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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-8374) Better support of null for UDF
Date Tue, 06 Jan 2015 23:28:35 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-8374?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14266957#comment-14266957
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Jonathan Ellis commented on CASSANDRA-8374:
-------------------------------------------

bq. Defaulting to {{RETURNS NULL ON NULL INPUT}} is surprising behavior, both from a programming
languages perspective and a database perspective

I agree.  99% of the time nobody will notice, 1% of the time this will cause hours of head
scratching.

I think the two reasonable options are

# Make {{CALLED ON NULL INPUT}} the default, the way it is everywhere else ever
# Force choosing the behavior explicitly


> Better support of null for UDF
> ------------------------------
>
>                 Key: CASSANDRA-8374
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8374
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Sylvain Lebresne
>            Assignee: Robert Stupp
>             Fix For: 3.0
>
>         Attachments: 8473-1.txt, 8473-2.txt
>
>
> Currently, every function needs to deal with it's argument potentially being {{null}}.
There is very many case where that's just annoying, users should be able to define a function
like:
> {noformat}
> CREATE FUNCTION addTwo(val int) RETURNS int LANGUAGE JAVA AS 'return val + 2;'
> {noformat}
> without having this crashing as soon as a column it's applied to doesn't a value for
some rows (I'll note that this definition apparently cannot be compiled currently, which should
be looked into).  
> In fact, I think that by default methods shouldn't have to care about {{null}} values:
if the value is {{null}}, we should not call the method at all and return {{null}}. There
is still methods that may explicitely want to handle {{null}} (to return a default value for
instance), so maybe we can add an {{ALLOW NULLS}} to the creation syntax.



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