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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-3623) Hive query hangs with limit 0 clause
Date Wed, 28 Oct 2015 20:46:27 GMT

    [ https://issues.apache.org/jira/browse/DRILL-3623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14979198#comment-14979198
] 

ASF GitHub Bot commented on DRILL-3623:
---------------------------------------

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

    https://github.com/apache/drill/pull/193#discussion_r43315255
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/sql/handlers/FindLimit0Visitor.java
---
    @@ -46,6 +51,32 @@ public static boolean containsLimit0(RelNode rel) {
         return visitor.isContains();
       }
     
    +  public static DrillRel addLimitOnTopOfLeafNodes(final DrillRel rel) {
    +    final RelShuttleImpl shuttle = new RelShuttleImpl() {
    +
    +      private RelNode addLimitAsParent(RelNode node) {
    +        final RexBuilder builder = node.getCluster().getRexBuilder();
    +        final RexLiteral offset = builder.makeExactLiteral(BigDecimal.ZERO);
    +        final RexLiteral fetch = builder.makeExactLiteral(BigDecimal.ZERO);
    +        return new DrillLimitRel(node.getCluster(), node.getTraitSet(), node, offset,
fetch);
    --- End diff --
    
    I understand in your case, you only putDrillLimitRel. But you may want to make this Visitor
more general, such that it could create any kind of LimitRel, including DrillLimitRel, LogicalLimitRel,
DrillLimitPrel, etc. You can do that by define a LimitFactory, and pass to this Visitor. This's
similar to what other Calcite rule would do, to make the code more general. 


> Hive query hangs with limit 0 clause
> ------------------------------------
>
>                 Key: DRILL-3623
>                 URL: https://issues.apache.org/jira/browse/DRILL-3623
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Storage - Hive
>    Affects Versions: 1.1.0
>         Environment: MapR cluster
>            Reporter: Andries Engelbrecht
>            Assignee: Jinfeng Ni
>             Fix For: Future
>
>
> Running a select * from hive.table limit 0 does not return (hangs).
> Select * from hive.table limit 1 works fine
> Hive table is about 6GB with 330 files with parquet using snappy compression.
> Data types are int, bigint, string and double.
> Querying directory with parquet files through the DFS plugin works fine
> select * from dfs.root.`/user/hive/warehouse/database/table` limit 0;



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