Package org.apache.druid.segment.filter

Class TrueFilter

java.lang.Object

org.apache.druid.segment.filter.TrueFilter

All Implemented Interfaces:

Filter

public class TrueFilter
extends Object
implements Filter

Method Summary

Modifier and Type	Method	Description
boolean	canVectorizeMatcher(ColumnInspector inspector)	Returns true if this filter can produce a vectorized matcher from its "makeVectorMatcher" method.
boolean	equals(Object obj)
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()
static TrueFilter	instance()
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	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.
String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

instance

public static TrueFilter instance()

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.

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.

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.

canVectorizeMatcher

public boolean canVectorizeMatcher(ColumnInspector inspector)

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

Parameters:

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

getRequiredColumns

public Set<String> getRequiredColumns()

Description copied from interface: Filter

Set of columns used by a filter.

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

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)

toString

public String toString()

Overrides:

toString in class Object

hashCode

public final int hashCode()

Overrides:

hashCode in class Object

equals

public final boolean equals(Object obj)

Overrides:

equals in class Object