[
https://issues.apache.org/jira/browse/HIVE-26524?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Krisztian Kasa updated HIVE-26524:
----------------------------------
Description:
Calcite has a set of rules to remove sections of a query plan known never
produces any rows. In some cases the whole plan can be removed. Such plans are
represented with a single {{Values}} operators with no tuples. ex.:
{code:java}
select y + 1 from (select a1 y, b1 z from t1 where b1 > 10) q WHERE 1=0
{code}
{code:java}
HiveValues(tuples=[[]])
{code}
Other cases when plan has outer join or set operators some branches can be
replaced with empty values moving forward in some cases the join/set operator
can be removed
{code:java}
select a2, b2 from t2 where 1=0
union
select a1, b1 from t1
{code}
{code:java}
HiveAggregate(group=[{0, 1}])
HiveTableScan(table=[[default, t1]], table:alias=[t1])
{code}
was:
Calcite has a set of rules to remove sections of a query plan known never
produces any rows. In some cases the whole plan can be removed. Such plans are
represented with a single {{Values}} operators with no tuples. ex.:
{code}
select y + 1 from (select a1 y, b1 z from t1 where b1 > 10) q WHERE 1=0
{code}
{code}
HiveValues(tuples=[[]])
{code}
Other cases when plan has outer join or set operators some branches can be
replaced with empty values moving forward the join/set operator can be removed
{code}
select a2, b2 from t2 where 1=0
union
select a1, b1 from t1
{code}
{code}
HiveAggregate(group=[{0, 1}])
HiveTableScan(table=[[default, t1]], table:alias=[t1])
{code}
> Use Calcite to remove sections of a query plan known never produces rows
> ------------------------------------------------------------------------
>
> Key: HIVE-26524
> URL: https://issues.apache.org/jira/browse/HIVE-26524
> Project: Hive
> Issue Type: Improvement
> Components: CBO
> Reporter: Krisztian Kasa
> Assignee: Krisztian Kasa
> Priority: Major
>
> Calcite has a set of rules to remove sections of a query plan known never
> produces any rows. In some cases the whole plan can be removed. Such plans
> are represented with a single {{Values}} operators with no tuples. ex.:
> {code:java}
> select y + 1 from (select a1 y, b1 z from t1 where b1 > 10) q WHERE 1=0
> {code}
> {code:java}
> HiveValues(tuples=[[]])
> {code}
> Other cases when plan has outer join or set operators some branches can be
> replaced with empty values moving forward in some cases the join/set operator
> can be removed
> {code:java}
> select a2, b2 from t2 where 1=0
> union
> select a1, b1 from t1
> {code}
> {code:java}
> HiveAggregate(group=[{0, 1}])
> HiveTableScan(table=[[default, t1]], table:alias=[t1])
> {code}
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
