Package org.apache.druid.math.expr

Class ExpressionPredicateIndexSupplier

java.lang.Object

org.apache.druid.math.expr.ExpressionPredicateIndexSupplier

All Implemented Interfaces:

ColumnIndexSupplier

public class ExpressionPredicateIndexSupplier
extends Object
implements ColumnIndexSupplier

Uses the underlying dictionary values of a column to provide DruidPredicateIndexes that apply an Expr to the values of an input column before matching with a DruidPredicateFactory. This supplier is only suitable for use on a direct column, and that column must be dictionary encoded and provides DictionaryEncodedValueIndex so that the dictionary values can be iterated and transformed with the Expr

Constructor Summary

Constructors

Constructor	Description
ExpressionPredicateIndexSupplier(Expr expr, String inputColumn, ExpressionType inputType, ColumnType outputType, DictionaryEncodedValueIndex<?> inputColumnValueIndexes)

Method Summary

Modifier and Type	Method	Description
<T> T	as(Class<T> clazz)	Try to get a column 'index' of the specified type.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ExpressionPredicateIndexSupplier

public ExpressionPredicateIndexSupplier(Expr expr,
 String inputColumn,
 ExpressionType inputType,
 ColumnType outputType,
 DictionaryEncodedValueIndex<?> inputColumnValueIndexes)

Method Details

as

@Nullable
public <T> T as(Class<T> clazz)

Description copied from interface: ColumnIndexSupplier

Try to get a column 'index' of the specified type. If the index of the desired type is not available, this method will return null. If the value is non-null, the index may be used for the eventual construction of an Offset to form the basis of a Cursor (or VectorOffset and VectorCursor) which can greatly reduce the total number of rows which need to be scanned and processed. Objects returned by this method are not thread-safe. There are several built-in index classes which can be passed as an argument to this method when used from Filter.getBitmapColumnIndex(ColumnIndexSelector). Implementors of this interface should provide as many of them as possible to participate fully in as many Filter as possible, as different filters require different index types, and may prefer some over others. Indexes for matching a row to a specific value:

Specified by:

as in interface ColumnIndexSupplier

See Also:

• NullValueIndex
• Indexes for matching a row to any of a set of values:
• ValueSetIndexes
• Indexes for matching a row to a range of values:
• LexicographicalRangeIndexes
• Indexes for matching an array element of a row to a specific value:
• Indexes for matching a row using a org.apache.druid.query.filter.DruidPredicateFactory:
• Speciality indexes:
• Low level access to implementation specific index stuff not particularly suitable for use in filtering:
• DictionaryEncodedValueIndex
• DictionaryEncodedStringValueIndex