-- Stars: a user's bookmark on a repo. A row goes with either the user or the repo.
-- The primary key serves "repos starred by a user"; the index serves the per-repo count.

CREATE TABLE stars (
    user_id    TEXT NOT NULL REFERENCES users(id) ON DELETE CASCADE,
    repo_id    TEXT NOT NULL REFERENCES repos(id) ON DELETE CASCADE,
    created_at TEXT NOT NULL,
    PRIMARY KEY (user_id, repo_id));
CREATE INDEX stars_repo_id ON stars(repo_id);