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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6000) Implement support for JDBC 4.2
Date Fri, 08 Feb 2013 09:05:15 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13574333#comment-13574333

Kristian Waagan commented on DERBY-6000:

> I'll ask Lance if he has any advice about what this method should return on Derby.
> Seems to me there are at least 2 theories about this:
> o 4294967294 - The maximum number of bytes which an in-memory CLOB can consume.
>   This is misleading for people interested in the maximum number of bytes which can be
stored in the database.
> o 2147483647 - The maximum number of bytes in a LOB stored in the database.
>  This is misleading for people who are interested in the memory representation.

My take on this is that people would use this method to figure out how big LOBs they can store
in the database. I don't think they care about representation (i.e. on-disk vs in-memory).
This gives rise to two questions:
 a) How many bytes can I stuff into a single BLOB?
 b) How many characters can I stuff into a single CLOB?

I hope the above is the intention of the method - I fail to immediately see any other meaningful
uses of it.

The answers to (a) and (b) may be different for some databases, for instance because the DBMS
has an internal limitation on how many bytes it can store/handle. Combined with the fact that
one character doesn't always equal one byte, that could make the maximum size of a CLOB data
dependent (i.e. storing English vs Chinese text).
> Implement support for JDBC 4.2
> ------------------------------
>                 Key: DERBY-6000
>                 URL: https://issues.apache.org/jira/browse/DERBY-6000
>             Project: Derby
>          Issue Type: Improvement
>          Components: JDBC
>            Reporter: Rick Hillegas
>         Attachments: derby-6000-01-aa-executeLargeUpdateEmbedded.diff, derby-6000-02-ad-executeLargeUpdateClient.diff,
derby-6000-03-aa-executeLargeBatch.diff, derby-6000-04-aa-setLargeMaxRows.diff, derby-6000-05-aa-executeLargeUpdatePS.diff,
derby-6000-06-aa-DatabaseMetaData.diff, derby-6000-07-ab-batchUpdateException.diff, derby-6000-08-aa-batchUpdateExceptionConstructor.diff,
derby-6000-09-ac-setObjectPS.diff, derby-6000-10-aa-rename_getMaxLogicalLobSize.diff, JDBC_4.2_Changes.html
> Open JDK 8 will include maintenance rev 4.2 of JDBC. The public discussion of JDBC 4.2
will take place here: http://openjdk.java.net/jeps/170. We will want to build Derby support
for JDBC 4.2 after a public spec appears. At this time, it is unclear what Derby release will
carry this support.

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