io.druid.query.filter

Interface ValueMatcherFactory

public interface ValueMatcherFactory

A ValueMatcherFactory is an object associated with a collection of rows (e.g., an IncrementalIndexStorageAdapter) that generates ValueMatchers for filtering on the associated collection of rows. A ValueMatcher is an object that decides whether a row value matches a value or predicate associated with the ValueMatcher. The ValueMatcher is expected to track the current row to be matched with a stateful object (e.g., a ColumnSelectorFactory). The ValueMatcher has no responsibility for moving the current "row pointer", this is handled outside of the ValueMatcher. The ValueMatcherFactory/ValueMatcher classes are used for filtering rows during column scans.

Method Summary

Modifier and Type	Method and Description
ValueMatcher	makeValueMatcher(String dimension, Comparable value) Create a ValueMatcher that compares row values to the provided value.
ValueMatcher	makeValueMatcher(String dimension, DruidPredicateFactory predicateFactory) Create a ValueMatcher that applies a predicate to row values.

Method Detail

makeValueMatcher

ValueMatcher makeValueMatcher(String dimension,
                              Comparable value)

Create a ValueMatcher that compares row values to the provided value. An implementation of this method should be able to handle dimensions of various types.

Parameters:

dimension - The dimension to filter.

value - The value to match against.

Returns:

An object that matches row values on the provided value.

makeValueMatcher

ValueMatcher makeValueMatcher(String dimension,
                              DruidPredicateFactory predicateFactory)

Create a ValueMatcher that applies a predicate to row values. The caller provides a predicate factory that can create a predicate for each value type supported by Druid. See DruidPredicateFactory for more information. When creating the ValueMatcher, the ValueMatcherFactory implementation should decide what type of predicate to create from the predicate factory based on the ValueType of the specified dimension.

Parameters:

dimension - The dimension to filter.

predicateFactory - Predicate factory

Returns:

An object that applies a predicate to row values