[jira] [Created] (HIVE-20333) CBO: Join removal based on PK-FK declared constraints

["Gopal V (JIRA)" <ji...@apache.org>]

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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