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Hive >> mail # user >> handling null argument in custom udf


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Re: handling null argument in custom udf
Right. Thanks for all the help.
It turned out that it did help to check for null in the code. No mystery.
I did try that earlier but the attempt got lost somehow.

Thanks for the advise on using GenericUDF.

cheers
S�ren

On 05/12/2012 11:10, Vivek Mishra wrote:
> The way UDF works is, you need to tell your ObjectInspector about your primitive or JavaTypes. So in your case even if value is null, you should be able to assign it as a String or any other object. Then invocation to evaluate() function should know about type of java object.
>
> -Vivek
> ________________________________________
> From: Vivek Mishra
> Sent: 05 December 2012 15:36
> To: [EMAIL PROTECTED]
> Subject: RE: handling null argument in custom udf
>
> Could you please look into and share your task log/attemptlog for complete error trace or actual error behind this?
>
> -Vivek
> ________________________________________
> From: S�ren [[EMAIL PROTECTED]]
> Sent: 04 December 2012 20:28
> To: [EMAIL PROTECTED]
> Subject: Re: handling null argument in custom udf
>
> Thanks. Did you mean I should handle null in my udf or my serde?
>
> I did try to check for null inside the code in my udf, but it fails even before it gets called.
>
> This is from when the udf fails:
> ....
> Caused by: org.apache.hadoop.hive.ql.metadata.HiveException: Unable to execute method public org.apache.hadoop.io.Text com.company.hive.myfun.evaluate(java.lang.Object,java.lang.Object)
> on objectcom.company.hive.myfun@1412332 of class com.company.hive.myfun with arguments {0:java.lang.Object, null} of size 2
>
> It looks like there is a null, or is this error message misleading?
>
>
> On 04/12/2012 15:43, Edward Capriolo wrote:
> There is no null argument. You should handle the null case in your code.
>
> If (arga == null)
>
> Or optionally you could use a generic udf but a regular one should handle what you are doing.
>
> On Tuesday, December 4, 2012, S�ren <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
>> Hi Hive community
>>
>> I have a custom udf, say myfun, written in Java which I utilize like this
>>
>> select myfun(col_a, col_b) from mytable where ....etc
>>
>> col_b is a string type and sometimes it is null.
>>
>> When that happens, my query crashes with
>> ---------------
>> java.lang.RuntimeException: org.apache.hadoop.hive.ql.metadata.HiveException: Hive Runtime Error while processing row
>> {"col_a":"val","col_b":null}
>> ...
>> Caused by: org.apache.hadoop.hive.ql.metadata.HiveException: Unable to execute method public org.apache.hadoop.io.Text
>> ---------------
>>
>> public final class myfun extends UDF {
>>          public Text evaluate(final Text argA, final Text argB) {
>>
>> I'm unsure how this should be fixed in a proper way. Is the framework looking for an overload of evaluate that would comply with the null argument?
>>
>> I need to say that the table is declared using my own json serde reading from S3. I'm not processing nulls in my serde in any special way because Hive seems to handle null in the right way when not passed to my own UDF.
>>
>> Are there anyone out there with ideas or experiences on this issue?
>>
>> thanks in advance
>> S�ren
>>
>>
>
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NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB