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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4982) Hive Queries degrade when queries switch between different formats
Date Sat, 03 Dec 2016 01:33:58 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4982?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15717102#comment-15717102
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ASF GitHub Bot commented on DRILL-4982:
---------------------------------------

Github user parthchandra commented on the issue:

    https://github.com/apache/drill/pull/638
  
    LGTM too. +1


> Hive Queries degrade when queries switch between different formats
> ------------------------------------------------------------------
>
>                 Key: DRILL-4982
>                 URL: https://issues.apache.org/jira/browse/DRILL-4982
>             Project: Apache Drill
>          Issue Type: Bug
>            Reporter: Chunhui Shi
>            Assignee: Karthikeyan Manivannan
>            Priority: Critical
>
> We have seen degraded performance by doing these steps:
> 1) generate the repro data:
> python script repro.py as below:
> import string
> import random
>  
> for i in range(30000000):
>     x1 = ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(random.randrange(19,
27)))
>     x2 = ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(random.randrange(19,
27)))
>     x3 = ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(random.randrange(19,
27)))
>     x4 = ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(random.randrange(19,
27)))
>     x5 = ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(random.randrange(19,
27)))
>     x6 = ''.join(random.choice(string.ascii_uppercase + string.digits) for _ in range(random.randrange(19,
27)))
>     print "{0}".format(x1),"{0}".format(x2),"{0}".format(x3),"{0}".format(x4),"{0}".format(x5),"{0}".format(x6)
> python repro.py > repro.csv
> 2) put these files in a dfs directory e.g. '/tmp/hiveworkspace/plain'. Under hive prompt,
use the following sql command to create an external table:
> CREATE EXTERNAL TABLE `hiveworkspace`.`plain` (`id1` string, `id2` string, `id3` string,
`id4` string, `id5` string, `id6` string) ROW FORMAT SERDE 'org.apache.hadoop.hive.serde2.OpenCSVSerde'
STORED AS TEXTFILE LOCATION '/tmp/hiveworkspace/plain'
> 3) create Hive's table of ORC|PARQUET format:
> CREATE TABLE `hiveworkspace`.`plainorc` STORED AS ORC AS SELECT id1,id2,id3,id4,id5,id6
from `hiveworkspace`.`plain`;
> CREATE TABLE `hiveworkspace`.`plainparquet` STORED AS PARQUET AS SELECT id1,id2,id3,id4,id5,id6
from `hiveworkspace`.`plain`;
> 4) Query switch between these two tables, then the query time on the same table significantly
lengthened. On my setup, for ORC, it was 15sec -> 26secs. Queries on table of other formats,
after injecting a query to other formats, all have significant slow down.



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