Package io.deephaven.engine.table.impl.join

Class ChangedKeyRows

java.lang.Object

io.deephaven.engine.table.impl.join.ChangedKeyRows

public class ChangedKeyRows
extends Object

Splits the modified rows of an update into those whose key value changed and those whose key value did not, by comparing the previous key values (read at the pre-shift row keys) with the current key values (read at the post-shift row keys). A join only needs to move the rows whose key value changed between hash slots; the rest keep their slot and cost no hash lookups.

The previous key values of the changed rows are handed to an optional probe as each chunk is processed, so a hash table keyed by the previous values can drop those rows without reading the previous values a second time.

Constructor Summary

Constructors

Constructor	Description
ChangedKeyRows(ChunkType[] chunkTypes)

Method Summary

Modifier and Type	Method	Description
void	findChanged(ColumnSource<?>[] keySources, RowSet modifiedPreShift, RowSet modifiedPostShift, @Nullable RowSetBuilderSequential changedPreShift, RowSetBuilderSequential changedPostShift, TypedHasherUtil.ProbeHandler previousKeyProbe)	Find the modified rows whose key value changed.

Methods inherited from class java.lang.Object

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

Constructor Details

ChangedKeyRows

public ChangedKeyRows(ChunkType[] chunkTypes)

Method Details

findChanged

public void findChanged(ColumnSource<?>[] keySources,
 RowSet modifiedPreShift,
 RowSet modifiedPostShift,
 @Nullable
 @Nullable RowSetBuilderSequential changedPreShift,
 RowSetBuilderSequential changedPostShift,
 @Nullable
 TypedHasherUtil.ProbeHandler previousKeyProbe)

Find the modified rows whose key value changed.

Parameters:

keySources - the key sources, one per key column, read for both previous and current values

modifiedPreShift - the modified rows in pre-shift key space, aligned positionally with modifiedPostShift

modifiedPostShift - the modified rows in post-shift key space

changedPreShift - if not null, output, ascending, receives the pre-shift keys of the rows whose key value changed, aligned with changedPostShift

changedPostShift - output, ascending, receives the post-shift keys of the rows whose key value changed

previousKeyProbe - if not null, called once per chunk with the changed rows' pre-shift row keys and their previous key values