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From "Julian Hyde (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-1516) Add RANDOM built-in function
Date Sun, 14 Dec 2014 06:01:13 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-1516?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14245842#comment-14245842
] 

Julian Hyde commented on PHOENIX-1516:
--------------------------------------

RAND without arguments seems to produce a new value per invocation, whereas RAND with arguments
produces one value per row. Furthermore the latter results are repeatable if you re-run the
same statement.

{code}
mysql> select rand(), rand(), rand(1), rand(1) from t1;
+---------------------+--------------------+---------------------+---------------------+
| rand()              | rand()             | rand(1)             | rand(1)             |
+---------------------+--------------------+---------------------+---------------------+
| 0.45809529112474556 | 0.7796456048075534 | 0.40540353712197724 | 0.40540353712197724 |
|  0.5239421813971756 | 0.2807741232968626 |  0.8716141803857071 |  0.8716141803857071 |
+---------------------+--------------------+---------------------+---------------------+
2 rows in set (0.00 sec)

mysql> select rand(), rand(), rand(1), rand(1) from t1;
+--------------------+---------------------+---------------------+---------------------+
| rand()             | rand()              | rand(1)             | rand(1)             |
+--------------------+---------------------+---------------------+---------------------+
| 0.8320441030264312 | 0.31789817597521297 | 0.40540353712197724 | 0.40540353712197724 |
| 0.0933586015304165 |  0.5130985104600885 |  0.8716141803857071 |  0.8716141803857071 |
+--------------------+---------------------+---------------------+---------------------+
2 rows in set (0.00 sec)
{code}

This seems to be a good semantic to implement in Phoenix (and Calcite for that matter).

> Add RANDOM built-in function
> ----------------------------
>
>                 Key: PHOENIX-1516
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-1516
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>         Attachments: 1516.txt
>
>
> I often find it useful to generate some rows with random data.
> Here's a simple RANDOM() function that we could use for that.



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