drill-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4743) HashJoin's not fully parallelized in query plan
Date Mon, 18 Jul 2016 19:02:20 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4743?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15382839#comment-15382839
] 

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

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

    https://github.com/apache/drill/pull/534#discussion_r71207876
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/server/options/TypeValidators.java
---
    @@ -90,6 +91,62 @@ public void validate(OptionValue v) {
         }
       }
     
    +  public static class MinRangeDoubleValidator extends RangeDoubleValidator {
    +    private final double min;
    +    private final double max;
    +    private final String maxValidatorName;
    +
    +    public MinRangeDoubleValidator(String name, double min, double max, double def, String
maxValidatorName) {
    +      super(name, min, max, def);
    +      this.min = min;
    +      this.max = max;
    +      this.maxValidatorName = maxValidatorName;
    +    }
    +
    +    @Override
    +    public void validate(OptionValue v, final OptionManager manager) {
    +      super.validate(v, manager);
    +      if (manager != null) {
    --- End diff --
    
    Is this null check necessary?


> 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)

Mime
View raw message