io.druid.segment.filter

Class ColumnComparisonFilter

java.lang.Object

io.druid.segment.filter.ColumnComparisonFilter

All Implemented Interfaces:

Filter

public class ColumnComparisonFilter
extends Object
implements Filter

Constructor Summary

Constructors

Constructor and Description
ColumnComparisonFilter(List<DimensionSpec> dimensions)

Method Summary

Modifier and Type	Method and Description
double	estimateSelectivity(BitmapIndexSelector indexSelector) Estimate selectivity of this filter.
<T> T	getBitmapResult(BitmapIndexSelector selector, BitmapResultFactory<T> bitmapResultFactory) Get a (possibly wrapped) bitmap index, indicating rows that match this filter.
ValueMatcher	makeMatcher(ColumnSelectorFactory factory) Get a ValueMatcher that applies this filter to row values.
static ValueMatcher	makeValueMatcher(ValueGetter[] valueGetters)
static boolean	overlap(String[] as, String[] bs) overlap returns true when: as and bs have one or more elements in common, as and bs are both null, or as and bs are both empty.
boolean	supportsBitmapIndex(BitmapIndexSelector selector) Indicates whether this filter can return a bitmap index for filtering, based on the information provided by the input BitmapIndexSelector.
boolean	supportsSelectivityEstimation(ColumnSelector columnSelector, BitmapIndexSelector indexSelector) Indicates whether this filter supports selectivity estimation.

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.druid.query.filter.Filter

getBitmapIndex

Constructor Detail

ColumnComparisonFilter

public ColumnComparisonFilter(List<DimensionSpec> dimensions)

Method Detail

getBitmapResult

public <T> T getBitmapResult(BitmapIndexSelector selector,
                             BitmapResultFactory<T> bitmapResultFactory)

Description copied from interface: Filter

Get a (possibly wrapped) bitmap index, indicating rows that match this filter. Do not call this method unless Filter.supportsBitmapIndex(BitmapIndexSelector) returns true. Behavior in the case that Filter.supportsBitmapIndex(BitmapIndexSelector) returns false is undefined.

Specified by:

getBitmapResult in interface Filter

Parameters:

selector - Object used to retrieve bitmap indexes

Returns:

A bitmap indicating rows that match this filter.

See Also:

Filter.estimateSelectivity(BitmapIndexSelector)

makeMatcher

public ValueMatcher makeMatcher(ColumnSelectorFactory factory)

Description copied from interface: Filter

Get a ValueMatcher that applies this filter to row values.

Specified by:

makeMatcher in interface Filter

Parameters:

factory - Object used to create ValueMatchers

Returns:

ValueMatcher that applies this filter to row values.

makeValueMatcher

public static ValueMatcher makeValueMatcher(ValueGetter[] valueGetters)

overlap

public static boolean overlap(@Nullable
                              String[] as,
                              @Nullable
                              String[] bs)

overlap returns true when: as and bs have one or more elements in common, as and bs are both null, or as and bs are both empty.

supportsBitmapIndex

public boolean supportsBitmapIndex(BitmapIndexSelector selector)

Description copied from interface: Filter

Indicates whether this filter can return a bitmap index for filtering, based on the information provided by the input BitmapIndexSelector.

Specified by:

supportsBitmapIndex in interface Filter

Parameters:

selector - Object used to retrieve bitmap indexes

Returns:

true if this Filter can provide a bitmap index using the selector, false otherwise.

supportsSelectivityEstimation

public boolean supportsSelectivityEstimation(ColumnSelector columnSelector,
                                             BitmapIndexSelector indexSelector)

Description copied from interface: Filter

Indicates whether this filter supports selectivity estimation. A filter supports selectivity estimation if it supports bitmap index and the dimension which the filter evaluates does not have multi values.

Specified by:

supportsSelectivityEstimation in interface Filter

Parameters:

columnSelector - Object to check the dimension has multi values.

indexSelector - Object used to retrieve bitmap indexes

Returns:

true if this Filter supports selectivity estimation, false otherwise.

estimateSelectivity

public double estimateSelectivity(BitmapIndexSelector indexSelector)

Description copied from interface: Filter

Estimate selectivity of this filter. This method can be used for cost-based query planning like in AutoStrategy. To avoid significant performance degradation for calculating the exact cost, implementation of this method targets to achieve rapid selectivity estimation with reasonable sacrifice of the accuracy. As a result, the estimated selectivity might be different from the exact value.

Specified by:

estimateSelectivity in interface Filter

Parameters:

indexSelector - Object used to retrieve bitmap indexes

Returns:

an estimated selectivity ranging from 0 (filter selects no rows) to 1 (filter selects all rows).

See Also:

Filter.getBitmapIndex(BitmapIndexSelector)