io.druid.query.filter

Interface Filter

All Known Subinterfaces:

BooleanFilter

All Known Implementing Classes:

AndFilter, BoundFilter, DimensionPredicateFilter, InFilter, JavaScriptFilter, LikeFilter, NotFilter, OrFilter, RegexFilter, SearchQueryFilter, SelectorFilter, SpatialFilter

public interface Filter

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.

Method Detail

getBitmapIndex

ImmutableBitmap getBitmapIndex(BitmapIndexSelector selector)

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

Parameters:

selector - Object used to retrieve bitmap indexes

Returns:

A bitmap indicating rows that match this filter.

See Also:

estimateSelectivity(BitmapIndexSelector)

estimateSelectivity

double estimateSelectivity(BitmapIndexSelector indexSelector)

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.

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:

getBitmapIndex(BitmapIndexSelector)

makeMatcher

ValueMatcher makeMatcher(ColumnSelectorFactory factory)

Get a ValueMatcher that applies this filter to row values.

Parameters:

factory - Object used to create ValueMatchers

Returns:

ValueMatcher that applies this filter to row values.

supportsBitmapIndex

boolean supportsBitmapIndex(BitmapIndexSelector selector)

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

Parameters:

selector - Object used to retrieve bitmap indexes

Returns:

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

supportsSelectivityEstimation

boolean supportsSelectivityEstimation(ColumnSelector columnSelector,
                                      BitmapIndexSelector indexSelector)

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.

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.