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From "Mike Matrigali (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-4256) allow alter table to increase the maximum size of a blob and a clob.
Date Wed, 03 Jun 2009 17:10:07 GMT

     [ https://issues.apache.org/jira/browse/DERBY-4256?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Mike Matrigali updated DERBY-4256:

    Derby Categories: [Newcomer]

I believe that this project would be a good one for a new comer.  I don't think it would be
too hard.  

I would suggest finding the code path that allows alter table to increase the size of a varchar
field and 
mimic the code to apply to blob and clob fields.  It will require some parser changes and
some execution
time changes.  The files can be pointed out if necessary.

What makes this easy is to only allow INCREASE of size.  For blob and clob the size field
is really only used
for error checking at the higher levels of the code, there is no storage difference between
a small one and
a large one.  No format difference.  Also no space difference as we only use space to store
whatever the
actual size is.  By only allowing increase then there is no need to go and check the length
of every value, and
figure out what to do if there exists a value that exceeds the new proposed maximum.

> allow alter table to increase the maximum size of a blob and a clob.
> --------------------------------------------------------------------
>                 Key: DERBY-4256
>                 URL: https://issues.apache.org/jira/browse/DERBY-4256
>             Project: Derby
>          Issue Type: New Feature
>    Affects Versions:
>            Reporter: Mike Matrigali
>            Priority: Minor
> Allow new syntax that allows user to alter the maximum length of a blob and/or clob column:
> ALTER TABLE binarydata ALTER COLUMN data SET DATA TYPE blob(128M)
> The syntax should match up with the existing functionality to increase the size of varchar

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