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From Fabian Hueske <fhue...@apache.org>
Subject Re: Flink Mongodb
Date Tue, 04 Nov 2014 15:37:14 GMT
Local split assignment preferably assigns input split to workers that can
locally read the data of an input split.
For example, HDFS stores file chunks (blocks) distributed over the cluster
and gives access to these chunks to every worker via network transfer.
However, if a chunk is read from a process that runs on the same node as
the chunk is stored, the read operation directly accesses the local file
system without going over the network. Hence, it is essential to assign
input splits based on the locality of their data if you want to have
reasonably performance. We call this local split assignment. This is a
general concept of all data parallel systems including Hadoop, Spark, and
Flink.

This issue is not related to serializability of input formats.
I assume that the wrapped MongoIF is also not capable of local split
assignment.

Am Dienstag, 4. November 2014 schrieb Flavio Pompermaier :

> What do you mean for  "might lack support for local split assignment"? You
> mean that InputFormat is not serializable? This instead is not true for
> Mongodb?
>
> On Tue, Nov 4, 2014 at 10:00 AM, Fabian Hueske <fhueske@apache.org> wrote:
>
>> There's a page about Hadoop Compatibility that shows how to use the
>> wrapper.
>>
>> The HBase format should work as well, but might lack support for local
>> split assignment. In that case performance would suffer a lot.
>>
>> Am Dienstag, 4. November 2014 schrieb Flavio Pompermaier :
>>
>>> Should I start from
>>> http://flink.incubator.apache.org/docs/0.7-incubating/example_connectors.html
>>> ? Is it ok?
>>> Thus, in principle, also the TableInputFormat of HBase could be used in
>>> a similar way..isn't it?
>>>
>>> On Tue, Nov 4, 2014 at 9:42 AM, Fabian Hueske <fhueske@apache.org>
>>> wrote:
>>>
>>>> Hi,
>>>>
>>>> the blog post uses Flinks wrapper for Hadoop InputFormats.
>>>> This has been ported to the new API and is described in the
>>>> documentation.
>>>>
>>>> So you just need to take Mongos Hadoop IF and plug it into the new IF
>>>> wrapper. :-)
>>>>
>>>> Fabian
>>>>
>>>> Am Dienstag, 4. November 2014 schrieb Flavio Pompermaier :
>>>>
>>>> Hi to all,
>>>>>
>>>>> I saw this post
>>>>> https://flink.incubator.apache.org/news/2014/01/28/querying_mongodb.html
>>>>> but it use the old APIs (HadoopDataSource instead of DataSource).
>>>>> How can I use Mongodb with the new Flink APIs?
>>>>>
>>>>> Best,
>>>>> Flavio
>>>>>
>>>>
>>>

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