Method cutOverTwoStep

go/logic/migrator.go:956–985

cutOverTwoStep will lock down the original table, execute what's left of last DML entries, and **non-atomically** swap original->old, then new->original. There is a point in time where the "original" table does not exist and queries are non-blocked and failing.

()

// There is a point in time where the "original" table does not exist and queries are non-blocked
// and failing.
func (mgtr *Migrator) cutOverTwoStep() (err error) {
	atomic.StoreInt64(&mgtr.migrationContext.InCutOverCriticalSectionFlag, 1)
	defer atomic.StoreInt64(&mgtr.migrationContext.InCutOverCriticalSectionFlag, 0)
	atomic.StoreInt64(&mgtr.migrationContext.AllEventsUpToLockProcessedInjectedFlag, 0)

	if err := mgtr.retryOperation(mgtr.applier.LockOriginalTable); err != nil {
		return err
	}

	if err := mgtr.retryOperation(mgtr.waitForEventsUpToLock); err != nil {
		return err
	}
	// If we need to create triggers we need to do it here (only create part)
	if mgtr.migrationContext.IncludeTriggers && len(mgtr.migrationContext.Triggers) > 0 {
		if err := mgtr.retryOperation(mgtr.applier.CreateTriggersOnGhost); err != nil {
			return err
		}
	}
	if err := mgtr.retryOperation(mgtr.applier.SwapTablesQuickAndBumpy); err != nil {
		return err
	}
	if err := mgtr.retryOperation(mgtr.applier.UnlockTables); err != nil {
		return err
	}

	lockAndRenameDuration := mgtr.migrationContext.RenameTablesEndTime.Sub(mgtr.migrationContext.LockTablesStartTime)
	renameDuration := mgtr.migrationContext.RenameTablesEndTime.Sub(mgtr.migrationContext.RenameTablesStartTime)
	mgtr.migrationContext.Log.Debugf("Lock & rename duration: %s (rename only: %s). During mgtr time, queries on %s were locked or failing", lockAndRenameDuration, renameDuration, sql.EscapeName(mgtr.migrationContext.OriginalTableName))
	return nil
}

// atomicCutOver
func (mgtr *Migrator) atomicCutOver() (err error) {