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
}