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

Interface WriterEvents

All Superinterfaces:
WriterPosition
All Known Subinterfaces:
OffsetVectorWriter, UnionShim
All Known Implementing Classes:
AbstractArrayWriter, AbstractArrayWriter.BaseArrayWriter, AbstractFixedWidthWriter, AbstractFixedWidthWriter.BaseFixedWidthWriter, AbstractFixedWidthWriter.BaseIntWriter, AbstractScalarWriterImpl, AbstractTupleWriter, BaseScalarWriter, BaseVarWidthWriter, BitColumnWriter, ColumnAccessors.BigIntColumnWriter, ColumnAccessors.DateColumnWriter, ColumnAccessors.Decimal18ColumnWriter, ColumnAccessors.Decimal28SparseColumnWriter, ColumnAccessors.Decimal38SparseColumnWriter, ColumnAccessors.Decimal9ColumnWriter, ColumnAccessors.Float4ColumnWriter, ColumnAccessors.Float8ColumnWriter, ColumnAccessors.IntColumnWriter, ColumnAccessors.IntervalColumnWriter, ColumnAccessors.IntervalDayColumnWriter, ColumnAccessors.IntervalYearColumnWriter, ColumnAccessors.SmallIntColumnWriter, ColumnAccessors.TimeColumnWriter, ColumnAccessors.TimeStampColumnWriter, ColumnAccessors.TinyIntColumnWriter, ColumnAccessors.UInt1ColumnWriter, ColumnAccessors.UInt2ColumnWriter, ColumnAccessors.UInt4ColumnWriter, ColumnAccessors.UInt8ColumnWriter, ColumnAccessors.Var16CharColumnWriter, ColumnAccessors.VarBinaryColumnWriter, ColumnAccessors.VarCharColumnWriter, ColumnAccessors.VarDecimalColumnWriter, DictEntryWriter, DummyArrayWriter, DummyArrayWriter.DummyOffsetVectorWriter, DummyDictWriter, DummyScalarWriter, EmptyListShim, ListWriterImpl, MapWriter, MapWriter.ArrayMapWriter, MapWriter.DummyArrayMapWriter, MapWriter.DummyMapWriter, MapWriter.SingleMapWriter, NullableScalarWriter, ObjectArrayWriter, ObjectDictWriter, OffsetVectorWriterImpl, RepeatedListWriter, RowSetLoaderImpl, RowSetWriterImpl, ScalarArrayWriter, SimpleListShim, UnionShim.AbstractUnionShim, UnionVectorShim, UnionWriterImpl
public interface WriterEvents extends WriterPosition
Internal interface used to control the behavior of writers. Consumers of writers never use this method; it is instead used by the code that implements writers.

Most methods here represents events in a state machine. The top-level writer provides a set of public methods which trigger one or more of these internal events. The events draw some fine distinctions between top-level values and those nested within arrays. See each kind of writer for the details.

The events also ensure symmetry between top-level and nested tuples, especially those nested within an array. That is, an event cannot change meaning depending on whether the tuple is top-level or nested within an array. Instead, the order of calls, or selectively making or not making calls, can change.

  • Method Details

    • bindIndex

      void bindIndex(ColumnWriterIndex index)
      Bind the writer to a writer index.
      Parameters:
      index - the writer index (top level or nested for arrays)

    • bindListener

      void bindListener(WriterEvents.ColumnWriterListener listener)
      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.
      Parameters:
      listener - the vector event listener to bind

    • startWrite

      void startWrite()
      Start a write (batch) operation. Performs any vector initialization required at the start of a batch (especially for offset vectors.)

    • startRow

      void startRow()
      Start a new row. To be called only when a row is not active. To restart a row, call restartRow() instead.

    • endArrayValue

      void endArrayValue()
      End a value. Similar to 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.

    • restartRow

      void restartRow()
      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.

    • saveRow

      void saveRow()
      Saves a row. Commits offset vector locations and advances each to the next position. Can be called only when a row is active.

    • endWrite

      void endWrite()
      End a batch: finalize any vector values.

    • preRollover

      void preRollover()
      The vectors backing this vector are about to roll over. Finish the current batch up to, but not including, the current row.

    • postRollover

      void postRollover()
      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.

    • dump

      void dump(HierarchicalFormatter format)