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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-268) Add Support for truncate table
Date Wed, 29 Sep 2010 13:04:34 GMT

    [ https://issues.apache.org/jira/browse/DERBY-268?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12916134#action_12916134

Rick Hillegas commented on DERBY-268:

Hi Eranda,

No need to touch ij, all of this code should be in the engine. The good news is that both
TRUNCATE TABLE and ALTER TABLE ALTER COLUMN RESTART are handled by the AlterTableConstantAction
machinery at run time. If I were tackling this, I would first try something along these lines:

o AlterTableNode.bindStatement() will need to build a tableElementList structure for TRUNCATE
TABLE, describing the identity column which needs to be re-initialized. For ALTER TABLE ALTER
COLUMN RESTART, that tableElementList is created by the parser.

o That tableElementList structure will then be picked up by AlterTableNode.prepConstantAction
and turned into a ColumnInfo array when the run time structures are generated for TRUNCATE
TABLE. The ColumnInfo[] structure should contain enough information to describe the change
to the identity column.

o The column info structure will then be processed by AlterTableConstantAction.executeConstantAction()
at run time.

You may need to tweak the code a bit to get this to function, but I think this basic processing
flow should work. Please ask more questions if this is too cryptic.

Hope this helps,

> Add Support for truncate table
> ------------------------------
>                 Key: DERBY-268
>                 URL: https://issues.apache.org/jira/browse/DERBY-268
>             Project: Derby
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Lance Andersen
>            Assignee: Eranda Sooriyabandara
>            Priority: Minor
>         Attachments: derby-268-01-ab-enableForInsaneBuilds.diff, derby-268-02-aa-permsTest.diff,
derby-268-03-aa-npe.diff, Derby-268.diff, tests.diff, TruncateConcurrency.java, TruncateConcurrency.java,
> Adding support for truncate table command will aid to portability

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