You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues@spark.apache.org by "Liang-Chi Hsieh (JIRA)" <ji...@apache.org> on 2018/06/20 14:41:00 UTC
[jira] [Comment Edited] (SPARK-24607) Distribute by rand() can lead
to data inconsistency
[ https://issues.apache.org/jira/browse/SPARK-24607?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16518206#comment-16518206 ]
Liang-Chi Hsieh edited comment on SPARK-24607 at 6/20/18 2:40 PM:
------------------------------------------------------------------
Thanks [~mgaido]!
As I check {{Rand}} expression, seems it already uses a seed, it sounds like the option 1 in the Hive ticket. So if you still use the same query plan, it should produce deterministic sequences of numbers.
Unless that the input of rows has a different order when retries, then it can be possible to produce inconsistent sequences in retries.
was (Author: viirya):
Thanks [~mgaido]!
As I check {{Rand}} expression, seems it already uses a seed, it sounds like the option 1 in the Hive ticket. So if you still use the same query plan, it should produce deterministic sequences of numbers.
> Distribute by rand() can lead to data inconsistency
> ---------------------------------------------------
>
> Key: SPARK-24607
> URL: https://issues.apache.org/jira/browse/SPARK-24607
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.2.0, 2.3.1
> Reporter: zenglinxi
> Priority: Major
>
> Noticed the following queries can give different results:
> {code:java}
> select count(*) from tbl;
> select count(*) from (select * from tbl distribute by rand()) a;{code}
> this issue was first reported by someone using kylin for building cube with hiveSQL which include distribute by rand, I think it's also an hidden serious problem in sparksql.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org