thanks! at first I did have a no-arg evaluate(), but somehow
select myfunction(), field1, field2 from mytable ;
spits out the same value for myfunction() for each row. so I was wondering
whether the UDF got called only 1 time, because the hive compiler sees that
the argument is void, so that
all the invocations would be "having the same value", then I tried to pass
in a param to prevent this possibility.
On Mon, Sep 30, 2013 at 1:55 PM, Tim Robertson <timrobertson...@gmail.com>wrote:
> It's been ages since I wrote one, but the differences to mine:
>
> a) I use LongWritable: public LongWritable evaluate(LongWritable startAt)
> {
> b) I have annotations on the class (but I think they are just for docs)
> @Description(name = "row_sequence",
> value = "_FUNC_() - Returns a generated row sequence number starting
> from 1")
> @UDFType(deterministic = false)
> public class UDFRowSequence extends UDF {
>
> Hope this helps!
> Tim
>
>
>
> On Mon, Sep 30, 2013 at 10:47 PM, Yang <teddyyyy...@gmail.com> wrote:
>
>> I wrote a super simple UDF, but got some errors:
>>
>> UDF:
>>
>> package yy;
>> import org.apache.hadoop.hive.ql.exec.UDF;
>> import java.util.Random;
>> import java.util.UUID;
>> import java.lang.management.*;
>>
>> public class MyUdf extends UDF {
>> static Random rand = new Random(System.currentTimeMillis() +
>> Thread.currentThread().getId()* 1000000);
>> String name = ManagementFactory.getRuntimeMXBean().getName();
>> long startValue = Long.valueOf(name.replaceAll("[^\\d]+", "")) *
>> 10000 + Thread.currentThread().getId() * 1000;
>> public long evaluate(long x ) {
>> //return (long)UUID.randomUUID().hashCode();
>> //return rand.nextLong();
>> return startValue++;
>> }
>> }
>>
>>
>>
>>
>>
>> sql script:
>>
>> CREATE TEMPORARY FUNCTION gen_uniq2 AS 'yy.MyUdf';
>> select gen_uniq2(field1), field2
>> from yy_mapping limit 10;
>>
>> field1 is bigint, field2 is int
>>
>>
>>
>>
>>
>> error:
>>
>> hive> source aa.sql;
>> Added ./MyUdf.jar to class path
>> Added resource: ./MyUdf.jar
>> OK
>> Time taken: 0.0070 seconds
>> FAILED: SemanticException [Error 10014]: Line 2:7 Wrong arguments
>> 'field1': No matching method for class yy.MyUdf with (bigint). Possible
>> choices: _FUNC_()
>>
>>
>>
>>
>>
>> so I'm declaring a UDF with arg of long, so that should work for a bigint
>> (more importantly it's complaining not long vs bigint, but bigint vs void
>> ). I tried changing both to int, same failure
>>
>>
>> thanks!
>> yang
>>
>>
>>
>
