org.apache.drill.exec.vector.accessor

Interface TupleWriter

All Superinterfaces:

ColumnWriter

All Known Subinterfaces:

RowSetLoader, RowSetWriter

All Known Implementing Classes:

AbstractTupleWriter, DictEntryWriter, MapWriter, MapWriter.ArrayMapWriter, MapWriter.DummyArrayMapWriter, MapWriter.DummyMapWriter, MapWriter.SingleMapWriter, RowSetLoaderImpl, RowSetWriterImpl

public interface TupleWriter
extends ColumnWriter

Writer for a tuple. A tuple is composed of columns with a fixed order and unique names: either can be used to reference columns. Columns are scalar (simple values), tuples (i.e. maps), or arrays (of scalars, tuples or arrays.) The row itself is just the top-level (anonymous) tuple. Generally, implementers of this interface provide additional services on the implementation of the top-level tuple (often called a "row writer.") Columns are accessible via the associated column writer by name or index. Column indexes are defined by the tuple schema.

Consumers of this interface can define the schema up front, or can define the schema as the write progresses. To avoid redundant checks to see if a column is already defined, consumers can simply ask for a column by name. The column() (and related) methods will throw an (unchecked) TupleWriter.UndefinedColumnException exception if the column is undefined. The consumer can catch the exception, define the column, and fetch the column writer again. New columns may be added via this interface at any time; the new column takes the next available index.

Also provides a convenience method to set the column value from a Java object. The caller is responsible for providing the correct object type for each column. (The object type must match the column accessor type.)

Convenience methods allow getting a column as a scalar, tuple or array. These methods throw an exception if the column is not of the requested type.

See Also:

SingleMapWriter}, the class which this class replaces

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	TupleWriter.UndefinedColumnException Unchecked exception thrown when attempting to access a column writer by name for an undefined columns.

Method Summary

Modifier and Type	Method and Description
int	addColumn(ColumnMetadata column) Add a column to the tuple (row or map) that backs this writer.
int	addColumn(MaterializedField schema)
ArrayWriter	array(int colIndex)
ArrayWriter	array(String colName)
ObjectWriter	column(int colIndex)
ObjectWriter	column(String colName)
DictWriter	dict(int colIndex)
DictWriter	dict(String colName)
boolean	isProjected(String columnName) Reports whether the given column is projected.
ScalarWriter	scalar(int colIndex)
ScalarWriter	scalar(String colName)
void	set(int colIndex, Object value) Write a value to the given column, automatically calling the proper setType method for the data.
int	size()
TupleWriter	tuple(int colIndex)
TupleWriter	tuple(String colName)
TupleMetadata	tupleSchema()
ObjectType	type(int colIndex)
ObjectType	type(String colName)
VariantWriter	variant(int colIndex)
VariantWriter	variant(String colName)

Methods inherited from interface org.apache.drill.exec.vector.accessor.ColumnWriter

copy, isProjected, nullable, schema, setNull, setObject, type

Method Detail

isProjected

boolean isProjected(String columnName)

Reports whether the given column is projected. Useful for clients that can simply skip over unprojected columns.

addColumn

int addColumn(ColumnMetadata column)

Add a column to the tuple (row or map) that backs this writer. Support for this operation depends on whether the client code has registered a listener to implement the addition. Throws an exception if no listener is implemented, or if the add request is otherwise invalid (duplicate name, etc.)

Parameters:

column - the metadata for the column to add

Returns:

the index of the newly added column which can be used to access the newly added writer

addColumn

int addColumn(MaterializedField schema)

tupleSchema

TupleMetadata tupleSchema()

size

int size()

column

ObjectWriter column(int colIndex)

column

ObjectWriter column(String colName)

scalar

ScalarWriter scalar(int colIndex)

scalar

ScalarWriter scalar(String colName)

tuple

TupleWriter tuple(int colIndex)

tuple

TupleWriter tuple(String colName)

array

ArrayWriter array(int colIndex)

array

ArrayWriter array(String colName)

variant

VariantWriter variant(int colIndex)

variant

VariantWriter variant(String colName)

dict

DictWriter dict(int colIndex)

dict

DictWriter dict(String colName)

type

ObjectType type(int colIndex)

type

ObjectType type(String colName)

set

void set(int colIndex,
         Object value)

Write a value to the given column, automatically calling the proper setType method for the data. While this method is convenient for testing, it incurs quite a bit of type-checking overhead and is not suitable for production code.

Parameters:

colIndex - the index of the column to set

value - the value to set. The type of the object must be compatible with the type of the target column