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https://issues.apache.org/jira/browse/CASSANDRA-7813?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14158543#comment-14158543
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Tyler Hobbs commented on CASSANDRA-7813:
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Okay, it sounds like consensus is on using keyspaces instead of namespaces.

bq.  But then we should change the syntax slightly from '::' to '.' as the 
separator.

Agreed.

bq. Regarding search order, I'd prefer to search 'system' before current 
keyspace. If it's clearly documented that system is searched first, users can 
prevent name clashes when new native functions are added.

I also agree.  Users can always be safe and explicitly specify the keyspace 
when executing UDFs.

> Decide how to deal with conflict between native and user-defined functions
> --------------------------------------------------------------------------
>
>                 Key: CASSANDRA-7813
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7813
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Sylvain Lebresne
>            Assignee: Benjamin Lerer
>              Labels: cql
>             Fix For: 3.0
>
>
> We have a bunch of native/hardcoded functions (now(), dateOf(), ...) and in 
> 3.0, user will be able to define new functions. Now, there is a very high 
> change that we will provide more native functions over-time (to be clear, I'm 
> not particularly for adding native functions for allthethings just because we 
> can, but it's clear that we should ultimately provide more than what we 
> have). Which begs the question: how do we want to deal with the problem of 
> adding a native function potentially breaking a previously defined 
> user-defined function?
> A priori I see the following options (maybe there is more?):
> # don't do anything specific, hoping that it won't happen often and consider 
> it a user problem if it does.
> # reserve a big number of names that we're hoping will cover all future need.
> # make native function and user-defined function syntactically distinct so it 
> cannot happen.
> I'm not a huge fan of solution 1). Solution 2) is actually what we did for 
> UDT but I think it's somewhat less practical here: there is so much types 
> that it makes sense to provide natively and so it wasn't too hard to come up 
> with a reasonably small list of types name to reserve just in case. This 
> feels a lot harder for functions to me.
> Which leaves solution 3). Since we already have the concept of namespaces for 
> functions, a simple idea would be to force user function to have namespace. 
> We could even allow that namespace to be empty as long as we force the 
> namespace separator (so we'd allow {{bar::foo}} and {{::foo}} for user 
> functions, but *not* {{foo}} which would be reserved for native function).



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