PostgREST

What it is for

PostgREST turns a PostgreSQL schema into a REST API with no code. The first publishing design used it: Trino copied a query result into serving.staging_api.<name> and PostgREST served it, protected by an HS256 token and the role api_reader.

That path is retired. New published APIs are views served live by the platform API (Views and APIs). PostgREST and the serving catalog are still installed and untouched, shown on the status page as “legacy”, and are candidates for removal together.

Where it lives

Binary	/usr/local/bin/postgrest (step 03, checksum checked)
Config	/etc/lake/postgrest/postgrest.conf, jwt.secret
Service	postgrest
Port	3000 (127.0.0.1)
Database	serving, schema api; anonymous role web_anon

Check it

systemctl is-active postgrest
curl -s http://127.0.0.1:3000/            # the OpenAPI document of the schema
curl -s http://127.0.0.1:3000/demo_t      # the demo table made by step 08

How to use it

Only for the demo chain: Trino writes a table into serving.api, then PostgREST must reload its table list:

trino --execute "CREATE TABLE serving.api.demo2 AS SELECT * FROM lake.demo.t"
sudo systemctl kill -s SIGUSR1 postgrest        # reload the schema cache
curl -s http://127.0.0.1:3000/demo2

web_anon has no access to published data; reading it requires a token signed with jwt.secret.

Things that go wrong

Symptom	Likely cause
A new table is not served	The schema cache is old: send SIGUSR1 as above
Every token is rejected	jwt.secret must have no trailing newline
It cannot connect	The authenticator password in postgrest.conf differs from PostgreSQL: re-run step 03