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From "Carter Shanklin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-16575) Support for 'UNIQUE' and 'NOT NULL' constraints
Date Thu, 04 May 2017 14:28:04 GMT

    [ https://issues.apache.org/jira/browse/HIVE-16575?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15996805#comment-15996805
] 

Carter Shanklin commented on HIVE-16575:
----------------------------------------

[~jcamachorodriguez] A note on the standard:

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.

Second thing, since NOT NULL is so common it would be great to have transactional tables start
to enforce that. Possibly follow up work. /cc [~ekoifman]

> Support for 'UNIQUE' and 'NOT NULL' constraints
> -----------------------------------------------
>
>                 Key: HIVE-16575
>                 URL: https://issues.apache.org/jira/browse/HIVE-16575
>             Project: Hive
>          Issue Type: New Feature
>          Components: CBO, Logical Optimizer, Parser
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>         Attachments: HIVE-16575.01.patch, HIVE-16575.patch
>
>
> Follow-up on HIVE-13076.
> This issue add support for SQL 'UNIQUE' and 'NOT NULL' constraints when we create a table
/ alter a table (https://www.postgresql.org/docs/9.6/static/sql-createtable.html).
> As with PK and FK constraints, currently we do not enforce them; thus, the constraints
need to use the DISABLE option, but they will be stored and can be enabled for rewriting/optimization
using RELY.
> This patch also adds support for inlining the constraints next to the column type definition,
i.e., 'column constraints'.
> Some examples of the extension to the syntax included in the patch:
> {code:sql}
> CREATE TABLE table3 (x string NOT NULL DISABLE, PRIMARY KEY (x) DISABLE, CONSTRAINT fk1
FOREIGN KEY (x) REFERENCES table2(a) DISABLE); 
> CREATE TABLE table4 (x string CONSTRAINT nn4_1 NOT NULL DISABLE, y string CONSTRAINT
nn4_2 NOT NULL DISABLE, UNIQUE (x) DISABLE, CONSTRAINT fk2 FOREIGN KEY (x) REFERENCES table2(a)
DISABLE, 
> CONSTRAINT fk3 FOREIGN KEY (y) REFERENCES table2(a) DISABLE);
> CREATE TABLE table12 (a STRING CONSTRAINT nn12_1 NOT NULL DISABLE NORELY, b STRING);
> CREATE TABLE table13 (a STRING NOT NULL DISABLE RELY, b STRING);
> CREATE TABLE table14 (a STRING CONSTRAINT nn14_1 NOT NULL DISABLE RELY, b STRING);
> CREATE TABLE table15 (a STRING REFERENCES table4(x) DISABLE, b STRING);
> CREATE TABLE table16 (a STRING CONSTRAINT nn16_1 REFERENCES table4(x) DISABLE RELY, b
STRING);
> ALTER TABLE table16 CHANGE a a STRING REFERENCES table4(x) DISABLE NOVALIDATE;
> ALTER TABLE table12 CHANGE COLUMN b b STRING CONSTRAINT nn12_2 NOT NULL DISABLE NOVALIDATE;
> ALTER TABLE table13 CHANGE b b STRING NOT NULL DISABLE NOVALIDATE;
> {code}



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