[jira] [Work logged] (HIVE-24199) Incorrect result when subquey in exists contains limit

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

     [ https://issues.apache.org/jira/browse/HIVE-24199?focusedWorklogId=496240&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-496240 ]

ASF GitHub Bot logged work on HIVE-24199:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 07/Oct/20 00:02
            Start Date: 07/Oct/20 00:02
    Worklog Time Spent: 10m 
      Work Description: vineetgarg02 commented on a change in pull request #1525:
URL: https://github.com/apache/hive/pull/1525#discussion_r500661508



##########
File path: ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveSubQueryRemoveRule.java
##########
@@ -406,6 +409,16 @@ private RexNode rewriteInExists(RexSubQuery e, Set<CorrelationId> variablesSet,
         offset = offset + 1;
         builder.push(e.rel);
       }
+    } else if (e.getKind() == SqlKind.EXISTS && !variablesSet.isEmpty()) {
+      // Query has 'exists' and correlation:

Review comment:
       Can you add a comment to explain/mention why limit is being removed for correlated EXISTs?




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Issue Time Tracking
-------------------

    Worklog Id:     (was: 496240)
    Time Spent: 0.5h  (was: 20m)

> Incorrect result when subquey in exists contains limit
> ------------------------------------------------------
>
>                 Key: HIVE-24199
>                 URL: https://issues.apache.org/jira/browse/HIVE-24199
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Krisztian Kasa
>            Assignee: Krisztian Kasa
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 0.5h
>  Remaining Estimate: 0h
>
> {code:java}
> create table web_sales (ws_order_number int, ws_warehouse_sk int) stored as orc;
> insert into web_sales values
> (1, 1),
> (1, 2),
> (2, 1),
> (2, 2);
> select * from web_sales ws1
> where exists (select 1 from web_sales ws2 where ws1.ws_order_number = ws2.ws_order_number limit 1);
> 1	1
> 1	2
> {code}
> {code:java}
> CBO PLAN:
> HiveSemiJoin(condition=[=($0, $2)], joinType=[semi])
>   HiveProject(ws_order_number=[$0], ws_warehouse_sk=[$1])
>     HiveFilter(condition=[IS NOT NULL($0)])
>       HiveTableScan(table=[[default, web_sales]], table:alias=[ws1])
>   HiveProject(ws_order_number=[$0])
>     HiveSortLimit(fetch=[1])          <-- This shouldn't be added
>       HiveProject(ws_order_number=[$0])
>         HiveFilter(condition=[IS NOT NULL($0)])
>           HiveTableScan(table=[[default, web_sales]], table:alias=[ws2])
> {code}
> Limit n on the right side of the join reduces the result set coming from the right to only n record hence not all the ws_order_number values are included which leads to correctness issue.



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