org.apache.druid.segment.filter

Class SelectorFilter

java.lang.Object

org.apache.druid.segment.filter.SelectorFilter

All Implemented Interfaces:

Filter

public class SelectorFilter
extends Object
implements Filter

This filter is to select the rows where the dimension has the value. The value can be null. In SQL-compatible null handling mode, this filter is equivalent to dimension = value or dimension IS NULL when the value is null. In default null handling mode, this filter is equivalent to dimension = value or dimension = '' when the value is null.

Constructor Summary

Constructors

Constructor and Description
SelectorFilter(String dimension, String value)
SelectorFilter(String dimension, String value, FilterTuning filterTuning)

Method Summary

Modifier and Type	Method and Description
boolean	canVectorizeMatcher() Returns true if this filter can produce a vectorized matcher from its "makeVectorMatcher" method.
boolean	equals(Object o)
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.
String	getDimension()
Set<String>	getRequiredColumns() Set of columns used by a filter.
String	getValue()
int	hashCode()
ValueMatcher	makeMatcher(ColumnSelectorFactory factory) Get a ValueMatcher that applies this filter to row values.
VectorValueMatcher	makeVectorMatcher(VectorColumnSelectorFactory factory) Get a VectorValueMatcher that applies this filter to row vectors.
Filter	rewriteRequiredColumns(Map<String,String> columnRewrites) Return a copy of this filter that is identical to the this filter except that it operates on different columns, based on a renaming map where the key is the column to be renamed in the filter, and the value is the new column name.
boolean	shouldUseBitmapIndex(BitmapIndexSelector selector) Determine if a filter *should* use a bitmap index based on information collected from the supplied BitmapIndexSelector.
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	supportsRequiredColumnRewrite() Returns true is this filter is able to return a copy of this filter that is identical to this filter except that it operates on different columns, based on a renaming map.
boolean	supportsSelectivityEstimation(ColumnSelector columnSelector, BitmapIndexSelector indexSelector) Indicates whether this filter supports selectivity estimation.
String	toString()

Methods inherited from class java.lang.Object

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

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

getBitmapIndex

Constructor Detail

SelectorFilter

public SelectorFilter(String dimension,
                      String value)

SelectorFilter

public SelectorFilter(String dimension,
                      String value,
                      @Nullable
                      FilterTuning filterTuning)

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.

makeVectorMatcher

public VectorValueMatcher makeVectorMatcher(VectorColumnSelectorFactory factory)

Description copied from interface: Filter

Get a VectorValueMatcher that applies this filter to row vectors.

Specified by:

makeVectorMatcher in interface Filter

Parameters:

factory - Object used to create ValueMatchers

Returns:

VectorValueMatcher that applies this filter to row vectors.

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. Returning a value of true here guarantees that Filter.getBitmapIndex(BitmapIndexSelector) will return a non-null BitmapIndexSelector, and also that all columns specified in Filter.getRequiredColumns() have a bitmap index retrievable via BitmapIndexSelector.getBitmapIndex(String).

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.

shouldUseBitmapIndex

public boolean shouldUseBitmapIndex(BitmapIndexSelector selector)

Description copied from interface: Filter

Determine if a filter *should* use a bitmap index based on information collected from the supplied BitmapIndexSelector. This method differs from Filter.supportsBitmapIndex(BitmapIndexSelector) in that the former only indicates if a bitmap index is available and Filter.getBitmapIndex(BitmapIndexSelector) may be used. If shouldUseFilter(selector) returns true, Filter.supportsBitmapIndex(org.apache.druid.query.filter.BitmapIndexSelector) must also return true when called with the same selector object. Returning a value of true here guarantees that Filter.getBitmapIndex(BitmapIndexSelector) will return a non-null BitmapIndexSelector, and also that all columns specified in Filter.getRequiredColumns() have a bitmap index retrievable via BitmapIndexSelector.getBitmapIndex(String). Implementations of this methods typically consider a FilterTuning to make decisions about when to use an available index. A "standard" implementation of this is available to all Filter implementations in Filters.shouldUseBitmapIndex(Filter, BitmapIndexSelector, FilterTuning).

Specified by:

shouldUseBitmapIndex in interface Filter

Parameters:

selector - Object used to retrieve bitmap indexes and provide information about the column

Returns:

true if this Filter should 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)

canVectorizeMatcher

public boolean canVectorizeMatcher()

Description copied from interface: Filter

Returns true if this filter can produce a vectorized matcher from its "makeVectorMatcher" method.

Specified by:

canVectorizeMatcher in interface Filter

getRequiredColumns

public Set<String> getRequiredColumns()

Description copied from interface: Filter

Set of columns used by a filter. If Filter.supportsBitmapIndex(org.apache.druid.query.filter.BitmapIndexSelector) returns true, all columns returned by this method can be expected to have a bitmap index retrievable via BitmapIndexSelector.getBitmapIndex(String)

Specified by:

getRequiredColumns in interface Filter

supportsRequiredColumnRewrite

public boolean supportsRequiredColumnRewrite()

Description copied from interface: Filter

Returns true is this filter is able to return a copy of this filter that is identical to this filter except that it operates on different columns, based on a renaming map.

Specified by:

supportsRequiredColumnRewrite in interface Filter

rewriteRequiredColumns

public Filter rewriteRequiredColumns(Map<String,String> columnRewrites)

Description copied from interface: Filter

Return a copy of this filter that is identical to the this filter except that it operates on different columns, based on a renaming map where the key is the column to be renamed in the filter, and the value is the new column name. For example, if I have a filter (A = hello), and I have a renaming map (A -> B), this should return the filter (B = hello)

Specified by:

rewriteRequiredColumns in interface Filter

Parameters:

columnRewrites - Column rewrite map

Returns:

Copy of this filter that operates on new columns based on the rewrite map

toString

public String toString()

Overrides:

toString in class Object

getDimension

public String getDimension()

getValue

public String getValue()

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object