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https://issues.apache.org/jira/browse/SPARK-21784?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17166401#comment-17166401
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Hamad Javed commented on SPARK-21784:
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Hey [~ksunitha], I would be really interested in having this feature added in
spark. Having primary keys defined is a strong feature in a lot of traditional
Databases and porting it over to spark would very useful - we can eliminate a
whole class of problems simply by knowing and enforcing primary key
constraints.
> Add ALTER TABLE ADD CONSTRANT DDL to support defining primary key and foreign
> keys
> ----------------------------------------------------------------------------------
>
> Key: SPARK-21784
> URL: https://issues.apache.org/jira/browse/SPARK-21784
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 3.1.0
> Reporter: Suresh Thalamati
> Priority: Major
>
> Currently Spark SQL does not have DDL support to define primary key , and
> foreign key constraints. This Jira is to add DDL support to define primary
> key and foreign key informational constraint using ALTER TABLE syntax. These
> constraints will be used in query optimization and you can find more details
> about this in the spec in SPARK-19842
> *Syntax :*
> {code}
> ALTER TABLE [db_name.]table_name ADD [CONSTRAINT constraintName]
> (PRIMARY KEY (col_names) |
> FOREIGN KEY (col_names) REFERENCES [db_name.]table_name [(col_names)])
> [VALIDATE | NOVALIDATE] [RELY | NORELY]
> {code}
> Examples :
> {code:sql}
> ALTER TABLE employee _ADD CONSTRANT pk_ PRIMARY KEY(empno) VALIDATE RELY
> ALTER TABLE department _ADD CONSTRAINT emp_fk_ FOREIGN KEY (mgrno) REFERENCES
> employee(empno) NOVALIDATE NORELY
> {code}
> *Constraint name generated by the system:*
> {code:sql}
> ALTER TABLE department ADD PRIMARY KEY(deptno) VALIDATE RELY
> ALTER TABLE employee ADD FOREIGN KEY (workdept) REFERENCES department(deptno)
> VALIDATE RELY;
> {code}
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