PostgreSQL
Database Design
The PostgreSQL database is designed to store GitLab’s core data, such as users, projects, repositories, and CI/CD pipelines. It leverages the power of a relational database system to provide a structured and efficient storage mechanism.
Schema: The schema defines the structure of the database, including tables, columns, and relationships between them. The GitLab schema is extensive and well-documented.
Tables:
users: Stores information about GitLab users.projects: Stores information about GitLab projects.repositories: Stores information about GitLab repositories.ci_builds: Stores information about CI/CD builds.ci_pipelines: Stores information about CI/CD pipelines.
Relationships:
- Users can have multiple projects.
- Projects can have multiple repositories.
- Repositories can have multiple CI/CD pipelines.
Data Types:
integer: Stores whole numbers.text: Stores strings of text.timestamp with time zone: Stores timestamps with time zone information.boolean: Stores true or false values.
Querying
PostgreSQL provides a powerful SQL language for querying the database.
Syntax:
SELECT column1, column2
FROM table_name
WHERE condition;
Examples:
- Retrieve all users:
SELECT *
FROM users;
- Retrieve projects owned by a specific user:
SELECT *
FROM projects
WHERE owner_id = 123;
- Retrieve CI/CD pipelines for a specific project:
SELECT *
FROM ci_pipelines
WHERE project_id = 456;
Migrations
GitLab uses migrations to manage database schema changes over time.
Process:
- Create a migration file.
- Define the schema changes in the migration file.
- Run the migrations to apply the changes to the database.
Example:
class AddNewColumnToUsers < ActiveRecord::Migration[6.1]
def change
add_column :users, :new_column, :string
end
end
