[jira] [Commented] (DRILL-4743) HashJoin's not fully parallelized in query plan

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-4743?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15371411#comment-15371411 ] 

ASF GitHub Bot commented on DRILL-4743:
---------------------------------------

Github user amansinha100 commented on a diff in the pull request:

    https://github.com/apache/drill/pull/534#discussion_r70316280
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/PlannerSettings.java ---
    @@ -81,6 +81,11 @@
           new RangeLongValidator("planner.identifier_max_length", 128 /* A minimum length is needed because option names are identifiers themselves */,
                                   Integer.MAX_VALUE, DEFAULT_IDENTIFIER_MAX_LENGTH);
     
    +  public static final OptionValidator FILTER_MIN_SELECTIVITY_ESTIMATE_FACTOR = new RangeDoubleValidator("planner.filter.min_selectivity_estimate_factor",
    +          0.0, 1.0, 0.0d);
    +  public static final OptionValidator FILTER_MAX_SELECTIVITY_ESTIMATE_FACTOR = new RangeDoubleValidator("planner.filter.max_selectivity_estimate_factor",
    --- End diff --
    
    can you add validation if the min does not exceed the max and vice versa. 


> HashJoin's not fully parallelized in query plan
> -----------------------------------------------
>
>                 Key: DRILL-4743
>                 URL: https://issues.apache.org/jira/browse/DRILL-4743
>             Project: Apache Drill
>          Issue Type: Bug
>    Affects Versions: 1.5.0
>            Reporter: Gautam Kumar Parai
>            Assignee: Gautam Kumar Parai
>              Labels: doc-impacting
>
> The underlying problem is filter selectivity under-estimate for a query with complicated predicates e.g. deeply nested and/or predicates. This leads to under parallelization of the major fragment doing the join. 
> To really resolve this problem we need table/column statistics to correctly estimate the selectivity. However, in the absence of statistics OR even when existing statistics are insufficient to get a correct estimate of selectivity this will serve as a workaround.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)