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From "Robert Stupp (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-7813) Decide how to deal with conflict between native and user-defined functions
Date Mon, 01 Sep 2014 12:29:21 GMT


Robert Stupp commented on CASSANDRA-7813:

I'm fine with "binding" UDFs to keyspaces instead of artificial namespaces.
But then we should change the syntax slightly from '::' to '.' as the separator.
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'm -1 on introducing something like "search path" because IMO it tends to make things more
complicated and error-prone.

> Decide how to deal with conflict between native and user-defined functions
> --------------------------------------------------------------------------
>                 Key: CASSANDRA-7813
>                 URL:
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Sylvain Lebresne
>              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
> 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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