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https://issues.apache.org/jira/browse/CASSANDRA-11938?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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C. Scott Andreas updated CASSANDRA-11938:
-----------------------------------------
Component/s: Documentation and Website
CQL
> Clarify difference between cast and cast in CQL
> -----------------------------------------------
>
> Key: CASSANDRA-11938
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11938
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL, Documentation and Website
> Reporter: Sylvain Lebresne
> Priority: Major
>
> We have, in CQL, 2 notons of casts:
> * {{(int)?}}
> * (CAST c as int)
> which is pretty confusing, especially in the code where both are called
> "cast".
> Turns out both have somewhat different behavior (whether that justifies
> having the 2 is debatable, but it's the way it is now):
> * {{(int)?}} is really just a type hint for the type system. It will never
> "convert" value. In particular, doing {{(int)x}} where {{x}} is explicitly a
> {{bigint}} is invalid because {{bigint}} is 8 bytes while {{int}} is only 4
> bytes. Meaning that this type of "cast" is useful when the type system needs
> help,for instance when you have a bind marker and the type system can't infer
> it's type from context.
> * {{(CAST c as int)}} is actually about conversions and you can do it even if
> {{c}} is a {{bigint}}.
> Now, even if both notions are useful, we can't call both "casts" or that's
> really confusing. As we can't really rename the 2nd form since it explicitly
> use {{CAST}} in the syntax, I suggest calling the first form a "type hint"
> (which is kind of what it is).
> That ticket is about reflecting that naming change in the code as well as
> where appropriate in the doc (we can use the occasion to improve the doc on
> the difference while at it).
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