org.apache.druid.query.filter

Interface Filter

All Known Subinterfaces:

BooleanFilter

All Known Implementing Classes:

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

@SubclassesMustOverrideEqualsAndHashCode
public interface Filter

Method Summary

Modifier and Type	Method and Description
default boolean	canVectorizeMatcher(ColumnInspector inspector) Returns true if this filter can produce a vectorized matcher from its "makeVectorMatcher" method.
default 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.
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.
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, ColumnIndexSelector indexSelector) Indicates whether this filter supports selectivity estimation.

Method Detail

getBitmapColumnIndex

@Nullable
BitmapColumnIndex getBitmapColumnIndex(ColumnIndexSelector selector)

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), or examine details about the index prior to computing it, via BitmapColumnIndex.getIndexCapabilities().

Parameters:

selector - Object used to create BitmapColumnIndex

Returns:

BitmapColumnIndex that can build ImmutableBitmap of matched row numbers

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.

estimateSelectivity

default double estimateSelectivity(ColumnIndexSelector 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 indexes

Returns:

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

See Also:

getBitmapColumnIndex(ColumnIndexSelector)

supportsSelectivityEstimation

boolean supportsSelectivityEstimation(ColumnSelector columnSelector,
                                      ColumnIndexSelector 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(ColumnInspector inspector)

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

Parameters:

inspector - Supplies type information for the selectors this filter will match against

getRequiredColumns

Set<String> getRequiredColumns()

Set of columns used by a filter.

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