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https://issues.apache.org/jira/browse/SPARK-28086?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16894922#comment-16894922
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Dongjoon Hyun commented on SPARK-28086:
---------------------------------------
This issue is reported twice at [~DylanGuedes]'s PR
(https://github.com/apache/spark/pull/24881/files#diff-14489bae6b27814d4cde0456a7ae75c8R702)
and [~yumwang]'s PR
(https://github.com/apache/spark/pull/25163/files#diff-23a3430e0e1ff88830cbb43701da1f2cR402).
For me, PostgreSQL random function is the same with Apache Spark `rand` as a
uniform random returning 0.0 <= x < 1.0.
- https://www.postgresql.org/docs/8.2/functions-math.html
Also, Spark also accepts `order by rand()` like the following.
{code}
spark-sql> SELECT rank() OVER (ORDER BY rank() OVER (ORDER BY rand()));
1
{code}
So, let's make an alias and unblock the other issues. I'll make a PR.
> Adds `random()` sql function
> ----------------------------
>
> Key: SPARK-28086
> URL: https://issues.apache.org/jira/browse/SPARK-28086
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 3.0.0
> Reporter: Dylan Guedes
> Priority: Major
>
> Currently, Spark does not have a `random()` function. Postgres, however, does.
> For instance, this one is not valid:
> {code:sql}
> SELECT rank() OVER (ORDER BY rank() OVER (ORDER BY random()))
> {code}
> Because of the `random()` call. On the other hand, [Postgres has
> it.|https://www.postgresql.org/docs/8.2/functions-math.html]
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