io.druid.segment.filter

Class SelectorFilter

java.lang.Object

io.druid.segment.filter.SelectorFilter

All Implemented Interfaces:

Filter

public class SelectorFilter
extends Object
implements Filter

Constructor Summary

Constructors

Constructor and Description
SelectorFilter(String dimension, String value)

Method Summary

Modifier and Type	Method and Description
double	estimateSelectivity(BitmapIndexSelector indexSelector) Estimate selectivity of this filter.
ImmutableBitmap	getBitmapIndex(BitmapIndexSelector selector) Get a bitmap index, indicating rows that match this filter.
ValueMatcher	makeMatcher(ColumnSelectorFactory factory) Get a ValueMatcher that applies this filter to row values.
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.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

SelectorFilter

public SelectorFilter(String dimension,
                      String value)

Method Detail

getBitmapIndex

public ImmutableBitmap getBitmapIndex(BitmapIndexSelector selector)

Description copied from interface: Filter

Get a bitmap index, indicating rows that match this filter.

Specified by:

getBitmapIndex 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.

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)

toString

public String toString()

Overrides:

toString in class Object