Hari Sankar Sivarama Subramaniyan created HIVE-12084:
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Summary: Hive queries with ORDER BY and large LIMIT fails with
OutOfMemoryError Java heap space
Key: HIVE-12084
URL: https://issues.apache.org/jira/browse/HIVE-12084
Project: Hive
Issue Type: Bug
Reporter: Hari Sankar Sivarama Subramaniyan
Assignee: Hari Sankar Sivarama Subramaniyan
STEPS TO REPRODUCE:
{code}
CREATE TABLE `sample_07` ( `code` string , `description` string , `total_emp`
int , `salary` int ) ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t' STORED AS
TextFile;
load data local inpath 'sample_07.csv' into table sample_07;
set hive.limit.pushdown.memory.usage=0.9999;
select * from sample_07 order by salary LIMIT 999999999;
{code}
This will result in
{code}
Caused by: java.lang.OutOfMemoryError: Java heap space
at org.apache.hadoop.hive.ql.exec.TopNHash.initialize(TopNHash.java:113)
at
org.apache.hadoop.hive.ql.exec.ReduceSinkOperator.initializeOp(ReduceSinkOperator.java:234)
at
org.apache.hadoop.hive.ql.exec.vector.VectorReduceSinkOperator.initializeOp(VectorReduceSinkOperator.java:68)
at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:385)
at org.apache.hadoop.hive.ql.exec.Operator.initialize(Operator.java:469)
at
org.apache.hadoop.hive.ql.exec.Operator.initializeChildren(Operator.java:425)
{code}
The basic issue lies with top n optimization. We need a limit for the top n
optimization. Ideally we would detect that the allocated bytes will be bigger
than the "limit.pushdown.memory.usage" without trying to alloc it.
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