Brock Noland created HIVE-4957:
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Summary: Restrict number of bit vectors, to prevent out of Java
heap memory
Key: HIVE-4957
URL: https://issues.apache.org/jira/browse/HIVE-4957
Project: Hive
Issue Type: Bug
Affects Versions: 0.11.0
Reporter: Brock Noland
normally increase number of bit vectors will increase calculation accuracy.
Let's say
{noformat}
select compute_stats(a, 40) from test_hive;
{noformat}
generally get better accuracy than
{noformat}
select compute_stats(a, 16) from test_hive;
{noformat}
But larger number of bit vectors also cause query run slower. When number of
bit vectors over 50, it won't help to increase accuracy anymore. But it still
increase memory usage, and crash Hive if number if too huge. Current Hive
doesn't prevent user use ridiculous large number of bit vectors in
'compute_stats' query.
One example
{noformat}
select compute_stats(a, 999999999) from column_eight_types;
{noformat}
crashes Hive.
{noformat}
2012-12-20 23:21:52,247 Stage-1 map = 0%, reduce = 0%
2012-12-20 23:22:11,315 Stage-1 map = 100%, reduce = 0%, Cumulative CPU 0.29
sec
MapReduce Total cumulative CPU time: 290 msec
Ended Job = job_1354923204155_0777 with errors
Error during job, obtaining debugging information...
Job Tracking URL:
http://cs-10-20-81-171.cloud.cloudera.com:8088/proxy/application_1354923204155_0777/
Examining task ID: task_1354923204155_0777_m_000000 (and more) from job
job_1354923204155_0777
Task with the most failures(4):
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Task ID:
task_1354923204155_0777_m_000000
URL:
http://0.0.0.0:8088/taskdetails.jsp?jobid=job_1354923204155_0777&tipid=task_1354923204155_0777_m_000000
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Diagnostic Messages for this Task:
Error: Java heap space
{noformat}
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