示例#1
0
func isSchemaChangeRetryError(err error) bool {
	switch err {
	case errDescriptorNotFound:
		return false
	default:
		return !sqlbase.IsIntegrityConstraintError(err)
	}
}
示例#2
0
// Execute the entire schema change in steps. startBackfillNotification is
// called before the backfill starts; it can be nil.
func (sc SchemaChanger) exec(
	startBackfillNotification func() error,
	oldNameNotInUseNotification func(),
) error {
	// Acquire lease.
	lease, err := sc.AcquireLease()
	if err != nil {
		return err
	}
	needRelease := true
	// Always try to release lease.
	defer func(l *sqlbase.TableDescriptor_SchemaChangeLease) {
		// If the schema changer deleted the descriptor, there's no longer a lease to be
		// released.
		if !needRelease {
			return
		}
		if err := sc.ReleaseLease(*l); err != nil {
			log.Warning(err)
		}
	}(&lease)

	// Increment the version and unset tableDescriptor.UpVersion.
	desc, err := sc.MaybeIncrementVersion()
	if err != nil {
		return err
	}

	if desc.GetTable().Deleted() {
		lease, err = sc.ExtendLease(lease)
		if err != nil {
			return err
		}
		// Wait for everybody to see the version with the deleted bit set. When
		// this returns, nobody has any leases on the table, nor can get new leases,
		// so the table will no longer be modified.
		if err := sc.waitToUpdateLeases(); err != nil {
			return err
		}

		// Truncate the table and delete the descriptor.
		if err := sc.truncateAndDropTable(&lease, desc.GetTable()); err != nil {
			return err
		}
		needRelease = false
		return nil
	}

	if desc.GetTable().Renamed() {
		lease, err = sc.ExtendLease(lease)
		if err != nil {
			return err
		}
		// Wait for everyone to see the version with the new name. When this
		// returns, no new transactions will be using the old name for the table, so
		// the old name can now be re-used (by CREATE).
		if err := sc.waitToUpdateLeases(); err != nil {
			return err
		}

		if oldNameNotInUseNotification != nil {
			oldNameNotInUseNotification()
		}
		// Free up the old name(s).
		err := sc.db.Txn(func(txn *client.Txn) error {
			b := client.Batch{}
			for _, renameDetails := range desc.GetTable().Renames {
				tbKey := tableKey{
					sqlbase.ID(renameDetails.OldParentID), renameDetails.OldName}.Key()
				b.Del(tbKey)
			}
			if err := txn.Run(&b); err != nil {
				return err
			}
			return nil
		})
		if err != nil {
			return err
		}

		// Clean up - clear the descriptor's state.
		_, err = sc.leaseMgr.Publish(sc.tableID, func(desc *sqlbase.TableDescriptor) error {
			desc.Renames = nil
			return nil
		})
		if err != nil {
			return err
		}
	}

	// Wait for the schema change to propagate to all nodes after this function
	// returns, so that the new schema is live everywhere. This is not needed for
	// correctness but is done to make the UI experience/tests predictable.
	defer func() {
		if err := sc.waitToUpdateLeases(); err != nil {
			log.Warning(err)
		}
	}()

	if sc.mutationID == sqlbase.InvalidMutationID {
		// Nothing more to do.
		return nil
	}

	// Another transaction might set the up_version bit again,
	// but we're no longer responsible for taking care of that.

	// Run through mutation state machine and backfill.
	err = sc.runStateMachineAndBackfill(&lease, startBackfillNotification)

	// Purge the mutations if the application of the mutations failed due to
	// an integrity constraint violation. All other errors are transient
	// errors that are resolved by retrying the backfill.
	if sqlbase.IsIntegrityConstraintError(err) {
		log.Warningf("reversing schema change due to irrecoverable error: %s", err)
		if errReverse := sc.reverseMutations(); errReverse != nil {
			// Although the backfill did hit an integrity constraint violation
			// and made a decision to reverse the mutations,
			// reverseMutations() failed. If exec() is called again the entire
			// schema change will be retried.
			return errReverse
		}

		// After this point the schema change has been reversed and any retry
		// of the schema change will act upon the reversed schema change.
		if errPurge := sc.runStateMachineAndBackfill(
			&lease, startBackfillNotification,
		); errPurge != nil {
			// Don't return this error because we do want the caller to know
			// that an integrity constraint was violated with the original
			// schema change. The reversed schema change will be
			// retried via the async schema change manager.
			log.Warningf("error purging mutation: %s, after error: %s", errPurge, err)
		}
	}

	return err
}