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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-481) implement SQL generated columns
Date Mon, 03 Nov 2008 18:58:44 GMT

     [ https://issues.apache.org/jira/browse/DERBY-481?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Rick Hillegas updated DERBY-481:
--------------------------------

    Attachment: derby-481-10-aa-foreignKeyActions.diff

Attaching derby-481-10-aa-foreignKeyActions.diff. Running tests now. This patch addresses
the second issue which Dag raised, preventing users from adding foreign keys on generated
columns when the foreign keys have SET NULL or SET DEFAULT delete actions.

M      java/engine/org/apache/derby/impl/sql/compile/TableElementList.java

Adds a method to identify and raise exceptions on these forbidden foreign keys.


M      java/engine/org/apache/derby/impl/sql/compile/AlterTableNode.java
M      java/engine/org/apache/derby/impl/sql/compile/CreateTableNode.java

Wires the new method into the bind-time logic for CREATE/ALTER TABLE.


M      java/engine/org/apache/derby/loc/messages.xml
M      java/shared/org/apache/derby/shared/common/reference/SQLState.java

Adds a new error message for the illegal foreign keys.


M      java/testing/org/apache/derbyTesting/functionTests/tests/lang/GeneratedColumnsTest.java

Adds tests for the illegal foreign keys.


> implement SQL generated columns
> -------------------------------
>
>                 Key: DERBY-481
>                 URL: https://issues.apache.org/jira/browse/DERBY-481
>             Project: Derby
>          Issue Type: New Feature
>          Components: SQL
>    Affects Versions: 10.0.2.1
>            Reporter: Rick Hillegas
>            Assignee: Rick Hillegas
>         Attachments: derby-481-00-aa-prototype.diff, derby-481-01-aa-catalog.diff, derby-481-02-aa-utilities.diff,
derby-481-03-aa-grammar.diff, derby-481-04-aa-insert.diff, derby-481-05-aa-update.diff, derby-481-06-aa-genreferences.diff,
derby-481-07-aa-noSQLinRoutines.diff, derby-481-07-ab-noSQLinRoutines.diff, derby-481-08-aa-castToDeclaredType.diff,
derby-481-09-aa-dummyDefaults.diff, derby-481-10-aa-foreignKeyActions.diff, GeneratedColumns.html
>
>
> Satheesh has pointed out that generated columns, a SQL 2003 feature, would satisfy the
performance requirements of Expression Indexes (bug 455). Generated columns may not be as
elegant as Expression Indexes, but they are easier to implement. We would allow the following
new kind of column definition in CREATE TABLE and ALTER TABLE statements:
>     columnName GENERATED ALWAYS AS ( expression )
> If expression were an indexableExpression (as defined in bug 455), then we could create
indexes on it. There is no work for the optimizer to do here. The Language merely has to compute
the generated column at INSERT/UPDATE time.

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