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https://issues.apache.org/jira/browse/DERBY-481?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12644368#action_12644368
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Dag H. Wanvik commented on DERBY-481:
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I tried this fragment which seems to be forbidden by section 11.8, SR 12a),
p.549:
create table bar2 (i int, j int generated always as (i*2) references foo(i) on
delete set null);
The "set null" part here is not flagged, but probably should be (conflict with
generated clause)?
Sorry if this is pending work, I am just working my way through the standard
;-)
> 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,
> 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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