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From Alan Gates <ga...@apache.org>
Subject Re: External Table with unclosed orc files.
Date Wed, 15 Apr 2015 17:18:18 GMT
So it was in the map reduce job itself? Then the best information would
be the logs from the MR job, so we can see what it's doing (or perhaps
not doing).

Alan.

Grant Overby (groverby) wrote:
> It wasn’t reliably reproducible for us. If we killed the compaction
> job in yarn and manually triggered compaction for the same partition,
> it would succeed. We would see this about 1 time every 2 days / 200
> partitions. There weren’t any errors logged that we noticed. The job
> was simply sitting there making no progress.
>
> I’m not using acid tables currently, but I’ll likely give it another
> go. What information should I capture to help with this issue?
>
>
>
>
>
> From: Alan Gates <gates@apache.org <mailto:gates@apache.org>>
> Reply-To: "user@hive.apache.org <mailto:user@hive.apache.org>"
> <user@hive.apache.org <mailto:user@hive.apache.org>>,
> "gates@apache.org <mailto:gates@apache.org>" <gates@apache.org
> <mailto:gates@apache.org>>
> Date: Wednesday, April 15, 2015 at 4:07 AM
> To: "user@hive.apache.org <mailto:user@hive.apache.org>"
> <user@hive.apache.org <mailto:user@hive.apache.org>>
> Subject: Re: External Table with unclosed orc files.
>
>
>
> Grant Overby (groverby) wrote:
>> Thanks for the link to the hive streaming bolt. We rolled our own bolt
>> many moons ago to utilize hive streaming. We’ve tried it against 0.13 and
>> 0.14 . Acid tables have been a real pain for us. We don’t believe they are
>> production ready. At least in our use cases, Tez crashes for assorted
>> reasons or only assigns 1 mapper to the partition. Having delta files and
>> no base files borks mapper assignments.  Files containing flush in their
>> name are left scattered about, borking queries. Latency is higher with
>> streaming than writing to an orc file in hdfs, forcing obscene quantities
>> of buckets and orc files smaller than any reasonable orc stripe / hdfs
>> block size. The compactor hangs seemingly at random for no reason we’ve
>> been able to discern.
> The issues with flush files borking queries has been resolved in Hive
> 1.0. I haven't seen any issues with the compactor hanging at random.
> Could you expand on what parts hung? If you have a reproducible case
> it would be great to file a JIRA so we can fix it.
>
> Alan.
>> An orc file without a footer is junk data (or, at least, the last stripe
>> is junk data). I suppose my question should have been 'what will the hive
>> query do when it encounters this? Skip the stripe / file? Error out the
>> query? Something else?’
>>
>>
>>
>>
>> Grant Overby
>> Software Engineer
>> Cisco.com <http://www.cisco.com/>groverby@cisco.com
>> Mobile: 865 724 4910
>>
>>
>>
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>>
>>
>> On 4/14/15, 4:23 PM, "Gopal Vijayaraghavan" <gopalv@apache.org> wrote:
>>
>>>> What will Hive do if querying an external table containing orc files
>>>> that are still being written to?
>>> Doing that directly won¹t work at all. Because ORC files are only readable
>>> after the Footer is written out, which won¹t be for any open files.
>>>
>>>> I won¹t be able to test these scenarios till tomorrow and would like to
>>>> have some idea of what to expect this afternoon.
>>> If I remember correctly, your previous question was about writing ORC from
>>> Storm.
>>>
>>> If you¹re on a recent version of Storm, I¹d advise you to look at
>>> storm-hive/ 
>>>
>>> https://github.com/apache/storm/tree/master/external/storm-hive
>>>
>>>
>>> Or alternatively, there¹s a ³hortonworks trucking demo² which does a
>>> partition insert instead.
>>>
>>> Cheers,
>>> Gopal
>>>
>>>

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