Golang TableDescriptor.Dropped方法代碼示例

func filterTableState(tableDesc *sqlbase.TableDescriptor) error {
	switch {
	case tableDesc.Dropped():
		return errTableDropped
	case tableDesc.Adding():
		return errTableAdding
	case tableDesc.State != sqlbase.TableDescriptor_PUBLIC:
		return errors.Errorf("table in unknown state: %s", tableDesc.State.String())
	}
	return nil
}

// runBackfill runs the backfill for the schema changer.
func (sc *SchemaChanger) runBackfill(lease *sqlbase.TableDescriptor_SchemaChangeLease) error {
	if err := sc.ExtendLease(lease); err != nil {
		return err
	}

	// Mutations are applied in a FIFO order. Only apply the first set of
	// mutations. Collect the elements that are part of the mutation.
	var droppedColumnDescs []sqlbase.ColumnDescriptor
	var droppedIndexDescs []sqlbase.IndexDescriptor
	var addedColumnDescs []sqlbase.ColumnDescriptor
	var addedIndexDescs []sqlbase.IndexDescriptor
	// Indexes within the Mutations slice for checkpointing.
	mutationSentinel := -1
	var columnMutationIdx, addedIndexMutationIdx, droppedIndexMutationIdx int

	var tableDesc *sqlbase.TableDescriptor
	if err := sc.db.Txn(context.TODO(), func(txn *client.Txn) error {
		var err error
		tableDesc, err = sqlbase.GetTableDescFromID(txn, sc.tableID)
		return err
	}); err != nil {
		return err
	}
	// Short circuit the backfill if the table has been deleted.
	if tableDesc.Dropped() {
		return nil
	}
	version := tableDesc.Version
	for i, m := range tableDesc.Mutations {
		if m.MutationID != sc.mutationID {
			break
		}
		switch m.Direction {
		case sqlbase.DescriptorMutation_ADD:
			switch t := m.Descriptor_.(type) {
			case *sqlbase.DescriptorMutation_Column:
				addedColumnDescs = append(addedColumnDescs, *t.Column)
				if columnMutationIdx == mutationSentinel {
					columnMutationIdx = i
				}
			case *sqlbase.DescriptorMutation_Index:
				addedIndexDescs = append(addedIndexDescs, *t.Index)
				if addedIndexMutationIdx == mutationSentinel {
					addedIndexMutationIdx = i
				}
			default:
				return errors.Errorf("unsupported mutation: %+v", m)
			}

		case sqlbase.DescriptorMutation_DROP:
			switch t := m.Descriptor_.(type) {
			case *sqlbase.DescriptorMutation_Column:
				droppedColumnDescs = append(droppedColumnDescs, *t.Column)
				if columnMutationIdx == mutationSentinel {
					columnMutationIdx = i
				}
			case *sqlbase.DescriptorMutation_Index:
				droppedIndexDescs = append(droppedIndexDescs, *t.Index)
				if droppedIndexMutationIdx == mutationSentinel {
					droppedIndexMutationIdx = i
				}
			default:
				return errors.Errorf("unsupported mutation: %+v", m)
			}
		}
	}

	// First drop indexes, then add/drop columns, and only then add indexes.

	// Drop indexes.
	if err := sc.truncateIndexes(
		lease, version, droppedIndexDescs, droppedIndexMutationIdx,
	); err != nil {
		return err
	}

	// Add and drop columns.
	if err := sc.truncateAndBackfillColumns(
		lease, version, addedColumnDescs, droppedColumnDescs, columnMutationIdx,
	); err != nil {
		return err
	}

	// Add new indexes.
	if err := sc.backfillIndexes(
		lease, version, addedIndexDescs, addedIndexMutationIdx,
	); err != nil {
		return err
	}

	return nil
}