Databases and storage · Comparison
SQL vs NoSQL: PostgreSQL vs MongoDB vs Firestore
Tables or documents is a choice that shapes how you model everything. Here is a SQL database next to the two document databases it is most often weighed against.
3 options · 8 questions side by side · updated
| Compare | PostgreSQL | MongoDB | Firestore |
|---|---|---|---|
| Data shape | Tables with a fixed schema | Flexible JSON-like documents | Documents in collections |
| Relationships | Joins across tables | Embed data, or look it up | Copy data around; no joins |
| Consistency | Strong, with full transactions | Strong per document, transactions available | Strong, with limited transactions |
| Live updates | Through add-ons such as Supabase Realtime | Change streams | Built in, pushed to every client |
| Works offline on devices | No | No | Yes, in the SDKs |
| Query power | Full SQL, good for reports | Rich queries and aggregations | Simple queries only |
| You pay for | Server size or plan | Cluster size or plan | Each read, write and delete |
| Best for | Most apps with users and orders | Varied, nested data | Live, offline-first mobile apps |
How to choose between PostgreSQL, MongoDB and Firestore
- Pick PostgreSQL when data has relationships and must stay correct, which covers most business apps.
- Pick MongoDB when records are naturally nested and vary in shape.
- Pick Firestore for mobile or live apps that need instant sync and offline support without running servers.
The options
- PostgreSQLA powerful open-source relational database that runs as a server and handles everything from a small site to very large, busy products.
- MongoDBA popular document database that stores each record as a JSON-like document instead of a row in a table.
- FirestoreGoogle's hosted document database, part of Firebase, that syncs data to phones and browsers in real time and keeps working offline.
More comparisons
- SQLite vs PostgreSQLBoth are relational and both speak SQL. The real difference is where they run: SQLite is a file inside your app, PostgreSQL is a server your app connects to.
- PostgreSQL vs MySQLThe two most popular open-source relational databases. Either will run a typical web app well; the differences show up at the edges.
- PostgreSQL vs ClickHousePostgreSQL is built for running an app (many small reads and writes); ClickHouse is built for analysing one (a few enormous reads). Plenty of products use both.
- Prisma vs DrizzleThe two most used TypeScript ORMs. Both give you typed queries and migrations; they differ in how close they stay to SQL.
- Supabase vs FirebaseThe two backend platforms most often weighed against each other. Both give you a database, sign-in, storage and functions; the difference starts with the database: PostgreSQL tables against Firestore documents.
- Supabase vs Appwrite vs PocketBaseThree open-source backends that bundle a database, sign-in, storage and live updates. They differ mainly in the database underneath and in how much there is to run yourself.
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