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https://issues.apache.org/jira/browse/SPARK-13380?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Reynold Xin resolved SPARK-13380.
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Resolution: Fixed
Assignee: Xiao Li
Fix Version/s: 2.0.0
> Document Rand(seed) and Randn(seed) Return Indeterministic Results When Data
> Partitions are not fixed
> -----------------------------------------------------------------------------------------------------
>
> Key: SPARK-13380
> URL: https://issues.apache.org/jira/browse/SPARK-13380
> Project: Spark
> Issue Type: Documentation
> Components: SQL
> Affects Versions: 2.0.0
> Reporter: Xiao Li
> Assignee: Xiao Li
> Priority: Minor
> Fix For: 2.0.0
>
>
> rand and randn functions with a seed argument are commonly used. Based on the
> common sense, the results of rand and randn should be deterministic if the
> seed parameter value is provided. For example, in MS SQL Server, it also has
> a function rand. Regarding the parameter seed, the description is like: Seed
> is an integer expression (tinyint, smallint, or int) that gives the seed
> value. If seed is not specified, the SQL Server Database Engine assigns a
> seed value at random. For a specified seed value, the result returned is
> always the same.
> Update: the current implementation is unable to generate deterministic
> results when the partitions are not fixed. This PR documents this issue in
> the function descriptions.
> @jkbradley hit an issue and provided an example in the following JIRA:
> https://issues.apache.org/jira/browse/SPARK-13333
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