[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-5212) Alter SQLFunction contract to be more flexible

[Fred Toussi (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-5212?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=37744#action_37744 ] 

Fred Toussi commented on HHH-5212:
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Sorry for the delay. Saw your comment just today. Regarding my previous comment, I'm not saying something extra in needed  (because in practice I have never seen a case of FUNCTION_NAME and FUNCTION_NAME() doing different things).

Separate from that comment, you may want to consider the case of SQL Standard functions CURRENT_TIMESTAMP \[ \( N \) \] where the parens and argument are optional but they are used to indicate the fractional second precision. If ommitted, the precision is assumed to be 6. Similar format for LOCALTIMESTAMP, CURRENT_TIME and LOCALTIME, but the time functions have zero precision if not explicitly specified.

For this type of function, perhaps something might be added to the interface to indicate the param is actually a type precision parameter and must be a number literal.

> Alter SQLFunction contract to be more flexible
> ----------------------------------------------
>
>                 Key: HHH-5212
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5212
>             Project: Hibernate Core
>          Issue Type: Improvement
>          Components: core, query-criteria, query-hql
>            Reporter: Steve Ebersole
>
> The SQLFunction contract currently combines contextual information (render/getReturnType) and non-contextual (aka non-changing) information (hasArguments/hasParenthesesIfNoArguments).
> An example I just ran into where separating these would have been nice is in HHH-5173.  Some dialects return the argument data type when applying the AVG() function.  That is problematic for INTEGER values because the decimal portion gets dropped.  On those databases one would need to CAST() the argument to get the correct behavior.  However, again, this is only necessary based on the argument type.  If the argument type is already a non-integer the cast is uneeded.
> Proposal (as always name subject to change/suggestion):
> {code}
> interface SQLFunction {
>     public boolean hasArguments();
>     public boolean hasParenthesesIfNoArguments();
>     public RenderingContext getRenderingContext(Type columnType, SessionFactoryImplementor factory);
>     public static interface RenderingContext {
>         public Type getReturnType();
>         public String render(List args);
>     }
> }
> {code}
> I used SessionFactoryImplementor as the argument to getRenderingContext, but the current getReturnType accepts a Mapping.  Is there really ever a time when we call that method when we do not have a SessionFactory?  My usage search shows no usages of this method passing in a Configuration (which is the other Mapping implementor aside from SessionFactory).

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