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From "Prasanth Jayachandran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-17280) Data loss in CONCATENATE ORC created by Spark
Date Tue, 29 Aug 2017 17:59:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-17280?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16145785#comment-16145785
] 

Prasanth Jayachandran commented on HIVE-17280:
----------------------------------------------

Do you happen to know the filenames generated by spark? 
Hive has some assumptions around filenames when moving the files from staging to final target
directory. Recently encountered similar issue (HIVE-17403) which could be related to this
as well.

> Data loss in CONCATENATE ORC created by Spark
> ---------------------------------------------
>
>                 Key: HIVE-17280
>                 URL: https://issues.apache.org/jira/browse/HIVE-17280
>             Project: Hive
>          Issue Type: Bug
>          Components: Hive, Spark
>    Affects Versions: 1.2.1
>         Environment: Spark 1.6.3
>            Reporter: Marco Gaido
>            Priority: Critical
>
> Hive concatenation causes data loss if the ORC files in the table were written by Spark.
> Here are the steps to reproduce the problem:
>  - create a table;
> {code:java}
> hive
> hive> create table aa (a string, b int) stored as orc;
> {code}
>  - insert 2 rows using Spark;
> {code:java}
> spark-shell
> scala> case class AA(a:String, b:Int)
> scala> val df = sc.parallelize(Array(AA("b",2),AA("c",3) )).toDF
> scala> df.write.insertInto("aa")
> {code}
>  - change table schema;
> {code:java}
> hive
> hive> alter table aa add columns(aa string, bb int);
> {code}
>  - insert other 2 rows with Spark
> {code:java}
> spark-shell
> scala> case class BB(a:String, b:Int, aa:String, bb:Int)
> scala> val df = sc.parallelize(Array(BB("b",2,"b",2),BB("c",3,"c",3) )).toDF
> scala> df.write.insertInto("aa")
> {code}
>  - at this point, running a select statement with Hive returns correctly *4 rows* in
the table; then run the concatenation
> {code:java}
> hive
> hive> alter table aa concatenate;
> {code}
> At this point, a select returns only *3 rows, ie. a row is missing*.



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