The following is a an example for a GenericUDF. I wanted to test this through a
Hive query. Basically want to pass parameters some thing like "select
ComplexUDFExample('a','b','c') from employees limit 10".
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https://github.com/rathboma/hive-extension-examples/blob/master/src/main/java/com/matthewrathbone/example/ComplexUDFExample.java
class ComplexUDFExample extends GenericUDF {
ListObjectInspector listOI;
StringObjectInspector elementOI;
@Override
public String getDisplayString(String[] arg0) {
return "arrayContainsExample()"; // this should probably be better
}
@Override
public ObjectInspector initialize(ObjectInspector[] arguments) throws
UDFArgumentException {
if (arguments.length != 2) {
throw new UDFArgumentLengthException("arrayContainsExample only takes 2
arguments: List<T>, T");
}
// 1. Check we received the right object types.
ObjectInspector a = arguments[0];
ObjectInspector b = arguments[1];
if (!(a instanceof ListObjectInspector) || !(b instanceof
StringObjectInspector)) {
throw new UDFArgumentException("first argument must be a list / array,
second argument must be a string");
}
this.listOI = (ListObjectInspector) a;
this.elementOI = (StringObjectInspector) b;
// 2. Check that the list contains strings
if(!(listOI.getListElementObjectInspector() instanceof
StringObjectInspector)) {
throw new UDFArgumentException("first argument must be a list of
strings");
}
// the return type of our function is a boolean, so we provide the correct
object inspector
return PrimitiveObjectInspectorFactory.javaBooleanObjectInspector;
}
@Override
public Object evaluate(DeferredObject[] arguments) throws HiveException {
// get the list and string from the deferred objects using the object
inspectors
List<String> list = (List<String>) this.listOI.getList(arguments[0].get());
String arg = elementOI.getPrimitiveJavaObject(arguments[1].get());
// check for nulls
if (list == null || arg == null) {
return null;
}
// see if our list contains the value we need
for(String s: list) {
if (arg.equals(s)) return new Boolean(true);
}
return new Boolean(false);
}
}
hive> select ComplexUDFExample('a','b','c') from email_list_1 limit 10;
FAILED: SemanticException [Error 10015]: Line 1:7 Arguments length mismatch
''c'': arrayContainsExample only takes 2 arguments: List<T>, T
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How to test this example in Hive query. I know I am invoking it wrong. But how
can I invoke it correctly.
My requirement is to pass a String of arrays as first argument and another
string as second argument in Hive like below.
Select col1, ComplexUDFExample( collectset(col2) , 'xyz')
from
Employees
Group By col1;
How do i do that?
Thanks in advance.
Regards,
Raj
