org.apache.drill.exec.vector.accessor

Interface ColumnWriterIndex

All Known Implementing Classes:

AbstractArrayWriter.ArrayElementWriterIndex, NullableScalarWriter.ChildIndex, ScalarArrayWriter.ScalarElementWriterIndex

public interface ColumnWriterIndex

A Drill record batch consists of a variety of vectors, including maps and lists. Each vector is written independently. A reader may skip some values in each row if no values appear for those columns.

This index provides a single view of the "current row" or "current array index" across a set of vectors. Each writer consults this index to determine:

• The position to which to write a value.
• Whether the write position is beyond the "last write" position, which would require filling in any "missing" values.

Method Summary

Modifier and Type	Method and Description
void	nextElement() Increment the index for an array.
ColumnWriterIndex	outerIndex() If this index represents a repeat level, return the index of the next higher repeat level.
void	prevElement() Decrement the index for an array.
void	rollover() When handling overflow, the index must be reset so that the current row starts at the start of the vector.
int	rowStartIndex() Index of the first entry for the current row
int	vectorIndex() Current row or array index.

Method Detail

rowStartIndex

int rowStartIndex()

Index of the first entry for the current row

Returns:

index of the first entry for the current row

vectorIndex

int vectorIndex()

Current row or array index.

Returns:

row or array index

nextElement

void nextElement()

Increment the index for an array. For arrays, writing (or saving) one value automatically moves to the next value. Ignored for non-element indexes.

prevElement

void prevElement()

Decrement the index for an array. Used exclusively for appending bytes to a VarChar, Var16Char or VarBytes column. Assumed to be followed by another call to nextElement().

rollover

void rollover()

When handling overflow, the index must be reset so that the current row starts at the start of the vector. Relative offsets must be preserved. (That is, if the current write position for an array is four greater than the start, then that offset must now be reset to four from the start of the vector.)

outerIndex

ColumnWriterIndex outerIndex()

If this index represents a repeat level, return the index of the next higher repeat level.

Returns:

the outer repeat level index, if any