Merging small files throws RuntimeException when hive.mergejob.maponly=false
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Key: HIVE-2869
URL: https://issues.apache.org/jira/browse/HIVE-2869
Project: Hive
Issue Type: Bug
Components: Query Processor
Affects Versions: 0.8.0
Environment: CentOS release 5.5 (Final)
Reporter: Shrijeet Paliwal
Attachments: data_to_reproduce.tar.gz
Hive Version: Hive 0.8 (last commit SHA
b581a6192b8d4c544092679d05f45b2e50d42b45 )
Hadoop version : chd3u0
Trying to use the hive merge small file feature by setting all the necessary
params.
Have disabled use of CombineHiveInputFormat since my input is compressed text.
{noformat}
hive> set mapred.min.split.size.per.node=1000000000;
hive> set mapred.min.split.size.per.rack=1000000000;
hive> set mapred.max.split.size=1000000000;
hive> set hive.merge.size.per.task=1000000000;
hive> set hive.merge.smallfiles.avgsize=1000000000;
hive> set hive.merge.size.smallfiles.avgsize=1000000000;
hive> set hive.merge.mapfiles=true;
hive> set hive.merge.mapredfiles=true;
hive> set hive.mergejob.maponly=false;
{noformat}
The plan decides to launch two MR jobs but after first job succeeds I get runt
time error
"java.lang.RuntimeException: Plan invalid, Reason: Reducers == 0 but reduce
operator specified"
*How to reproduce :*
* Creare tables as follows :
{code}
--create input table
create table tmp_notmerged (
id int,
name string
)
ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t'
STORED AS TEXTFILE;
--create o/p table
create table tmp_merged (
id int
)
STORED AS TEXTFILE;
{code}
* Load data into tmp_notmerged (find files attached in with this jira)
* set knobs and fire hive query
{code}
set hive.merge.mapfiles=true;
set hive.mergejob.maponly=false;
insert overwrite table tmp_merged select id from tmp_notmerged;
{code}
* You should see error "java.lang.RuntimeException: Plan invalid, Reason:
Reducers == 0 but reduce operator specified"
*Proposed fix :*
Patch is here : https://gist.github.com/2025303
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