Package org.apache.drill.exec.vector.accessor.writer

Class AbstractTupleWriter

java.lang.Object
org.apache.drill.exec.vector.accessor.writer.AbstractTupleWriter
All Implemented Interfaces:
ColumnWriter, TupleWriter, WriterEvents, WriterPosition
Direct Known Subclasses:
DictEntryWriter, MapWriter, RowSetLoaderImpl, RowSetWriterImpl
public abstract class AbstractTupleWriter extends Object implements TupleWriter, WriterEvents
Implementation for a writer for a tuple (a row or a map.) Provides access to each column using either a name or a numeric index.

A tuple maintains an internal state needed to handle dynamic column additions. The state identifies the amount of "catch up" needed to get the new column into the same state as the existing columns. The state is also handy for understanding the tuple lifecycle. This lifecycle works for all three cases of:

  • Top-level tuple (row).
  • Nested tuple (map).
  • Array of tuples (repeated map).
Specifically, the transitions, for batch, row and array events, are:
Public APITuple EventState Transition Child Event
(Start state) — IDLE —
startBatch() startWrite() IDLE → IN_WRITE startWrite()
start() (new row) startRow() IN_WRITE → IN_ROW startRow()
start() (without save) restartRow() IN_ROW → IN_ROW restartRow()
save() (array) saveValue() IN_ROW → IN_ROW saveValue()
save() (row) saveValue() IN_ROW → IN_ROW saveValue()
saveRow() IN_ROW → IN_WRITE saveRow()
end batch — IN_ROW → IDLE endWrite()
— IN_WRITE → IDLE endWrite()
Notes:
  • For the top-level tuple, a special case occurs with ending a batch. (The method for doing so differs depending on implementation.) If a row is active, then that row's values are discarded. Then, the batch is ended.

  • Field Details

  • Constructor Details

  • Method Details

    • type

      public ObjectType type()
      Description copied from interface: ColumnWriter
      Return the object (structure) type of this writer.
      Specified by:
      type in interface ColumnWriter
      Returns:
      type indicating if this is a scalar, tuple or array

    • bindIndex

      protected void bindIndex(ColumnWriterIndex index, ColumnWriterIndex childIndex)

    • bindIndex

      public void bindIndex(ColumnWriterIndex index)
      Description copied from interface: WriterEvents
      Bind the writer to a writer index.
      Specified by:
      bindIndex in interface WriterEvents
      Parameters:
      index - the writer index (top level or nested for arrays)

    • rowStartIndex

      public int rowStartIndex()
      Description copied from interface: WriterPosition
      Position within the vector of the first value for the current row. Note that this is always the first value for the row, even for a writer deeply nested within a hierarchy of arrays. (The first position for the current array is not exposed in this API.)
      Specified by:
      rowStartIndex in interface WriterPosition
      Returns:
      the vector offset of the first value for the current row

    • addColumnWriter

      public int addColumnWriter(AbstractObjectWriter colWriter)
      Add a column writer to an existing tuple writer. Used for implementations that support "live" schema evolution: column discovery while writing. The corresponding metadata must already have been added to the schema.
      Parameters:
      colWriter - the column writer to add

    • isProjected

      public boolean isProjected(String columnName)
      Description copied from interface: TupleWriter
      Reports whether the given column is projected. Useful for clients that can simply skip over unprojected columns.
      Specified by:
      isProjected in interface TupleWriter

    • addColumn

      public int addColumn(ColumnMetadata column)
      Description copied from interface: TupleWriter
      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.)
      Specified by:
      addColumn in interface TupleWriter
      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

      public int addColumn(MaterializedField field)
      Specified by:
      addColumn in interface TupleWriter

    • tupleSchema

      public TupleMetadata tupleSchema()
      Specified by:
      tupleSchema in interface TupleWriter

    • size

      public int size()
      Specified by:
      size in interface TupleWriter

    • nullable

      public boolean nullable()
      Description copied from interface: ColumnWriter
      Whether this writer allows nulls. This is not as simple as checking for the TypeProtos.DataMode.OPTIONAL type in the schema. List entries are nullable, if they are primitive, but not if they are maps or lists. Unions are nullable, regardless of cardinality.
      Specified by:
      nullable in interface ColumnWriter
      Returns:
      true if a call to ColumnWriter.setNull() is supported, false if not

    • setNull

      public void setNull()
      Description copied from interface: ColumnWriter
      Set the current value to null. Support depends on the underlying implementation: only nullable types support this operation. throws IllegalStateException if called on a non-nullable value.
      Specified by:
      setNull in interface ColumnWriter

    • startWrite

      public void startWrite()
      Description copied from interface: WriterEvents
      Start a write (batch) operation. Performs any vector initialization required at the start of a batch (especially for offset vectors.)
      Specified by:
      startWrite in interface WriterEvents

    • startRow

      public void startRow()
      Description copied from interface: WriterEvents
      Start a new row. To be called only when a row is not active. To restart a row, call WriterEvents.restartRow() instead.
      Specified by:
      startRow in interface WriterEvents

    • endArrayValue

      public void endArrayValue()
      Description copied from interface: WriterEvents
      End a value. Similar to WriterEvents.saveRow(), but the save of a value is conditional on saving the row. This version is primarily of use in tuples nested inside arrays: it saves each tuple within the array, advancing to a new position in the array. The update of the array's offset vector based on the cumulative value saves is done when saving the row.
      Specified by:
      endArrayValue in interface WriterEvents

    • restartRow

      public void restartRow()
      Description copied from interface: WriterEvents
      During a writer to a row, rewind the the current index position to restart the row. Done when abandoning the current row, such as when filtering out a row at read time.
      Specified by:
      restartRow in interface WriterEvents

    • saveRow

      public void saveRow()
      Description copied from interface: WriterEvents
      Saves a row. Commits offset vector locations and advances each to the next position. Can be called only when a row is active.
      Specified by:
      saveRow in interface WriterEvents

    • preRollover

      public void preRollover()
      Description copied from interface: WriterEvents
      The vectors backing this vector are about to roll over. Finish the current batch up to, but not including, the current row.
      Specified by:
      preRollover in interface WriterEvents

    • postRollover

      public void postRollover()
      Description copied from interface: WriterEvents
      The vectors backing this writer rolled over. This means that data for the current row has been rolled over into a new vector. Offsets and indexes should be shifted based on the understanding that data for the current row now resides at the start of a new vector instead of its previous location elsewhere in an old vector.
      Specified by:
      postRollover in interface WriterEvents

    • endWrite

      public void endWrite()
      Description copied from interface: WriterEvents
      End a batch: finalize any vector values.
      Specified by:
      endWrite in interface WriterEvents

    • copy

      public void copy(ColumnReader from)
      Description copied from interface: ColumnWriter
      Copy a single value from the given reader, which must be of the same type as this writer.
      Specified by:
      copy in interface ColumnWriter
      Parameters:
      from - reader to provide the data

    • column

      public ObjectWriter column(int colIndex)
      Specified by:
      column in interface TupleWriter

    • column

      public ObjectWriter column(String colName)
      Specified by:
      column in interface TupleWriter

    • set

      public void set(int colIndex, Object value)
      Description copied from interface: TupleWriter
      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.
      Specified by:
      set in interface TupleWriter
      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

    • setObject

      public void setObject(Object value)
      Description copied from interface: ColumnWriter
      Generic technique to write data as a generic Java object. The type of the object must match the target writer. Primarily for testing.
      • Scalar: The type of the Java object must match the type of the target vector. String or byte[] can be used for Varchar vectors.
      • Array: Write the array given an array of values. The object must be a Java array. The type of the array must match the type of element in the repeated vector. That is, if the vector is a Repeated Int, provide an int[] array.
      • Tuple (map or row): The Java object must be an array of objects in which the members of the array have a 1:1 correspondence with the members of the tuple in the order defined by the writer metadata. That is, if the map is (Int, Varchar), provide a Object[] array like this: {10, "fred"}.
      • Union: Uses the Java object type to determine the type of the backing vector. Creates a vector of the required type if needed.
      Specified by:
      setObject in interface ColumnWriter
      Parameters:
      value - value to write to the vector. The Java type of the object indicates the Drill storage type

    • scalar

      public ScalarWriter scalar(int colIndex)
      Specified by:
      scalar in interface TupleWriter

    • scalar

      public ScalarWriter scalar(String colName)
      Specified by:
      scalar in interface TupleWriter

    • tuple

      public TupleWriter tuple(int colIndex)
      Specified by:
      tuple in interface TupleWriter

    • tuple

      public TupleWriter tuple(String colName)
      Specified by:
      tuple in interface TupleWriter

    • array

      public ArrayWriter array(int colIndex)
      Specified by:
      array in interface TupleWriter

    • array

      public ArrayWriter array(String colName)
      Specified by:
      array in interface TupleWriter

    • variant

      public VariantWriter variant(int colIndex)
      Specified by:
      variant in interface TupleWriter

    • variant

      public VariantWriter variant(String colName)
      Specified by:
      variant in interface TupleWriter

    • dict

      public DictWriter dict(int colIndex)
      Specified by:
      dict in interface TupleWriter

    • dict

      public DictWriter dict(String colName)
      Specified by:
      dict in interface TupleWriter

    • type

      public ObjectType type(int colIndex)
      Specified by:
      type in interface TupleWriter

    • type

      public ObjectType type(String colName)
      Specified by:
      type in interface TupleWriter

    • isProjected

      public boolean isProjected()
      Description copied from interface: ColumnWriter
      Whether this writer is projected (is backed by a materialized vector), or is unprojected (is just a dummy writer.) In most cases, clients can ignore whether the column is projected and just write to the writer. This flag handles those special cases where it is helpful to know if the column is projected or not.
      Specified by:
      isProjected in interface ColumnWriter

    • lastWriteIndex

      public int lastWriteIndex()
      Description copied from interface: WriterPosition
      Return the last write position in the vector. This may be the same as the writer index position (if the vector was written at that point), or an earlier point. In either case, this value points to the last valid value in the vector.
      Specified by:
      lastWriteIndex in interface WriterPosition
      Returns:
      index of the last valid value in the vector

    • writeIndex

      public int writeIndex()
      Description copied from interface: WriterPosition
      Current write index for the writer. This is the global array location for arrays, same as the row index for top-level columns.
      Specified by:
      writeIndex in interface WriterPosition
      Returns:
      current write index

    • bindListener

      public void bindListener(AbstractTupleWriter.TupleWriterListener listener)

    • listener

      public AbstractTupleWriter.TupleWriterListener listener()

    • bindListener

      public void bindListener(WriterEvents.ColumnWriterListener listener)
      Description copied from interface: WriterEvents
      Bind a listener to the underlying vector writer. This listener reports on vector events (overflow, growth), and so is called only when the writer is backed by a vector. The listener is ignored (and never called) for dummy (non-projected) columns. If the column is compound (such as for a nullable or repeated column, or for a map), then the writer is bound to the individual components.
      Specified by:
      bindListener in interface WriterEvents
      Parameters:
      listener - the vector event listener to bind

    • dump

      public void dump(HierarchicalFormatter format)
      Specified by:
      dump in interface WriterEvents