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From ayan guha <>
Subject Re: More instances = slower Spark job
Date Thu, 28 Sep 2017 13:45:57 GMT

Can you kindly explain how Spark uses parallelism for bigger (say 1GB) text
file? Does it use InputFormat do create multiple splits and creates 1
partition per split? Also, in case of S3 or NFS, how does the input split
work? I understand for HDFS files are already pre-split so Spark can use
dfs.blocksize to determine partitions. But how does it work other than HDFS?

On Thu, Sep 28, 2017 at 11:26 PM, Daniel Siegmann <> wrote:

> no matter what you do and how many nodes you start, in case you have a
>> single text file, it will not use parallelism.
> This is not true, unless the file is small or is gzipped (gzipped files
> cannot be split).

Best Regards,
Ayan Guha

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