io.druid.query

Class ChainedExecutionQueryRunner<T>

java.lang.Object

io.druid.query.ChainedExecutionQueryRunner<T>

All Implemented Interfaces:

QueryRunner<T>

public class ChainedExecutionQueryRunner<T>
extends Object
implements QueryRunner<T>

A QueryRunner that combines a list of other QueryRunners and executes them in parallel on an executor.

When using this, it is important to make sure that the list of QueryRunners provided is fully flattened. If, for example, you were to pass a list of a Chained QueryRunner (A) and a non-chained QueryRunner (B). Imagine A has 2 QueryRunner chained together (Aa and Ab), the fact that the Queryables are run in parallel on an executor would mean that the Queryables are actually processed in the order

A -> B -> Aa -> Ab

That is, the two sub queryables for A would run *after* B is run, effectively meaning that the results for B must be fully cached in memory before the results for Aa and Ab are computed.

Constructor Summary

Constructors

Constructor and Description
ChainedExecutionQueryRunner(ExecutorService exec, com.google.common.collect.Ordering<T> ordering, QueryWatcher queryWatcher, Iterable<QueryRunner<T>> queryables)
ChainedExecutionQueryRunner(ExecutorService exec, com.google.common.collect.Ordering<T> ordering, QueryWatcher queryWatcher, QueryRunner<T>... queryables)

Method Summary

Methods

Modifier and Type	Method and Description
com.metamx.common.guava.Sequence<T>	run(Query<T> query, Map<String,Object> responseContext)

Methods inherited from class java.lang.Object

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

Constructor Detail

ChainedExecutionQueryRunner

public ChainedExecutionQueryRunner(ExecutorService exec,
                           com.google.common.collect.Ordering<T> ordering,
                           QueryWatcher queryWatcher,
                           QueryRunner<T>... queryables)

ChainedExecutionQueryRunner

public ChainedExecutionQueryRunner(ExecutorService exec,
                           com.google.common.collect.Ordering<T> ordering,
                           QueryWatcher queryWatcher,
                           Iterable<QueryRunner<T>> queryables)

Method Detail

run

public com.metamx.common.guava.Sequence<T> run(Query<T> query,
                                      Map<String,Object> responseContext)

Specified by:

run in interface QueryRunner<T>