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PostgREST serves a fully RESTful API from any existing PostgreSQL database. It provides a cleaner, more standards-compliant, faster API than you are likely to write from scratch.

Demo postgrest.herokuapp.com | Read Docs | Watch Video

Try making requests to the live demo server with an HTTP client such as postman. The structure of the demo database is defined by begriffs/postgrest-example. You can use it as inspiration for test-driven server migrations in your own projects.

Also try other tools in the PostgREST ecosystem like the ng-admin demo.

Usage

1. Download the binary (latest release) for your platform.

2. Invoke like so:

   postgrest postgres://postgres:foobar@localhost:5432/my_db \
             --port 3000 \
             --schema public \
             --anonymous postgres \
             --pool 200

For more information on valid connection strings see the PostgreSQL docs.

Performance

TLDR; subsecond response times for up to 2000 requests/sec on Heroku free tier. (see the load test)

If you're used to servers written in interpreted languages (or named after precious gems), prepare to be pleasantly surprised by PostgREST performance.

Three factors contribute to the speed. First the server is written in Haskell using the Warp HTTP server (aka a compiled language with lightweight threads). Next it delegates as much calculation as possible to the database including

• Serializing JSON responses directly in SQL
• Data validation
• Authorization
• Combined row counting and retrieval
• Data post in single command (returning *)

Finally it uses the database efficiently with the Hasql library by

• Reusing prepared statements
• Keeping a pool of db connections
• Using the PostgreSQL binary protocol
• Being stateless to allow horizontal scaling

Ultimately the server (when load balanced) is constrained by database performance. This may make it inappropriate for very large traffic load. To learn more about scaling with Heroku and Amazon RDS see the performance guide. Alternatively CitusDB supports Postgres clustering for higher performance.

Other optimizations are possible, and some are outlined in the Future Features.

Security

PostgREST handles authentication (via JSON Web Tokens) and delegates authorization to the role information defined in the database. This ensures there is a single declarative source of truth for security. When dealing with the database the server assumes the identity of the currently authenticated user, and for the duration of the connection cannot do anything the user themselves couldn't. Other forms of authentication can be built on top of the JWT primitive. See the docs for more information.

PostgreSQL 9.5 supports true row-level security. In previous versions it can be simulated with triggers and security-barrier views. Because the possible queries to the database are limited to certain templates using leakproof functions, the trigger workaround does not compromise row-level security.

For example security patterns see the security guide.

Versioning

A robust long-lived API needs the freedom to exist in multiple versions. PostgREST does versioning through database schemas. This allows you to expose tables and views without making the app brittle. Underlying tables can be superseded and hidden behind public facing views. You run an instance of PostgREST per schema and route requests among them with a reverse proxy such as nginx. Learn more here.

Self-documentation

Rather than writing and maintaining separate docs yourself let the API explain its own affordances using HTTP. All PostgREST endpoints respond to the OPTIONS verb and explain what they support as well as the data format of their JSON payload. RAML support is an upcoming feature.

The project uses HTTP itself to communicate other metadata. For instance the number of rows returned by an endpoint is reported by - and limited with - range headers. More about that.

There are more opportunities for self-documentation listed in Future Features.

Data Integrity

Rather than relying on an Object Relational Mapper and custom imperative coding, this system requires you put declarative constraints directly into your database. Hence no application can corrupt your data (including your API server).

The PostgREST exposes HTTP interface with safeguards to prevent surprises, such as enforcing idempotent PUT requests, and

See examples of PostgreSQL constraints and the guide to routing.

Future Features

• Watching endpoint changes with sockets and Postgres pubsub
• Specifying per-view HTTP caching
• Inferring good default caching policies from the Postgres stats collector
• Generating mock data for test clients
• Maintaining separate connection pools per role to avoid "set/reset role" performance penalty
• Describe more relationships with Link headers
• Depending on accept headers, render OPTIONS as RAML or a relational diagram
• ... the other issues

Thanks

I'm grateful to the generous project contributors who have improved PostgREST immensely with their code and good judgement. See more details in the changelog.

The cool logo came from Mikey Casalaina.