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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3907) Save useful length information for Clobs in store
Date Wed, 26 Nov 2008 18:04:46 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12651080#action_12651080
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Knut Anders Hatlen commented on DERBY-3907:
-------------------------------------------

I think the magic byte sounds like an elegant solution to the problem. The invalid values
for the first byte in the UTF-8-encoded sequence are used almost as if we had half a byte
extra in the header reserved for future use. I think you are right that this will make the
backwards-compatibility issues much easier to handle. As to your question about picking the
right format when writing, I think your approach of checking the version of the data dictionary
is the way it's normally done.

> 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
>         Attachments: derby-3907-1a-alternative_approach.diff
>
>
> 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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