com.basho.riak.client.api.commands.kv

Class MultiFetch

java.lang.Object

com.basho.riak.client.api.RiakCommand<MultiFetch.Response,List<Location>>

com.basho.riak.client.api.commands.kv.MultiFetch

public final class MultiFetch
extends RiakCommand<MultiFetch.Response,List<Location>>

Command used to fetch multiple values from Riak.

Riak itself does not support pipelining of requests. MutliFetch addresses this issue by using a thread to parallelize and manage a set of async fetch operations for a given set of keys.

The result of executing this command is a List of RiakFuture objects, each one representing a single fetch operation. The returned RiakFuture that contains that list completes when all the FetchValue operations contained have finished.

 MultiFetch multifetch = ...;
 MultiFetch.Response response = client.execute(multifetch);
 List<MyPojo> myResults = new ArrayList<MyPojo>();
 for (RiakFuture<FetchValue.Response, Location> f : response)
 {
     try
     {
          FetchValue.Response response = f.get();
          myResults.add(response.getValue(MyPojo.class));
     }
     catch (ExecutionException e)
     {
         // log error, etc.
     }
 }

The maximum number of concurrent requests defaults to 10. This can be changed when constructing the operation.

Be aware that because requests are being parallelized performance is also dependent on the client's underlying connection pool. If there are no connections available performance will suffer initially as connections will need to be established or worse they could time out.

Since:

2.0

Author:

Dave Rusek

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MultiFetch.Builder Used to construct a MutiFetch command.
static class	MultiFetch.Response The response from Raik for a MultiFetch command.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAX_IN_FLIGHT

Method Summary

Methods

Modifier and Type	Method and Description
protected RiakFuture<MultiFetch.Response,List<Location>>	executeAsync(RiakCluster cluster)

Methods inherited from class com.basho.riak.client.api.RiakCommand

execute

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_MAX_IN_FLIGHT

public static final int DEFAULT_MAX_IN_FLIGHT

See Also:

Constant Field Values

Method Detail

executeAsync

protected RiakFuture<MultiFetch.Response,List<Location>> executeAsync(RiakCluster cluster)

Specified by:

executeAsync in class RiakCommand<MultiFetch.Response,List<Location>>