db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-3907) Save useful length information for Clobs in store
Date Fri, 23 Jan 2009 09:48:59 GMT

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

Kristian Waagan updated DERBY-3907:
-----------------------------------

    Attachment: derby-3907-7a3-use_new_header_format.stat
                derby-3907-7a3-use_new_header_format.diff

Patch 7a3 is the patch that enables the new header format.
I plan to commit this Tuesday or Wednesday next week.

Patch ready for review.

Remaining work:
 o Determine if the database version should be kept in the Database object.
    It all depends on how expensive it is to consult the data dictionary about the version.
 o Investigate upgrade further to understand whether long columns can easily be upgraded with
a new header or not.
 o (stretch task) Investigate how to add the functionality to update only the first few bytes
of a data value.

NOTE: After this patch has been committed, databases containing CLOBs written with a Derby
revision after the commit cannot be read with a Derby revision before the commit.

> 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
>             Fix For: 10.5.0.0
>
>         Attachments: derby-3907-1a-alternative_approach.diff, derby-3907-2b-header_write_preparation.diff,
derby-3907-2b-header_write_preparation.diff, derby-3907-2b-header_write_preparation.stat,
derby-3907-2c-header_write_preparation-PREVIEW.diff, derby-3907-2c-header_write_preparation-PREVIEW.stat,
derby-3907-2c-header_write_preparation.diff, derby-3907-2c-header_write_preparation.diff,
derby-3907-2c-header_write_preparation.stat, derby-3907-3a-readertoutf8stream_cleanup.diff,
derby-3907-3a-readertoutf8stream_cleanup.diff, derby-3907-3a-readertoutf8stream_cleanup.stat,
derby-3907-3b-readertoutf8stream_cleanup.diff, derby-3907-4a-add_getStreamWithDescriptor.diff,
derby-3907-4a-add_getStreamWithDescriptor.stat, derby-3907-5a-use_getStreamWithDescriptor.diff,
derby-3907-5a-use_getStreamWithDescriptor.stat, derby-3907-6a-SQLClob_stream_descriptor_sync.diff,
derby-3907-7a-write_new_header_format-PREVIEW.diff, derby-3907-7a-write_new_header_format.diff,
derby-3907-7a-write_new_header_format.diff, derby-3907-7a-write_new_header_format.stat, derby-3907-7a1-write_new_header_format.diff,
derby-3907-7a2-use_new_framework.diff, derby-3907-7a2-use_new_framework.stat, derby-3907-7a3-use_new_header_format.diff,
derby-3907-7a3-use_new_header_format.stat
>
>
> 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.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message