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https://issues.apache.org/jira/browse/SPARK-19035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15794221#comment-15794221
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Wenchen Fan commented on SPARK-19035:
-------------------------------------
This is because the `rand()` in GROUP BY and in `SELECT` are different, the
default seed for `rand()` is not fixed. Maybe we should make the default seed
for `rand()` fixed. To workaround this issue, you can use subquery:
{code}
SELECT b, count(1) FROM (SELECT CASE WHEN a=1 THEN 1 ELSE concat(a,cast(rand()
as string)) END b) t group by b
{code}
> rand() function in case when cause failed
> -----------------------------------------
>
> Key: SPARK-19035
> URL: https://issues.apache.org/jira/browse/SPARK-19035
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.0.0, 2.0.1, 2.0.2
> Reporter: Feng Yuan
>
> *In this case:*
> select
> case when a=1 then 1 else concat(a,cast(rand() as
> string)) end b,count(1)
> from
> yuanfeng1_a
> group by
> case when a=1 then 1 else concat(a,cast(rand() as
> string)) end;
> *Throw error:*
> Error in query: expression 'yuanfeng1_a.`a`' is neither present in the group
> by, nor is it an aggregate function. Add to group by or wrap in first() (or
> first_value) if you don't care which value you get.;;
> Aggregate [CASE WHEN (a#2075 = 1) THEN cast(1 as string) ELSE
> concat(cast(a#2075 as string), cast(rand(519367429988179997) as string))
> END], [CASE WHEN (a#2075 = 1) THEN cast(1 as string) ELSE concat(cast(a#2075
> as string), cast(rand(8090243936131101651) as string)) END AS b#2074]
> +- MetastoreRelation default, yuanfeng1_a
> select case when a=1 then 1 else rand() end b,count(1) from yuanfeng1_a group
> by case when a=1 then rand() end also output this
> *Notice*:
> If replace rand() as 1,it work.
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