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https://issues.apache.org/jira/browse/HIVE-26582?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17612658#comment-17612658
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Stamatis Zampetakis commented on HIVE-26582:
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[~kkasa] Checking if the stats are up to date is not a responsibility of the
rule but the metadata provider. If the stats cannot be trusted then the
metadata provider should return an appropriate value (null or something
different according to the API). There are already various rules which base
their decision on the metadata both in Hive and Calcite (e.g.,
https://github.com/apache/hive/blob/95d088a752f1c04f33c9c56556f0f939a1c9ea42/ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveSubQueryRemoveRule.java#L176)
so adding more similar rules should be fine.
> Cartesian join fails if the query has an empty table when cartesian product
> edge is used
> ----------------------------------------------------------------------------------------
>
> Key: HIVE-26582
> URL: https://issues.apache.org/jira/browse/HIVE-26582
> Project: Hive
> Issue Type: Bug
> Components: Hive, Tez
> Reporter: Sourabh Badhya
> Priority: Major
>
> The following example fails when "hive.tez.cartesian-product.enabled" is true
> -
> Test command -
> {code:java}
> mvn test -Dtest=TestMiniLlapCliDriver -Dqfile=file.q
> -Dtest.output.overwrite=true {code}
> Query - file.q
> {code:java}
> set hive.tez.cartesian-product.enabled=true;
> create table c (a1 int) stored as orc;
> create table tmp1 (a int) stored as orc;
> create table tmp2 (a int) stored as orc;
> insert into table c values (3);
> insert into table tmp1 values (3);
> with
> first as (
> select a1 from c where a1 = 3
> ),
> second as (
> select a from tmp1
> union all
> select a from tmp2
> )
> select a from second cross join first; {code}
> The following stack trace is seen -
> {code:java}
> Caused by: java.lang.IllegalArgumentException: Number of items is 0. Should
> be positive
> at
> org.apache.tez.common.Preconditions.checkArgument(Preconditions.java:38)
> at org.apache.tez.runtime.library.utils.Grouper.init(Grouper.java:41)
> at
> org.apache.tez.runtime.library.cartesianproduct.FairCartesianProductEdgeManager.initialize(FairCartesianProductEdgeManager.java:66)
> at
> org.apache.tez.runtime.library.cartesianproduct.CartesianProductEdgeManager.initialize(CartesianProductEdgeManager.java:51)
> at org.apache.tez.dag.app.dag.impl.Edge.initialize(Edge.java:213)
> ... 22 more{code}
> The following error is seen because one of the tables (tmp2 in this case) has
> 0 rows in it.
> The query works fine when the config hive.tez.cartesian-product.enabled is
> set to false.
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