Gopal V created HIVE-20333:
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Summary: CBO: Join removal based on PK-FK declared constraints
Key: HIVE-20333
URL: https://issues.apache.org/jira/browse/HIVE-20333
Project: Hive
Issue Type: Bug
Reporter: Gopal V
A query of the following shape can have its customer join removed entirely on
the basis of the key containment between customer & store_sales.
{code}
select c_customer_sk,sum(ss_quantity*ss_sales_price) ssales from store_sales
,customer where ss_customer_sk = c_customer_sk group by c_customer_sk;
{code}
This query after join removal can be encoded in as
{code}
select ss_customer_sk as c_customer_sk,sum(ss_quantity*ss_sales_price) ssales
from store_sales where ss_customer_sk is not null group by ss_customer_sk;
{code}
The rewrite is not applied today and the current PK-FK relationship does not
allow for a nullable relationship (i.e a declared Foreign Key can't be NULL).
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