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Sylvain Lebresne commented on CASSANDRA-8374:
---------------------------------------------
I'm not exactly sure how a default value will work in practice (especially in
the example you gave above where it's only on the first argument) so I'd much
rather left that out of this ticket (and frankly, I'd rather left it out
completely at least for now: let's be careful to not feature creep UDF before
we have even released the first version).
As for the {{ALLOW NULLS}} flag, I was initially leaning towards a single
per-function one for the conceptual simplicity (and I'm not sure very fine
grained control on this is really that useful in practice). Not a terribly
strong preference however.
> 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
>
>
> 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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