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From "Jesus Camacho Rodriguez (JIRA)" <>
Subject [jira] [Commented] (HIVE-16604) Use [NOT] ENFORCED for column constraint characteristics
Date Mon, 08 May 2017 11:14:04 GMT


Jesus Camacho Rodriguez commented on HIVE-16604:

We could replace ENABLE/DISABLE by [NOT] ENFORCED, since they have a similar goal but the
latest is SQL standard compliant. If we want to remain backwards compatible, we could just
add [NOT] ENFORCED as an additional syntax, although this might add some confusion for end
user. [~ashutoshc], what is your take? In both cases, only changes at the parser level are
needed, we will not change the way that we store the constraints in the metastore.

VALIDATE and NOVALIDATE are used to ensure that existing data in a given table conform to
the constraint, thus they are only used in ALTER table statements when we add a new constraint.
Although maybe the standard does not define anything similar, I think it is valuable to keep
those options, since otherwise an ALTER statement will always have to do a full scan on the
table data to validate that a constraint is not violated, which a user might want to avoid
in some cases.

RELY and NORELY seem valuable too to make the constraints visible for the query optimizer,
thus they can remain.

> Use [NOT] ENFORCED for column constraint characteristics
> --------------------------------------------------------
>                 Key: HIVE-16604
>                 URL:
>             Project: Hive
>          Issue Type: Improvement
>    Affects Versions: 3.0.0
>            Reporter: Carter Shanklin
>            Assignee: Jesus Camacho Rodriguez
> From HIVE-16575:
> {quote}
> SQL:2011 spec, 10.8, uses [ NOT ] ENFORCED for column constraint characteristics.
> I think Oracle invented DISABLE and NORELY and maybe others have copied it over time.
> A quick check I see DB2 uses the [ NOT ] ENFORCED. Teradata uses something else entirely.
> Personally I think there are advantages to adopting the standard approach.
> There is no standard approach for hinting the optimizer so we're on our own there.
> {quote}

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