AddColumnDropBackfillMutation adds a mutation to desc to drop a column.

AddDropIndexMutation adds a mutation to desc to drop an index.

AddNewColumnBackfillMutation adds a mutation to desc to add a column.

AddNewIndexMutation adds a mutation to desc to add an index.

AddPrimaryKeySwapMutation adds a mutation to desc to do a primary key swap.

FetchDescVersionModificationTime fetches the `ModificationTime` of the specified `version` of `tableName`'s table descriptor.

MakeColumnDesc makes a generic column descriptor with the provided id.

MakeTableDesc makes a generic table descriptor with the provided properties.

SetLocalityRegionalByRow sets the LocalityConfig of the table descriptor such that desc.IsLocalityRegionalByRow will return true.