[jira] [Created] (DRILL-5891) When Drill runs out of memory for a HashAgg, it should tell the user how much memory to allocate

["Robert Hou (JIRA)" <ji...@apache.org>]

Robert Hou created DRILL-5891:
---------------------------------

             Summary: When Drill runs out of memory for a HashAgg, it should tell the user how much memory to allocate
                 Key: DRILL-5891
                 URL: https://issues.apache.org/jira/browse/DRILL-5891
             Project: Apache Drill
          Issue Type: Bug
          Components: Execution - Relational Operators
    Affects Versions: 1.11.0
            Reporter: Robert Hou
            Assignee: Pritesh Maker


Query is:
select count(*), max(`filename`) from dfs.`/drill/testdata/hash-agg/data1` group by no_nulls_col, nulls_col;

Error is:
Error: RESOURCE ERROR: Not enough memory for internal partitioning and fallback mechanism for HashAgg to use unbounded memory is disabled. Either enable fallback config drill.exec.hashagg.fallback.enabled using Alter session/system command or increase memory limit for Drillbit

From drillbit.log:
{noformat}
2017-10-18 13:30:17,135 [26184629-3f4c-856a-e99e-97cdf0d29321:frag:1:8] TRACE o.a.d.e.p.i.aggregate.HashAggregator - Incoming sizer: Actual batch schema & sizes {
  no_nulls_col(type: OPTIONAL VARCHAR, count: 1023, std size: 54, actual size: 130, data size: 132892)
  nulls_col(type: OPTIONAL VARCHAR, count: 1023, std size: 54, actual size: 112, data size: 113673)
  EXPR$0(type: REQUIRED BIGINT, count: 1023, std size: 8, actual size: 8, data size: 8184)
  EXPR$1(type: OPTIONAL VARCHAR, count: 1023, std size: 54, actual size: 18, data size: 18414)
  Records: 1023, Total size: 524288, Data size: 273163, Gross row width: 513, Net row width: 268, Density: 53%}
2017-10-18 13:30:17,135 [26184629-3f4c-856a-e99e-97cdf0d29321:frag:1:8] TRACE o.a.d.e.p.i.aggregate.HashAggregator - 2nd phase. Estimated internal row width: 166 Values row width: 66 batch size: 12779520  memory limit: 63161283  max column width: 50
2017-10-18 13:30:17,139 [26184629-3f4c-856a-e99e-97cdf0d29321:frag:3:2] TRACE o.a.d.e.p.impl.common.HashTable - HT allocated 4784128 for varchar of max width 50
2017-10-18 13:30:17,139 [26184629-3f4c-856a-e99e-97cdf0d29321:frag:1:15] INFO  o.a.d.e.p.i.aggregate.HashAggregator - User Error Occurred: Not enough memory for internal partitioning and fallback mechanism for HashAgg to use unbounded memory is disabled. Either enable fallback config drill.exec.hashagg.fallback.enabled using Alter session/system command or increase memory limit for Drillbit
org.apache.drill.common.exceptions.UserException: RESOURCE ERROR: Not enough memory for internal partitioning and fallback mechanism for HashAgg to use unbounded memory is disabled. Either enable fallback config drill.exec.hashagg.fallback.enabled using Alter session/system command or increase memory limit for Drillbit
{noformat}

I would recommend that we add a log message with the "alter" command to increase the amount of memory allocated, and how much memory to allocate.  Otherwise, the user may not know what to do.

I would also not suggest enabling "drill.exec.hashagg.fallback.enabled" except as a last resort.



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