-- Migration 022: Composite query indexes for notes + author_id column
-- Optimizes author-scoped and project-scoped date-range queries on notes.
-- Adds discussion JOIN indexes and immutable author identity column.

-- Composite index for author-scoped queries (who command, notes --author)
CREATE INDEX IF NOT EXISTS idx_notes_user_created
ON notes(project_id, author_username COLLATE NOCASE, created_at DESC, id DESC)
WHERE is_system = 0;

-- Composite index for project-scoped date-range queries
CREATE INDEX IF NOT EXISTS idx_notes_project_created
ON notes(project_id, created_at DESC, id DESC)
WHERE is_system = 0;

-- Discussion JOIN indexes
CREATE INDEX IF NOT EXISTS idx_discussions_issue_id ON discussions(issue_id);
CREATE INDEX IF NOT EXISTS idx_discussions_mr_id ON discussions(merge_request_id);

-- Immutable author identity column (GitLab numeric user ID)
ALTER TABLE notes ADD COLUMN author_id INTEGER;
CREATE INDEX IF NOT EXISTS idx_notes_author_id ON notes(author_id) WHERE author_id IS NOT NULL;