org.apache.druid.segment.join

Class Joinables

java.lang.Object

org.apache.druid.segment.join.Joinables

public class Joinables
extends Object

Utility methods for working with Joinable related classes.

Constructor Summary

Constructors

Constructor and Description
Joinables()

Method Summary

Modifier and Type	Method and Description
static void	checkPrefixesForDuplicatesAndShadowing(List<String> prefixes) Check if any prefixes in the provided list duplicate or shadow each other.
static Function<SegmentReference,SegmentReference>	createSegmentMapFn(List<PreJoinableClause> clauses, JoinableFactory joinableFactory, AtomicLong cpuTimeAccumulator, Query<?> query) Creates a Function that maps base segments to HashJoinSegment if needed (i.e.
static boolean	isPrefixedBy(String columnName, String prefix)
static String	validatePrefix(String prefix) Checks that "prefix" is a valid prefix for a join clause (see JoinableClause.getPrefix()) and, if so, returns it.

Methods inherited from class java.lang.Object

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

Constructor Detail

Joinables

public Joinables()

Method Detail

validatePrefix

public static String validatePrefix(@Nullable
                                    String prefix)

Checks that "prefix" is a valid prefix for a join clause (see JoinableClause.getPrefix()) and, if so, returns it. Otherwise, throws an exception.

isPrefixedBy

public static boolean isPrefixedBy(String columnName,
                                   String prefix)

createSegmentMapFn

public static Function<SegmentReference,SegmentReference> createSegmentMapFn(List<PreJoinableClause> clauses,
                                                                             JoinableFactory joinableFactory,
                                                                             AtomicLong cpuTimeAccumulator,
                                                                             Query<?> query)

Creates a Function that maps base segments to HashJoinSegment if needed (i.e. if the number of join clauses is > 0). If mapping is not needed, this method will return Function.identity().

Parameters:

clauses - Pre-joinable clauses

joinableFactory - Factory for joinables

cpuTimeAccumulator - An accumulator that we will add CPU nanos to; this is part of the function to encourage callers to remember to track metrics on CPU time required for creation of Joinables

query - The query that will be run on the mapped segments. Usually this should be analysis.getBaseQuery().orElse(query), where "analysis" is a DataSourceAnalysis and "query" is the original query from the end user.

checkPrefixesForDuplicatesAndShadowing

public static void checkPrefixesForDuplicatesAndShadowing(List<String> prefixes)

Check if any prefixes in the provided list duplicate or shadow each other.

Parameters:

prefixes - A mutable list containing the prefixes to check. This list will be sorted by descending string length.