Package io.deephaven.engine.table.impl.sources.aggregate

Class BaseAggregateSlicedColumnSource<VECTOR_TYPE extends Vector<VECTOR_TYPE>,COMPONENT_TYPE>

java.lang.Object

io.deephaven.engine.table.impl.AbstractColumnSource<VECTOR_TYPE>

io.deephaven.engine.table.impl.sources.aggregate.BaseAggregateSlicedColumnSource<VECTOR_TYPE,COMPONENT_TYPE>

All Implemented Interfaces:

ChunkSource<Values>, ChunkSource.WithPrev<Values>, ColumnSource<VECTOR_TYPE>, ElementSource<VECTOR_TYPE>, FillContextMaker, GetContextMaker, ColumnSourceGetDefaults.ForObject<VECTOR_TYPE>, DefaultChunkSource<Values>, DefaultChunkSource.WithPrev<Values>, MutableColumnSource<VECTOR_TYPE>, MutableColumnSourceGetDefaults.ForObject<VECTOR_TYPE>, AggregateColumnSource<VECTOR_TYPE,COMPONENT_TYPE>, UngroupableColumnSource, Releasable, TupleExporter<VECTOR_TYPE>, TupleSource<VECTOR_TYPE>

Direct Known Subclasses:

SlicedByteAggregateColumnSource, SlicedCharAggregateColumnSource, SlicedDoubleAggregateColumnSource, SlicedFloatAggregateColumnSource, SlicedIntAggregateColumnSource, SlicedLongAggregateColumnSource, SlicedObjectAggregateColumnSource, SlicedShortAggregateColumnSource

public abstract class BaseAggregateSlicedColumnSource<VECTOR_TYPE extends Vector<VECTOR_TYPE>,COMPONENT_TYPE>
extends AbstractColumnSource<VECTOR_TYPE>
implements AggregateColumnSource<VECTOR_TYPE,COMPONENT_TYPE>

Base ColumnSource implementation for sliced rowset aggregation result columns.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static final class	BaseAggregateSlicedColumnSource.AggregateSlicedFillContext

Nested classes/interfaces inherited from class io.deephaven.engine.table.impl.AbstractColumnSource

AbstractColumnSource.DefaultedImmutable<DATA_TYPE>, AbstractColumnSource.DefaultedMutable<DATA_TYPE>

Nested classes/interfaces inherited from interface io.deephaven.engine.table.impl.sources.aggregate.AggregateColumnSource

AggregateColumnSource.FactoryHelper

Nested classes/interfaces inherited from interface io.deephaven.engine.table.ChunkSource

ChunkSource.FillContext, ChunkSource.GetContext, ChunkSource.WithPrev<ATTR extends Any>

Nested classes/interfaces inherited from interface io.deephaven.engine.table.impl.DefaultChunkSource

DefaultChunkSource.SupportsContiguousGet<ATTR extends Any>, DefaultChunkSource.WithPrev<ATTR extends Any>

Nested classes/interfaces inherited from interface io.deephaven.engine.table.TupleExporter

TupleExporter.ExportElementFunction<TUPLE_TYPE>

Field Summary

Fields

Modifier and Type	Field	Description
protected final ColumnSource<COMPONENT_TYPE>	aggregatedSource
protected final ColumnSource<COMPONENT_TYPE>	aggregatedSourcePrev
protected final long	endOffset
protected final @Nullable ColumnSource<Long>	endSource
protected final ColumnSource<? extends RowSet>	groupRowSetSource
protected final long	startOffset
protected final @Nullable ColumnSource<Long>	startSource

Fields inherited from class io.deephaven.engine.table.impl.AbstractColumnSource

componentType, type, updateGraph, USE_RANGES_AVERAGE_RUN_LENGTH

Fields inherited from interface io.deephaven.engine.table.ChunkSource

DEFAULT_FILL_INSTANCE, ZERO_LENGTH_CHUNK_SOURCE_ARRAY

Fields inherited from interface io.deephaven.engine.table.ChunkSource.WithPrev

ZERO_LENGTH_CHUNK_SOURCE_WITH_PREV_ARRAY

Fields inherited from interface io.deephaven.engine.table.ColumnSource

ZERO_LENGTH_COLUMN_SOURCE_ARRAY

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	BaseAggregateSlicedColumnSource(@NotNull Class<VECTOR_TYPE> vectorType, @NotNull ColumnSource<COMPONENT_TYPE> aggregatedSource, @NotNull ColumnSource<? extends RowSet> groupRowSetSource, long startOffset, long endOffset)
protected	BaseAggregateSlicedColumnSource(@NotNull Class<VECTOR_TYPE> vectorType, @NotNull ColumnSource<COMPONENT_TYPE> aggregatedSource, @NotNull ColumnSource<? extends RowSet> groupRowSetSource, @NotNull ColumnSource<Long> startSource, @NotNull ColumnSource<Long> endSource)

Method Summary

Modifier and Type	Method	Description
protected RowSet	getPrevGroupRowSet(long groupIndexKey)
final Object	getUngrouped(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one Object element out of the vector.
final Boolean	getUngroupedBoolean(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one Boolean element out of the vector.
final byte	getUngroupedByte(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one byte element out of the vector.
final char	getUngroupedChar(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one char element out of the vector.
final double	getUngroupedDouble(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one double element out of the vector.
final float	getUngroupedFloat(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one float element out of the vector.
final int	getUngroupedInt(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one int element out of the vector.
final long	getUngroupedLong(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one long element out of the vector.
final Object	getUngroupedPrev(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one Object element out of the vector as of end of the previous update cycle.
final Boolean	getUngroupedPrevBoolean(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one Boolean element out of the vector as of end of the previous update cycle.
final byte	getUngroupedPrevByte(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one byte element out of the vector as of end of the previous update cycle.
final char	getUngroupedPrevChar(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one char element out of the vector as of end of the previous update cycle.
final double	getUngroupedPrevDouble(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one double element out of the vector as of end of the previous update cycle.
final float	getUngroupedPrevFloat(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one float element out of the vector as of end of the previous update cycle.
final int	getUngroupedPrevInt(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one int element out of the vector as of end of the previous update cycle.
final long	getUngroupedPrevLong(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one long element out of the vector as of end of the previous update cycle.
final short	getUngroupedPrevShort(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one short element out of the vector as of end of the previous update cycle.
final long	getUngroupedPrevSize(long groupRowKey)
final short	getUngroupedShort(long groupRowKey, int offsetInGroup)	Reach into a grouped column source and pull one short element out of the vector.
long	getUngroupedSize(long groupRowKey)
boolean	isImmutable()	Determine if this column source is immutable, meaning that the values at a given row key never change.
boolean	isStateless()	Most column sources will return the same value for a given row without respect to the order that the rows are read.
final boolean	isUngroupable()	Does this particular ColumnSource support ungrouping?
final ChunkSource.FillContext	makeFillContext(int chunkCapacity, SharedContext sharedContext)	Allocate a new ChunkSource.FillContext for filling chunks from this FillContextMaker, typically a ChunkSource.
final void	startTrackingPrevValues()	ColumnSource implementations that track previous values have the option to not actually start tracking previous values until this method is called.
final UngroupedColumnSource<COMPONENT_TYPE>	ungrouped()

Methods inherited from class io.deephaven.engine.table.impl.AbstractColumnSource

allowsReinterpret, defaultFillChunk, defaultFillPrevChunk, doReinterpret, fillChunk, fillPrevChunk, getComponentType, getPrevSource, getType, match, reinterpret

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.deephaven.engine.table.ChunkSource

fillChunk

Methods inherited from interface io.deephaven.engine.table.ChunkSource.WithPrev

fillPrevChunk

Methods inherited from interface io.deephaven.engine.table.ColumnSource

allowsReinterpret, cast, cast, cast, cast, createPreviousTuple, createTuple, createTupleFromValues, exportAllTo, exportElement, exportElement, getChunkType, getComponentType, getPrevSource, getType, match, reinterpret, releaseCachedResources, tupleLength

Methods inherited from interface io.deephaven.engine.table.impl.ColumnSourceGetDefaults.ForObject

getBoolean, getByte, getChar, getDouble, getFloat, getInt, getLong, getShort

Methods inherited from interface io.deephaven.engine.table.impl.DefaultChunkSource

getChunk, getChunk, getChunkByFilling, makeGetContext

Methods inherited from interface io.deephaven.engine.table.impl.DefaultChunkSource.WithPrev

getPrevChunk, getPrevChunk, getPrevChunkByFilling

Methods inherited from interface io.deephaven.engine.table.ElementSource

get, getPrev

Methods inherited from interface io.deephaven.engine.table.FillContextMaker

makeFillContext

Methods inherited from interface io.deephaven.engine.table.GetContextMaker

makeGetContext

Methods inherited from interface io.deephaven.engine.table.impl.MutableColumnSourceGetDefaults.ForObject

getPrevBoolean, getPrevByte, getPrevChar, getPrevDouble, getPrevFloat, getPrevInt, getPrevLong, getPrevShort

Methods inherited from interface io.deephaven.engine.table.TupleExporter

exportAllReinterpretedTo, exportAllReinterpretedTo, exportAllTo, exportElementReinterpreted

Methods inherited from interface io.deephaven.engine.table.TupleSource

createTupleFromReinterpretedValues

Field Details

aggregatedSource

protected final ColumnSource<COMPONENT_TYPE> aggregatedSource

aggregatedSourcePrev

protected final ColumnSource<COMPONENT_TYPE> aggregatedSourcePrev

groupRowSetSource

protected final ColumnSource<? extends RowSet> groupRowSetSource

startSource

@Nullable
protected final @Nullable ColumnSource<Long> startSource

endSource

@Nullable
protected final @Nullable ColumnSource<Long> endSource

startOffset

protected final long startOffset

endOffset

protected final long endOffset

Constructor Details

BaseAggregateSlicedColumnSource

protected BaseAggregateSlicedColumnSource(@NotNull
 @NotNull Class<VECTOR_TYPE> vectorType,
 @NotNull
 @NotNull ColumnSource<COMPONENT_TYPE> aggregatedSource,
 @NotNull
 @NotNull ColumnSource<? extends RowSet> groupRowSetSource,
 @NotNull
 @NotNull ColumnSource<Long> startSource,
 @NotNull
 @NotNull ColumnSource<Long> endSource)

BaseAggregateSlicedColumnSource

protected BaseAggregateSlicedColumnSource(@NotNull
 @NotNull Class<VECTOR_TYPE> vectorType,
 @NotNull
 @NotNull ColumnSource<COMPONENT_TYPE> aggregatedSource,
 @NotNull
 @NotNull ColumnSource<? extends RowSet> groupRowSetSource,
 long startOffset,
 long endOffset)

Method Details

ungrouped

public final UngroupedColumnSource<COMPONENT_TYPE> ungrouped()

Specified by:

ungrouped in interface AggregateColumnSource<VECTOR_TYPE extends Vector<VECTOR_TYPE>,COMPONENT_TYPE>

startTrackingPrevValues

public final void startTrackingPrevValues()

Description copied from interface: ColumnSource

ColumnSource implementations that track previous values have the option to not actually start tracking previous values until this method is called. This is an option, not an obligation: some simple ColumnSource implementations (like TSingleValueSource for various T) always track previous values; other implementations (like PrevColumnSource) never do; some (like TArrayColumnSource) only start tracking once this method is called. An immutable column source can not have distinct prev values; therefore it is implemented as a no-op.

Specified by:

startTrackingPrevValues in interface ColumnSource<VECTOR_TYPE extends Vector<VECTOR_TYPE>>

makeFillContext

public final ChunkSource.FillContext makeFillContext(int chunkCapacity,
 SharedContext sharedContext)

Description copied from interface: FillContextMaker

Allocate a new ChunkSource.FillContext for filling chunks from this FillContextMaker, typically a ChunkSource.

Specified by:

makeFillContext in interface DefaultChunkSource<VECTOR_TYPE extends Vector<VECTOR_TYPE>>

Specified by:

makeFillContext in interface FillContextMaker

Parameters:

chunkCapacity - The maximum size of any WritableChunk that will be filled with this context

sharedContext - Shared store of intermediate results.

Returns:

A context for use with fill operations

isUngroupable

public final boolean isUngroupable()

Description copied from interface: UngroupableColumnSource

Does this particular ColumnSource support ungrouping?

Specified by:

isUngroupable in interface UngroupableColumnSource

Returns:

true if you can call the getUngrouped family of methods and get a valid answer

getUngroupedSize

public long getUngroupedSize(long groupRowKey)

Specified by:

getUngroupedSize in interface UngroupableColumnSource

getUngroupedPrevSize

public final long getUngroupedPrevSize(long groupRowKey)

Specified by:

getUngroupedPrevSize in interface UngroupableColumnSource

getPrevGroupRowSet

protected RowSet getPrevGroupRowSet(long groupIndexKey)

getUngrouped

public final Object getUngrouped(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one Object element out of the vector.

Specified by:

getUngrouped in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((ObjectVector)columnSource.get(groupRowKey)).get(offsetInGroup)

getUngroupedPrev

public final Object getUngroupedPrev(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one Object element out of the vector as of end of the previous update cycle.

Specified by:

getUngroupedPrev in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((ObjectVector)columnSource.getPrev(groupRowKey)).get(offsetInGroup)

getUngroupedBoolean

public final Boolean getUngroupedBoolean(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one Boolean element out of the vector.

Specified by:

getUngroupedBoolean in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((ObjectVector)columnSource.get(groupRowKey)).get(offsetInGroup)

getUngroupedPrevBoolean

public final Boolean getUngroupedPrevBoolean(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one Boolean element out of the vector as of end of the previous update cycle.

Specified by:

getUngroupedPrevBoolean in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((ObjectVector)columnSource.getPrev(groupRowKey)).get(offsetInGroup)

getUngroupedDouble

public final double getUngroupedDouble(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one double element out of the vector.

Specified by:

getUngroupedDouble in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((DoubleVector)columnSource.get(groupRowKey)).get(offsetInGroup)

getUngroupedPrevDouble

public final double getUngroupedPrevDouble(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one double element out of the vector as of end of the previous update cycle.

Specified by:

getUngroupedPrevDouble in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((DoubleVector)columnSource.getPrev(groupRowKey)).get(offsetInGroup)

getUngroupedFloat

public final float getUngroupedFloat(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one float element out of the vector.

Specified by:

getUngroupedFloat in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((FloatVector)columnSource.get(groupRowKey)).get(offsetInGroup)

getUngroupedPrevFloat

public final float getUngroupedPrevFloat(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one float element out of the vector as of end of the previous update cycle.

Specified by:

getUngroupedPrevFloat in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((FloatVector)columnSource.getPrev(groupRowKey)).get(offsetInGroup)

getUngroupedByte

public final byte getUngroupedByte(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one byte element out of the vector.

Specified by:

getUngroupedByte in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((ByteVector)columnSource.get(groupRowKey)).get(offsetInGroup)

getUngroupedPrevByte

public final byte getUngroupedPrevByte(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one byte element out of the vector as of end of the previous update cycle.

Specified by:

getUngroupedPrevByte in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((ByteVector)columnSource.getPrev(groupRowKey)).get(offsetInGroup)

getUngroupedChar

public final char getUngroupedChar(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one char element out of the vector.

Specified by:

getUngroupedChar in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((CharVector)columnSource.get(groupRowKey)).get(offsetInGroup)

getUngroupedPrevChar

public final char getUngroupedPrevChar(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one char element out of the vector as of end of the previous update cycle.

Specified by:

getUngroupedPrevChar in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((CharVector)columnSource.getPrev(groupRowKey)).get(offsetInGroup)

getUngroupedShort

public final short getUngroupedShort(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one short element out of the vector.

Specified by:

getUngroupedShort in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((ShortVector)columnSource.get(groupRowKey)).get(offsetInGroup)

getUngroupedPrevShort

public final short getUngroupedPrevShort(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one short element out of the vector as of end of the previous update cycle.

Specified by:

getUngroupedPrevShort in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((ShortVector)columnSource.getPrev(groupRowKey)).get(offsetInGroup)

getUngroupedInt

public final int getUngroupedInt(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one int element out of the vector.

Specified by:

getUngroupedInt in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((IntVector)columnSource.get(groupRowKey)).get(offsetInGroup)

getUngroupedPrevInt

public final int getUngroupedPrevInt(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one int element out of the vector as of end of the previous update cycle.

Specified by:

getUngroupedPrevInt in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((IntVector)columnSource.getPrev(groupRowKey)).get(offsetInGroup)

getUngroupedLong

public final long getUngroupedLong(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one long element out of the vector.

Specified by:

getUngroupedLong in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((LongVector)columnSource.getLong(groupRowKey)).get(offsetInGroup)

getUngroupedPrevLong

public final long getUngroupedPrevLong(long groupRowKey,
 int offsetInGroup)

Description copied from interface: UngroupableColumnSource

Reach into a grouped column source and pull one long element out of the vector as of end of the previous update cycle.

Specified by:

getUngroupedPrevLong in interface UngroupableColumnSource

Parameters:

groupRowKey - The vector's row key in the grouped column source

offsetInGroup - Positional offset within the vector at groupRowKey

Returns:

Equivalent to ((LongVector)columnSource.getPrev(groupRowKey)).get(offsetInGroup)

isStateless

public boolean isStateless()

Description copied from interface: ColumnSource

Most column sources will return the same value for a given row without respect to the order that the rows are read. Those columns sources are considered "stateless" and should return true. Some column sources, however may be dependent on evaluation order. For example, a formula that updates a Map must be evaluated from the first row to the last row. A column source that has the potential to depend on the order of evaluation must return false.

Specified by:

isStateless in interface ColumnSource<VECTOR_TYPE extends Vector<VECTOR_TYPE>>

Returns:

true if this is a stateless column source

isImmutable

public boolean isImmutable()

Description copied from interface: ColumnSource

Determine if this column source is immutable, meaning that the values at a given row key never change.

Specified by:

isImmutable in interface ColumnSource<VECTOR_TYPE extends Vector<VECTOR_TYPE>>

Specified by:

isImmutable in interface MutableColumnSource<VECTOR_TYPE extends Vector<VECTOR_TYPE>>

Returns:

true if the values at a given row key of the column source never change, false otherwise