Backend reference

One option chooses the engine. Exactly one backend is active per process; there is no multi-engine mode.

db-backend = "sqlite"
db-uri     = "file:./example.sqlite"

The connection string is the standard PostgREST db-uri, interpreted by the selected backend's driver. dbrest does not invent a wrapper around the driver's own format.

SQLite

db-backend = "sqlite"
db-uri     = "file:app.db?_journal=WAL&_busy_timeout=5000"

The db-uri is a file path or a file: URI rather than a server address. Pragmas such as WAL journaling and busy_timeout travel as URI parameters. The driver is pure Go and cgo-free, so SQLite runs anywhere Go runs with nothing to install. This is the reference backend and the one this guide uses.

PostgreSQL

db-backend = "postgres"
db-uri     = "postgres://user:pass@host:5432/dbname?sslmode=require"

Parsed by pgx. The supported floor is PostgreSQL 13, since PostgREST v14 dropped end-of-life 12. This is the reference oracle the conformance harness diffs against. The dialect and version-computed capabilities have landed; the live data plane is a follow-on slice.

MySQL and MariaDB

db-backend = "mysql"
db-uri     = "user:pass@tcp(host:3306)/dbname?parseTime=true&loc=UTC"

A go-sql-driver/mysql DSN. parseTime=true is recommended. The dialect and capabilities have landed, the first real divergence from the PostgreSQL oracle: an IS NULL sort key for NULL placement, a no-conflict-target upsert, restricted cast targets, REGEXP_LIKE, and MATCH ... AGAINST boolean-mode full text. The driver data plane is a follow-on slice.

SQL Server

db-backend = "sqlserver"
db-uri     = "sqlserver://user:pass@host:1433?database=dbname"

A URL or ADO keyword connection string, parsed by go-mssqldb. The dialect and capabilities have landed: bracket-quoted identifiers, named @pN placeholders, OFFSET/FETCH paging that injects an ORDER BY when the client gave none, a CASE NULL sort key, OUTPUT in place of RETURNING, a multi-statement upsert, and CONTAINS/FREETEXT full text, with native roles, Row Level Security, and a session-context store. The driver data plane is a follow-on slice.

MongoDB

db-backend = "mongodb"
db-uri     = "mongodb://user:pass@host:27017/dbname?replicaSet=rs0"

Parsed by the official Mongo driver. The URI selects the cluster; the exposed database comes from the URI path or from db-schemas. This is the one engine that does not use the SQL compiler: it lowers a filter to a $match query document, a read to a $match/$sort/$skip/$limit/$project pipeline, casts to $convert, and NULLS placement to an $addFields sort key. Array and range operators are Unsupported, and the security model is emulated app-side. Because MongoDB has no fixed schema and no foreign keys, the declared-schema and declared-relationships options carry the metadata the introspector would otherwise read. The live data plane is a follow-on slice.

Backends that need a running server

For local testing against PostgreSQL, MySQL, MariaDB, SQL Server, or MongoDB, the repository's docker/ directory has a Podman compose file per backend and a docker/all/ that runs them together. MongoDB runs as a single-node replica set so its transaction capability resolves the way a production deployment would.

podman compose -f docker/postgres/compose.yaml up -d   # one engine
podman compose -f docker/all/compose.yaml up -d        # all of them