-- +goose Up
ALTER TABLE flashcard ADD COLUMN public_id INTEGER NOT NULL DEFAULT 0;
ALTER TABLE flashcard ADD COLUMN version INTEGER NOT NULL DEFAULT 1;
UPDATE flashcard SET public_id = _id WHERE public_id = 0;
CREATE UNIQUE INDEX IF NOT EXISTS idx_flashcard_public_id_version ON flashcard(public_id, version);

-- +goose Down
DROP INDEX IF EXISTS idx_flashcard_public_id_version;
ALTER TABLE flashcard DROP COLUMN version;
ALTER TABLE flashcard DROP COLUMN public_id;