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Hive, mail # user - Help on loading data stream to hive table.


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Re: Help on loading data stream to hive table.
Alan Gates 2014-01-07, 19:39
I am not wise enough in the ways of Storm to tell you how you should partition data across bolts.  However, there is no need in Hive for all data for a partition to be in the same file, only in the same directory.  So if each bolt creates a file for each partition and then all those files are placed in one directory and loaded into Hive it will work.

Alan.

On Jan 6, 2014, at 6:26 PM, Chen Wang <[EMAIL PROTECTED]> wrote:

> Alan,
> the problem is that the data is partitioned by epoch ten hourly, and i want all data belong to that partition to be written into one file named with that partition. How can i share the file writer across different bolt? should I instruct data within the same partition to the same bolt?
> Thanks,
> Chen
>
>
> On Fri, Jan 3, 2014 at 3:27 PM, Alan Gates <[EMAIL PROTECTED]> wrote:
> You shouldn’t need to write each record to a separate file.  Each Storm bolt should be able to write to it’s own file, appending records as it goes.  As long as you only have one writer per file this should be fine.  You can then close the files every 15 minutes (or whatever works for you) and have a separate job that creates a new partition in your Hive table with the files created by your bolts.
>
> Alan.
>
> On Jan 2, 2014, at 11:58 AM, Chen Wang <[EMAIL PROTECTED]> wrote:
>
>> Guys,
>> I am using storm to read data stream from our socket server, entry by entry, and then write them to file: one entry per file.  At some point, i need to import the data into my hive table. There are several approaches i could think of:
>> 1. directly write to hive hdfs file whenever I get the entry(from our socket server). The problem is that this could be very inefficient,  since we have huge amount of data stream, and I would not want to write to hive hdfs one by one.
>> Or
>> 2 i can write the entries to files(normal file or hdfs file) on the disk, and then have a separate job to merge those small files into big one, and then load them into hive table.
>> The problem with this is, a) how can I merge small files into big files for hive? b) what is the best file size to upload to hive?
>>
>> I am seeking advice on both approaches, and appreciate your insight.
>> Thanks,
>> Chen
>>
>
>
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