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From "Mike Matrigali (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3907) Save useful length information for Clobs in store
Date Fri, 10 Oct 2008 17:11:44 GMT

     [ https://issues.apache.org/jira/browse/DERBY-3907?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Mike Matrigali updated DERBY-3907:
----------------------------------


I will post some more comments on your proposal, but need some clarification.

What does the following mean?  Will the changes apply to all sql which inserts clobs, or to
only particular jdbc interfaces?
1) Clob modifications are done on a copy (i.e. TemporaryClob).

What is the expected call sequence to store, and what is the goal performance characteristic?
 ie.
for an insert of non-lengthed clob is it something like:
insert unlength clob into store, calculating length along the way
update clob in store changing N leading bytes



> Save useful length information for Clobs in store
> -------------------------------------------------
>
>                 Key: DERBY-3907
>                 URL: https://issues.apache.org/jira/browse/DERBY-3907
>             Project: Derby
>          Issue Type: Improvement
>          Components: JDBC, Store
>    Affects Versions: 10.5.0.0
>            Reporter: Kristian Waagan
>            Assignee: Kristian Waagan
>
> The store should save useful length information for Clobs. This allows the length to
be found without decoding the whole data stream.
> The following thread raised the issue on what information to store, and also contains
some background information: http://www.nabble.com/Storing-length-information-for-CLOB-on-disk-tp19197535p19197535.html
> The information to store, and the exact format of it, is still to be discussed/determined.
> Currently two bytes are set aside for length information, which is inadequate.

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