Schema​

Schema Definition Language​

Migrations are sequences of data definition language (DDL) commands. DDL is a low-level language that tells the database exactly how to change the schema. You typically won't need to write any DDL by hand; the Gel server will generate it for you.

For a full guide on migrations, refer to the Creating and applying migrations guide or the migrations reference section.

Example:

# dbschema/default.gel

type Movie {
  required title: str;
  required director: Person;
}

type Person {
  required name: str;
}

Migrations and DDL​

Gel's baked-in migration system lets you painlessly evolve your schema over time. Just update the contents of your .gel file(s) and use the Gel CLI to create and apply migrations.

$ 

gel migration create

Created dbschema/migrations/00001.edgeql

$ 

gel migrate

Applied dbschema/migrations/00001.edgeql

Migrations are sequences of data definition language (DDL) commands. DDL is a low level language that tells the database how exactly to change the schema. Don't worry, you won't need to write any DDL directly, the Gel server will generate it for you.

For a full guide on migrations, refer to the Creating and applying migrations guide or the migrations reference section.

Instances, branches, and modules​

Gel is like a stack of containers:

• The instance is the running Gel process. Every instance has one or more branches. Instances can be created, started, stopped, and destroyed locally with gel project or low-level gel instance commands.

• A branch is where your schema and data live. Branches map to PostgreSQL databases. Like instances, branches can be conveniently created, removed, and switched with the gel branch commands. Read more about branches in the branches reference (added in 5.0).

• A module is a collection of types, functions, and other definitions. The default module is called default. Modules are used to organize your schema logically. Read more about modules in the modules reference.