Thanks Wang. I have implemented reducer in java and trying to run with below
job. But its failing with "java.io.IOException: error=2, No such file or
directory" .
I am thinking it may be due to not able to find jar/java in path. Right?
Hive Job:
add jar /home/xxxxx/embeddedDoc.jar;
from (from xxx_aggregation_struct_type as mytable
map mytable.tag, mytable.proto_agg
using '/bin/cat' as c1,c2
cluster by c1) mo
insert overwrite table mytable2
reduce mo.c1, mo.c2
using 'java -cp .:embeddedDoc.jar com.yy.xx.mapreduce.NestedDocReduce'
as x1, x2;
Exception:
------------------------------------
at org.apache.hadoop.hive.ql.exec.mr.ExecReducer.reduce(ExecReducer.java:258)
... 7 more
Caused by: org.apache.hadoop.hive.ql.metadata.HiveException: [Error 20000]:
Unable to initialize custom script.
at
org.apache.hadoop.hive.ql.exec.ScriptOperator.processOp(ScriptOperator.java:367)
at org.apache.hadoop.hive.ql.exec.Operator.process(Operator.java:504)
at org.apache.hadoop.hive.ql.exec.Operator.forward(Operator.java:842)
at
org.apache.hadoop.hive.ql.exec.SelectOperator.processOp(SelectOperator.java:88)
at org.apache.hadoop.hive.ql.exec.Operator.process(Operator.java:504)
at org.apache.hadoop.hive.ql.exec.Operator.forward(Operator.java:842)
at
org.apache.hadoop.hive.ql.exec.ExtractOperator.processOp(ExtractOperator.java:45)
at org.apache.hadoop.hive.ql.exec.Operator.process(Operator.java:504)
at
org.apache.hadoop.hive.ql.exec.mr.ExecReducer.reduce(ExecReducer.java:249)
... 7 more
Caused by: java.io.IOException: Cannot run program "java": error=2, No such
file or directory
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)
at
org.apache.hadoop.hive.ql.exec.ScriptOperator.processOp(ScriptOperator.java:326)
... 15 more
Caused by: java.io.IOException: error=2, No such file or directory
at java.lang.UNIXProcess.forkAndExec(Native Method)
at java.lang.UNIXProcess.<init>(UNIXProcess.java:135)
at java.lang.ProcessImpl.start(ProcessImpl.java:130)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1021)
... 16 more
FAILED: Execution Error, return code 20000 from
org.apache.hadoop.hive.ql.exec.mr.MapRedTask. Unable to initialize custom
script.
Thanks,
Chandra
From: Chen Wang [mailto:[email protected]]
Sent: Tuesday, February 04, 2014 3:00 AM
To: [email protected]
Subject: Re: Hadoop streaming with insert dynamic partition generate many small
files
Chandra,
You don't necessary need java to implement the mapper/reducer. Checkout the
answer in this post:
http://stackoverflow.com/questions/6178614/custom-map-reduce-program-on-hive-whats-the-rulehow-about-input-and-output
also in my sample,
A.column1, A.column2 ==> mymapper ==> key, value, and myapper simply read from
std.in<http://std.in>, and convert to key,value.
Chen
On Mon, Feb 3, 2014 at 5:51 AM, Bogala, Chandra Reddy
<[email protected]<mailto:[email protected]>> wrote:
Hi Wang,
I am first time trying MAP & Reduce inside hive query. Is it possible to
share mymapper and myreducer code? So that I can understand how the columns
(A.column1,A.... to key, value) converted? Also can you point me to some
documents to read more about it.
Thanks,
Chandra
From: Chen Wang
[mailto:[email protected]<mailto:[email protected]>]
Sent: Monday, February 03, 2014 12:26 PM
To: [email protected]<mailto:[email protected]>
Subject: Re: Hadoop streaming with insert dynamic partition generate many small
files
it seems that hive.exec.reducers.bytes.per.reducer is still not big enough: I
added another 0, and now i only gets one file under each partition.
On Sun, Feb 2, 2014 at 10:14 PM, Chen Wang
<[email protected]<mailto:[email protected]>> wrote:
Hi,
I am using java reducer reading from a table, and then write to another one:
FROM (
FROM (
SELECT column1,...
FROM table1
WHERE ( partition > 6 and partition < 12 )
) A
MAP A.column1,A....
USING 'java -cp .my.jar mymapper.mymapper'
AS key, value
CLUSTER BY key
) map_output
INSERT OVERWRITE TABLE target_table PARTITION(partition)
REDUCE
map_output.key,
map_output.value
USING 'java -cp .:myjar.jar myreducer.myreducer'
AS column1,column2;"
Its all working fine, except that there are many (20-30) small files generated
under each partition. i am setting SET
hive.exec.reducers.bytes.per.reducer=1280,000,000; hoping to get one big enough
file under for each partition.But it does not seem to have any effect. I still
get 20-30 small files under each folder, and each file size is around 7kb.
How can I force to generate only 1 big file for one partition? Does this have
anything to do with the streaming? I recall in the past i was directly reading
from a table with UDF, and write to another table, it only generates one big
file for the target partition. Not sure why is that.
Any help appreciated.
Thanks,
Chen
