Databases

The yerd db commands manage the databases inside a running SQL service. They apply to the SQL engines only - mysql, mariadb, and postgres. (Redis is a cache and has no SQL databases.) To install, start, or stop the engines themselves, see Services.

The engine must be running

Every yerd db command connects to a live server, so the target service must be installed and started first (yerd service start <svc>). Database operations need no elevation - they connect over the local socket / loopback as a passwordless local-dev superuser.

Commands

Command	Description
yerd db list <SVC>	List the databases in the service (system databases are filtered out).
yerd db create <SVC> <NAME>	Create a new database.
yerd db drop <SVC> <NAME>	Drop a database (irreversible).
yerd db backup <SVC> <NAME> <FILE>	Dump a database to a plain-SQL file.
yerd db restore <SVC> <NAME> <FILE>	Restore a database from a plain-SQL file.

yerd db create mysql my_app
yerd db list mysql
yerd db backup mysql my_app ./my_app.sql
yerd db restore mysql my_app ./my_app.sql
yerd db drop mysql my_app

Database names

create and the other commands validate the database name client-side before connecting, and the daemon validates it again before building any SQL. A name must:

• be non-empty and at most 63 characters (the lowest limit across the engines);
• start with an ASCII letter or underscore (_);
• contain only letters, digits, and underscores.

This strict allowlist is a deliberate security boundary: because the name can never contain quoting or statement separators, the generated SQL is injection-proof by construction.

System databases are protected

Engine-internal databases (mysql, information_schema, performance_schema, sys, postgres, template0, template1) are filtered from db list and cannot be dropped or restored over.

Backup & restore

backup runs the engine's dump tool (mysqldump, mariadb-dump, or pg_dump) and writes plain SQL. The output is streamed to a temporary file next to the destination and atomically renamed into place, so a failed dump never truncates an existing file. A relative <FILE> resolves against the current directory.

restore replays a plain-SQL file back into an existing database through the engine's interactive client (mysql, mariadb, or psql) - so the target database must already exist (yerd db create it first if needed).

# round-trip a database
yerd db create postgres shop
yerd db restore postgres shop ./shop.sql
yerd db backup postgres shop ./shop-$(date +%F).sql

See also

• Services - installing and supervising the engines
• Services & Databases guide - the full model
• yerd-services - database.rs, the pure SQL-admin boundary