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https://issues.apache.org/jira/browse/DERBY-3583?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12584289#action_12584289
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Kristian Waagan commented on DERBY-3583:
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As I noted in DERBY-3571, I believe that patch should make it a lot easier to
support either option.
When it comes to which option to choose, I'm not sure.
These are some of my thoughts (in random order):
1) Allowing only a single call forces more portable code.
2) Allowing multiple calls makes the client driver consistent with the
embedded driver.
3) Allowing multiple calls is more convenient.
4) Allowing multiple calls might have some side-effects if two LOB objects are
used concurrently (?).
Seems like I'm more in favor of allowing multiple calls, so I guess I would go
for that if it works technically.
Regarding the comment about the other get methods (String, Bytes, XStream), I
don't think they are disallowed because the locator is freed. That is just how
it is implemented, and it's in line with the spec to close the streams.
I think it might be just as good to let the LOB tracker release the locators.
The only case where the locators cannot be released implicitly, is when a Blob
or Clob object is published to the user.
As soon as DERBY-3571 is resolved, I can post a patch demonstrating the
approach.
> Derby should throw a better error message if a BLOB/CLOB column is accessed
> more than once
> ------------------------------------------------------------------------------------------
>
> Key: DERBY-3583
> URL: https://issues.apache.org/jira/browse/DERBY-3583
> Project: Derby
> Issue Type: Improvement
> Reporter: Kathey Marsden
> Assignee: Kathey Marsden
> Priority: Minor
>
> With the DERBY-2892 fix revision 642974, users can no longer access a
> BLOB/CLOB column more than once for each row. Currently the error message is
> XJ217 - You cannot invoke other java.sql.Clob/java.sql.Blob methods after
> calling the free() method or after the Blob/Clob's transaction has been
> committed or rolled back.
> I don't know that that makes sense given the user called getString()
> For getCharacterStream()/getBinaryStream() there is no error on the call,
> just an IOException on the read.
> We should throw a clearer error message, that the user is not allowed to make
> multiple getXXX calls on a BLOB/CLOB column for each row.
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