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Posted to issues@hive.apache.org by "Alessandro Solimando (Jira)" <ji...@apache.org> on 2022/11/10 15:25:00 UTC
[jira] [Assigned] (HIVE-26722) HiveFilterSetOpTransposeRule incorrectly prune UNION ALL operands
[ https://issues.apache.org/jira/browse/HIVE-26722?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Alessandro Solimando reassigned HIVE-26722:
-------------------------------------------
> HiveFilterSetOpTransposeRule incorrectly prune UNION ALL operands
> -----------------------------------------------------------------
>
> Key: HIVE-26722
> URL: https://issues.apache.org/jira/browse/HIVE-26722
> Project: Hive
> Issue Type: Bug
> Components: CBO
> Affects Versions: 4.0.0-alpha-1
> Reporter: Alessandro Solimando
> Assignee: Alessandro Solimando
> Priority: Major
>
> Consider the following query:
>
> {code:java}
> set hive.cbo.rule.exclusion.regex=ReduceExpressionsRule\(Project\);
> CREATE EXTERNAL TABLE t (a string, b string);
> INSERT INTO t VALUES ('1000', 'b1');
> INSERT INTO t VALUES ('2000', 'b2');
> SELECT * FROM (
> SELECT
> a,
> b
> FROM t
> UNION ALL
> SELECT
> a,
> CAST(NULL AS string)
> FROM t) AS t2
> WHERE a = 1000;EXPLAIN CBO
> SELECT * FROM (
> SELECT
> a,
> b
> FROM t
> UNION ALL
> SELECT
> a,
> CAST(NULL AS string)
> FROM t) AS t2
> WHERE a = 1000; {code}
>
>
> The expected result is:
>
> {code:java}
> 1000 b1
> 1000 NULL{code}
>
> An example of correct plan is as follows:
>
> {noformat}
> CBO PLAN:
> HiveUnion(all=[true])
> HiveProject(a=[$0], b=[$1])
> HiveFilter(condition=[=(CAST($0):DOUBLE, 1000)])
> HiveTableScan(table=[[default, t]], table:alias=[t])
> HiveProject(a=[$0], _o__c1=[null:VARCHAR(2147483647) CHARACTER SET "UTF-16LE"])
> HiveFilter(condition=[=(CAST($0):DOUBLE, 1000)])
> HiveTableScan(table=[[default, t]], table:alias=[t]){noformat}
>
>
> Consider now a scenario where expression reduction in projections is disabled by setting the following property{_}:{_}
> {noformat}
> set hive.cbo.rule.exclusion.regex=ReduceExpressionsRule\(Project\);
> {noformat}
> In this case, the simplification of _CAST(NULL)_ into _NULL_ does not happen, and we get the following (invalid) result:
> 1000 b1
>
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