Package org.apache.druid.segment.filter

Class ColumnComparisonFilter

java.lang.Object

org.apache.druid.segment.filter.ColumnComparisonFilter

All Implemented Interfaces:

Filter

public class ColumnComparisonFilter
extends Object
implements Filter

Compares values between columns, first converting them all to strings. This filter behaves like "not distinct from", e.g. given columns x and y, the SQL equivalent would be "x is not distinct from y" (and so ignores includeUnknown).

Constructor Summary

Constructors

Constructor	Description
ColumnComparisonFilter(List<DimensionSpec> dimensions)

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object o)
double	estimateSelectivity(ColumnIndexSelector indexSelector)	Estimate selectivity of this filter.
BitmapColumnIndex	getBitmapColumnIndex(ColumnIndexSelector selector)	Returns a BitmapColumnIndex if this filter supports using a bitmap index for filtering for the given input ColumnIndexSelector.
Set<String>	getRequiredColumns()	Set of columns used by a filter.
int	hashCode()
ValueMatcher	makeMatcher(ColumnSelectorFactory factory)	Get a ValueMatcher that applies this filter to row values.
static ValueMatcher	makeValueMatcher(List<Supplier<String[]>> 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	supportsSelectivityEstimation(ColumnSelector columnSelector, ColumnIndexSelector indexSelector)	Indicates whether this filter supports selectivity estimation.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.druid.query.filter.Filter

canVectorizeMatcher, makeVectorMatcher, rewriteRequiredColumns, supportsRequiredColumnRewrite

Constructor Detail

ColumnComparisonFilter

public ColumnComparisonFilter(List<DimensionSpec> dimensions)

Method Detail

getBitmapColumnIndex

@Nullable
public BitmapColumnIndex getBitmapColumnIndex(ColumnIndexSelector selector)

Description copied from interface: Filter

Returns a BitmapColumnIndex if this filter supports using a bitmap index for filtering for the given input ColumnIndexSelector. The BitmapColumnIndex can be used to compute into a bitmap indicating rows that match this filter result BitmapColumnIndex.computeBitmapResult(BitmapResultFactory, boolean), or examine details about the index prior to computing it, via BitmapColumnIndex.getIndexCapabilities().

Specified by:

getBitmapColumnIndex in interface Filter

Parameters:

selector - Object used to create BitmapColumnIndex

Returns:

BitmapColumnIndex that can build ImmutableBitmap of matched row numbers

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(List<Supplier<String[]>> 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.

supportsSelectivityEstimation

public boolean supportsSelectivityEstimation(ColumnSelector columnSelector,
                                             ColumnIndexSelector 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.

getRequiredColumns

public Set<String> getRequiredColumns()

Description copied from interface: Filter

Set of columns used by a filter.

Specified by:

getRequiredColumns in interface Filter

estimateSelectivity

public double estimateSelectivity(ColumnIndexSelector 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 indexes

Returns:

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

See Also:

Filter.getBitmapColumnIndex(ColumnIndexSelector)

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object