Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
Hive, mail # user - Performance Issues in Hive with S3 and Partitions


Copy link to this message
-
Re: Performance Issues in Hive with S3 and Partitions
Edward Capriolo 2012-07-24, 15:52
Generally you can not optimize this beyond a certain point. Hadoop
tasks have startup and tear down overhead, so if your input format can
not map them into less map tasks (like combine input format does) they
performance is not going to be so hot.

On Tue, Jul 24, 2012 at 11:47 AM,  <[EMAIL PROTECTED]> wrote:
> Hi Igor,
>
>
>
> Thanks for the response. Yes I am using EMR.
>
> I will make changes and let you know if that helps.
>
>
>
> Richin
>
>
>
> From: ext Igor Tatarinov [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, July 24, 2012 12:38 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Performance Issues in Hive with S3 and Partitions
>
>
>
> Are you using EMR?
>
> Have you tried  setting
>
> Hive.optimize.s3.query=true
>
> as mentioned in
>
> http://docs.amazonwebservices.com/ElasticMapReduce/latest/DeveloperGuide/emr-hive-version-details.html
>
>
>
> I haven't tried using that option myself. I am curious if it helps in your
> scenario. The above page also mentions another fix that's supposed to help
> with partitioned tables. Optimizing queries with thousands of input files
> used to take a lot of time. But it looks like that fix is enabled by default
> now.
>
>
>
> Just in case, also check your jvm reuse option. If it's too low, performance
> will suffer. I had it set to 3 to avoid running out of memory. Using the
> default value of 20 really helps when reading lots of small files.
>
>
>
> igor
>
> decide.com
>
> On Mon, Jul 23, 2012 at 8:33 PM, <[EMAIL PROTECTED]> wrote:
>
> Hi,
>
>
>
> Sorry this is an AWS Hive Specific question.  I have two External Hive
> tables for my custom logs.
>
>
>
> 1. flat directory structure on AWS S3, no partition and files in bz2
> compressed format (few big files)
>
>
>
> 2. With 3 level of partitions on AWS S3 (lot of small uncompressed files)
>
>
>
> I noticed that my queries on the table with Partition is taking forever to
> run. The same queries run fine and finish up quickly on table with no
> partition.
>
> Am I missing something, I suspect this has something to do with the way S3
> behaves.
>
>
>
> A query example is :
>
>
>
> select id, (max(unix_timestamp(ts, "MM/dd/yyyy HH:mm")) -
> min(unix_timestamp(ts, "MM/dd/yyyy HH:mm")))/(60*60)
>
> from logs
>
> group by id;
>
>
>
> Thanks,
>
> Richin
>
>