org.apache.druid.segment.vector

Interface VectorCursor

All Superinterfaces:

AutoCloseable, Closeable, VectorSizeInspector

public interface VectorCursor
extends VectorSizeInspector, Closeable

Vectorized cursor used during query execution. VectorCursors are returned by CursorFactory.makeVectorCursor(org.apache.druid.query.filter.Filter, org.joda.time.Interval, org.apache.druid.segment.VirtualColumns, boolean, int, org.apache.druid.query.QueryMetrics<?>) and are created by QueryableIndexCursorSequenceBuilder.buildVectorized(int). Unlike the non-vectorized version, VectorCursor does not have a getTime() method. This is because we are trying to avoid creating needlessly-small vectors when the time granularity is very fine. See VectorCursorGranularizer for a helper that makes it easier for query engines to do their own time granularization. An example of how to use the methods in this class:

   try (VectorCursor cursor = adapter.makeVectorCursor(...)) {
     // ProcessorClass is some vectorized processor class.
     ProcessorClass o = makeProcessor(cursor.getColumnSelectorFactory());
     for (; !cursor.isDone(); cursor.advance()) {
       o.process();
     }
   }
 

See Also:

org.apache.druid.segment.Cursor, the non-vectorized version.

Method Summary

Modifier and Type	Method and Description
void	advance() Advances the cursor, skipping forward a number of rows equal to the current vector size.
void	close() Close the cursor and release its resources.
VectorColumnSelectorFactory	getColumnSelectorFactory() Returns a vectorized column selector factory.
boolean	isDone() Returns false if the cursor is readable, true if it has nothing left to read.
void	reset() Resets the cursor back to its original state.

Methods inherited from interface org.apache.druid.segment.vector.VectorSizeInspector

getCurrentVectorSize, getMaxVectorSize

Method Detail

getColumnSelectorFactory

VectorColumnSelectorFactory getColumnSelectorFactory()

Returns a vectorized column selector factory.

advance

void advance()

Advances the cursor, skipping forward a number of rows equal to the current vector size.

isDone

boolean isDone()

Returns false if the cursor is readable, true if it has nothing left to read.

reset

void reset()

Resets the cursor back to its original state. Useful for query engines that want to make multiple passes.

close

void close()

Close the cursor and release its resources.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable