Package org.apache.druid.segment

Class UnnestDimensionCursor

java.lang.Object

org.apache.druid.segment.UnnestDimensionCursor

All Implemented Interfaces:

Cursor

public class UnnestDimensionCursor
extends Object
implements Cursor

The cursor to help unnest MVDs with dictionary encoding. Consider a segment has 2 rows ['a', 'b', 'c'] ['d', 'c']

Considering dictionary encoding, these are represented as

'a' -> 0 'b' -> 1 'c' -> 2 'd' -> 3

The baseCursor points to the row of IndexedInts [0, 1, 2] while the unnestCursor with each call of advance() moves over individual elements.

advance() -> 0 -> 'a' advance() -> 1 -> 'b' advance() -> 2 -> 'c' advance() -> 3 -> 'd' (advances base cursor first) advance() -> 2 -> 'c'

Total 5 advance calls above

The index reference points to the index of each row that the unnest cursor is accessing The indexedInts for each row are held in the indexedIntsForCurrentRow object

The needInitialization flag sets up the initial values of indexedIntsForCurrentRow at the beginning of the segment

Constructor Summary

Constructors

Constructor	Description
UnnestDimensionCursor(Cursor cursor, ColumnSelectorFactory baseColumnSelectorFactory, VirtualColumn unnestColumn, String outputColumnName)

Method Summary

Modifier and Type	Method	Description
void	advance()
void	advanceUninterruptibly()
ColumnSelectorFactory	getColumnSelectorFactory()
org.joda.time.DateTime	getTime()
boolean	isDone()
boolean	isDoneOrInterrupted()
void	reset()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UnnestDimensionCursor

public UnnestDimensionCursor(Cursor cursor,
                             ColumnSelectorFactory baseColumnSelectorFactory,
                             VirtualColumn unnestColumn,
                             String outputColumnName)

Method Detail

getColumnSelectorFactory

public ColumnSelectorFactory getColumnSelectorFactory()

Specified by:

getColumnSelectorFactory in interface Cursor

getTime

public org.joda.time.DateTime getTime()

Specified by:

getTime in interface Cursor

advance

public void advance()

Specified by:

advance in interface Cursor

advanceUninterruptibly

public void advanceUninterruptibly()

Specified by:

advanceUninterruptibly in interface Cursor

isDone

public boolean isDone()

Specified by:

isDone in interface Cursor

isDoneOrInterrupted

public boolean isDoneOrInterrupted()

Specified by:

isDoneOrInterrupted in interface Cursor

reset

public void reset()

Specified by:

reset in interface Cursor