Idempotency Guards

Check names: IdempotencyCreateCheck, IdempotencyIndexCheck, IdempotencyAlterCheck, IdempotencyDropCheck

Lock type: — (retry safety)

Bad

Statements without idempotency guards can fail when a migration is retried after partial success.

CREATE TABLE users (id BIGINT PRIMARY KEY);
CREATE INDEX CONCURRENTLY users_email_idx ON users(email);
ALTER TABLE users ADD COLUMN email TEXT;

DROP TABLE users;
DROP INDEX users_email_idx;
ALTER TABLE users DROP COLUMN email;

Good

Add guards so statements can be re-run safely.

CREATE TABLE IF NOT EXISTS users (id BIGINT PRIMARY KEY);
CREATE INDEX CONCURRENTLY IF NOT EXISTS users_email_idx ON users(email);
ALTER TABLE users ADD COLUMN IF NOT EXISTS email TEXT;

DROP TABLE IF EXISTS users;
DROP INDEX IF EXISTS users_email_idx;
ALTER TABLE users DROP COLUMN IF EXISTS email;

Covered Operations

• CREATE TABLE requires IF NOT EXISTS
• CREATE INDEX (including CONCURRENTLY) requires IF NOT EXISTS
• ALTER TABLE ... ADD COLUMN requires IF NOT EXISTS
• DROP TABLE requires IF EXISTS
• DROP INDEX requires IF EXISTS
• ALTER TABLE ... DROP COLUMN requires IF EXISTS