org.apache.druid.query.filter

Interface Filter

All Known Subinterfaces:

BooleanFilter

All Known Implementing Classes:

AndFilter, BoundFilter, ColumnComparisonFilter, DimensionPredicateFilter, ExpressionFilter, FalseFilter, InFilter, JavaScriptFilter, LikeFilter, NotFilter, OrFilter, RegexFilter, SearchQueryFilter, SelectorFilter, SpatialFilter, TrueFilter

@SubclassesMustOverrideEqualsAndHashCode
public interface Filter

Method Summary

Modifier and Type	Method and Description
default boolean	canVectorizeMatcher() Returns true if this filter can produce a vectorized matcher from its "makeVectorMatcher" method.
double	estimateSelectivity(BitmapIndexSelector indexSelector) Estimate selectivity of this filter.
default ImmutableBitmap	getBitmapIndex(BitmapIndexSelector selector) Get a bitmap index, indicating rows that match this filter.
<T> T	getBitmapResult(BitmapIndexSelector selector, BitmapResultFactory<T> bitmapResultFactory) Get a (possibly wrapped) bitmap index, indicating rows that match this filter.
Set<String>	getRequiredColumns() Set of columns used by a filter.
ValueMatcher	makeMatcher(ColumnSelectorFactory factory) Get a ValueMatcher that applies this filter to row values.
default VectorValueMatcher	makeVectorMatcher(VectorColumnSelectorFactory factory) Get a VectorValueMatcher that applies this filter to row vectors.
default 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.
default 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.

Method Detail

getBitmapIndex

default ImmutableBitmap getBitmapIndex(BitmapIndexSelector selector)

Get a bitmap index, indicating rows that match this filter. Do not call this method unless supportsBitmapIndex(BitmapIndexSelector) returns true. Behavior in the case that supportsBitmapIndex(BitmapIndexSelector) returns false is undefined. This method is OK to be called, but generally should not be overridden, override getBitmapResult(org.apache.druid.query.filter.BitmapIndexSelector, org.apache.druid.query.BitmapResultFactory<T>) instead.

Parameters:

selector - Object used to retrieve bitmap indexes

Returns:

A bitmap indicating rows that match this filter.

See Also:

estimateSelectivity(BitmapIndexSelector)

getBitmapResult

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

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

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.

makeVectorMatcher

default VectorValueMatcher makeVectorMatcher(VectorColumnSelectorFactory factory)

Get a VectorValueMatcher that applies this filter to row vectors.

Parameters:

factory - Object used to create ValueMatchers

Returns:

VectorValueMatcher that applies this filter to row vectors.

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

Parameters:

selector - Object used to retrieve bitmap indexes

Returns:

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

shouldUseBitmapIndex

boolean shouldUseBitmapIndex(BitmapIndexSelector selector)

Determine if a filter *should* use a bitmap index based on information collected from the supplied BitmapIndexSelector. This method differs from supportsBitmapIndex(BitmapIndexSelector) in that the former only indicates if a bitmap index is available and getBitmapIndex(BitmapIndexSelector) may be used. If shouldUseFilter(selector) returns true, 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 getBitmapIndex(BitmapIndexSelector) will return a non-null BitmapIndexSelector, and also that all columns specified in 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).

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

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.

canVectorizeMatcher

default boolean canVectorizeMatcher()

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

getRequiredColumns

Set<String> getRequiredColumns()

Set of columns used by a filter. If 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)

supportsRequiredColumnRewrite

default 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.

rewriteRequiredColumns

default 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. For example, if I have a filter (A = hello), and I have a renaming map (A -> B), this should return the filter (B = hello)

Parameters:

columnRewrites - Column rewrite map

Returns:

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