[
https://issues.apache.org/jira/browse/HIVE-164?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Zheng Shao updated HIVE-164:
----------------------------
Attachment: HIVE-164.6.patch
Simplified the interface for GenericUDF. I guess it's easy to write a
GenericUDF without too much knowledge of Hive (the developer will still need to
know about ObjectInspector).
{code}
@UDFType(deterministic=true)
public abstract class GenericUDF {
/**
* A Defered Object allows us to do lazy-evaluation
* and short-circuiting.
* GenericUDF use DeferedObject to pass arguments.
*/
public static interface DeferredObject {
public Object get() throws HiveException;
};
/**
* The constructor
*/
public GenericUDF() {
}
/**
* Initialize this GenericUDF. This will be called once and only once per
* GenericUDF instance.
*
* @param arguments The ObjectInspector for the arguments
* @throws UDFArgumentTypeException
* Thrown when arguments have wrong types
* @return The ObjectInspector for the return value
*/
public abstract ObjectInspector initialize(ObjectInspector[] arguments)
throws UDFArgumentTypeException;
/**
* Evaluate the GenericUDF with the arguments.
* @param arguments The arguments as DeferedObject, use DeferedObject.get()
to
* get the actual argument Object. The Objects can be
inspected
* by the ObjectInspectors passed in the initialize call.
* @return The
*/
public abstract Object evaluate(DeferredObject[] arguments) throws
HiveException;
/**
* Get the String to be displayed in explain.
*/
public abstract String getDisplayString(String[] children);
}
{code}
> Support CASE statement using GenericUDF
> ---------------------------------------
>
> Key: HIVE-164
> URL: https://issues.apache.org/jira/browse/HIVE-164
> Project: Hadoop Hive
> Issue Type: New Feature
> Components: Query Processor
> Reporter: Zheng Shao
> Assignee: Zheng Shao
> Attachments: HIVE-164.4.patch, HIVE-164.5.patch, HIVE-164.6.patch
>
>
> See http://dev.mysql.com/doc/refman/5.0/en/control-flow-functions.html for
> details.
> Syntax:
> {code}
> CASE value WHEN [compare_value] THEN result [WHEN [compare_value] THEN result
> ...] [<ELSE result] END
> CASE WHEN [condition] THEN result [WHEN [condition] THEN result ...] [ELSE
> result] END
> {code}
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
