Firestore needs a composite index to combine both efficiently. The Firebase Console generates the index creation link automatically.

What are the query limitations in Firestore?

No JOINs across collections. No OR queries across different fields (use multiple queries and merge). No full-text search (use Algolia, Elasticsearch, or Typesense). Range queries (>, <, >=, <=) only on one field per query. These limitations drive denormalized data modeling.

What is the difference between Firestore and Firebase Realtime Database?

Firestore uses documents/collections with richer queries. Realtime Database stores data as a single JSON tree with simpler queries but lower cost for high-frequency small writes. For new projects, Firestore is recommended. Realtime Database has lower latency for simple key-value access.