no-force-set-not-null

What It Detects

SET NOT NULL without CHECK constraint pre-validation scans the entire table.

Why It's Dangerous

SET NOT NULL requires scanning every row to verify no NULLs exist, all under ACCESS EXCLUSIVE. Pre-validate with a CHECK constraint using NOT VALID, then the SET NOT NULL is instant.

Bad Example

ALTER TABLE users ALTER COLUMN email SET NOT NULL;

Good Example

ALTER TABLE users ADD CONSTRAINT chk_email_nn
  CHECK (email IS NOT NULL) NOT VALID;
ALTER TABLE users VALIDATE CONSTRAINT chk_email_nn;
ALTER TABLE users ALTER COLUMN email SET NOT NULL;

Configuration

Disable this rule:

# .migrationpilotrc.yml
rules:
  MP018: false

Or change its severity:

# .migrationpilotrc.yml
rules:
  MP018:
    severity: warning