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Posted to issues@drill.apache.org by "Sorabh Hamirwasia (JIRA)" <ji...@apache.org> on 2017/08/23 01:21:00 UTC
[jira] [Assigned] (DRILL-5737) Hash Agg uses more than the
allocated memory under certain low memory conditions
[ https://issues.apache.org/jira/browse/DRILL-5737?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Sorabh Hamirwasia reassigned DRILL-5737:
----------------------------------------
Assignee: Sorabh Hamirwasia
> Hash Agg uses more than the allocated memory under certain low memory conditions
> --------------------------------------------------------------------------------
>
> Key: DRILL-5737
> URL: https://issues.apache.org/jira/browse/DRILL-5737
> Project: Apache Drill
> Issue Type: Bug
> Reporter: Sorabh Hamirwasia
> Assignee: Sorabh Hamirwasia
>
> Reported by [~rkins]
> Based on the memory computations drill thinks that there is not sufficient memory and falls back to a single partition case. The single partition case however does not respect the memory constraints imposed and completes the query using ~130MB of memory
> {code:java}
> alter session set `planner.width.max_per_node` = 1;
> alter session set `planner.memory.max_query_memory_per_node` = 117127360;
> select count(*) from (select max(nulls_col), max(length(nulls_col)), max(`filename`) from dfs.`/drill/testdata/hash-agg/data1` group by no_nulls_col) d;
> {code}
> Based on analysis by [~ben-zvi] this is by design. When the Hash Aggr Op finds that there is not enough memory for at least two partitions, it falls back to the pre 1.11 behavior ( using 10GB limit ).
> Solution is to provide a configuration based on which the fallback will be either allowed or query will be failed.
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