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From "Daniel John Debrunner (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-1516) Inconsistent behavior for getBytes and getSubString for embedded versus network
Date Tue, 08 Aug 2006 16:15:15 GMT
    [ http://issues.apache.org/jira/browse/DERBY-1516?page=comments#action_12426621 ] 
            
Daniel John Debrunner commented on DERBY-1516:
----------------------------------------------

Since this has been a tricky area to get correct, it seems that adding Javadoc comments to
the methods your are modifying in the Derby implementations of Clob & Blob would add great
value. Otherwise a few months from now someone may change the code again thinking it is wrong
(especially since the code no longer matches the javadoc).

In Derby's JDBC implementation notes this comment exists for getSubString

http://db.apache.org/derby/papers/JDBCImplementation.html#getSubString%28int+pos%2C+int+length%29

If the pos (position) argument is greater than the length of the CLOB then an exception is
thrown. This matches the semantics of the SQL SUBSTR function.

Does that need to be corrected, do we have an issue because the new code will not match SQL
SUBSTR?

> Inconsistent behavior for getBytes and getSubString for embedded versus network
> -------------------------------------------------------------------------------
>
>                 Key: DERBY-1516
>                 URL: http://issues.apache.org/jira/browse/DERBY-1516
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC
>            Reporter: Craig Russell
>         Assigned To: Craig Russell
>            Priority: Minor
>         Attachments: DERBY-1516.patch, DERBY-1516.patch, DERBY-1516.patch, DERBY-1516.patch,
DERBY-1516.patch
>
>
> org.apache.derby.client.am.Clob.getSubString(pos, length) and org.apache.derby.client.am.Blob.getBytes(pos,
length) check the length for less than zero. 
>             if ((pos <= 0) || (length < 0)) {
>                 throw new SqlException(agent_.logWriter_, "Invalid position " + pos +
" or length " + length);
> But org.apache.derby.impl.jdbc.EmbedClob(pos, length) and org.apache.derby.impl.jdbc.EmbedBlob(pos,
length) check the length for less than or equal to zero.
>        if (length <= 0)
>             throw Util.generateCsSQLException(
>                 SQLState.BLOB_NONPOSITIVE_LENGTH, new Integer(length));
> The specification does not disallow length of zero, so zero length should be allowed.
I believe that the implementation in org.apache.derby.client.am is correct, and the implementation
in org.apache.derby.impl.jdbc is incorrect. 

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