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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-4544) Referencing streaming CLOBs in (some) generated column clauses fails
Date Wed, 06 Apr 2011 19:52:05 GMT

     [ https://issues.apache.org/jira/browse/DERBY-4544?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Rick Hillegas updated DERBY-4544:
---------------------------------

    Attachment: Test_4544.java

Attaching Test_4544.java. This class demonstrates a problem when you follow the steps described
in this issue. Since Kristian logged this issue, the symptoms of the problem seem to have
changed. The repro shows that Derby raises the following exception when you try to initially
position a ResultSet for reading the corrupt Clob:

Exception in thread "main" java.sql.SQLException: Restore of a serializable or SQLData object
of class , attempted to read more data than was originally stored
	at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(SQLExceptionFactory40.java:98)
	at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Util.java:142)
	at org.apache.derby.impl.jdbc.Util.seeNextException(Util.java:278)
	at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(TransactionResourceImpl.java:403)
	at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(TransactionResourceImpl.java:348)
	at org.apache.derby.impl.jdbc.EmbedConnection.handleException(EmbedConnection.java:2290)
	at org.apache.derby.impl.jdbc.ConnectionChild.handleException(ConnectionChild.java:82)
	at org.apache.derby.impl.jdbc.EmbedResultSet.closeOnTransactionError(EmbedResultSet.java:4405)
	at org.apache.derby.impl.jdbc.EmbedResultSet.movePosition(EmbedResultSet.java:470)
	at org.apache.derby.impl.jdbc.EmbedResultSet.next(EmbedResultSet.java:374)
	at Test_4544.read(Test_4544.java:41)
	at Test_4544.main(Test_4544.java:18)


> Referencing streaming CLOBs in (some) generated column clauses fails
> --------------------------------------------------------------------
>
>                 Key: DERBY-4544
>                 URL: https://issues.apache.org/jira/browse/DERBY-4544
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.5.3.0, 10.6.1.0
>            Reporter: Kristian Waagan
>            Assignee: Kristian Waagan
>              Labels: CLOB, derby_triage10_8
>         Attachments: Test_4544.java
>
>
> Referencing a CLOB represented as a stream in generated columns can lead to data corruption
or that the query fails.
> For instance, with 10.5:
> create table t (id int, myclob clob, clen generated always as (length(myclob)));
> # Insert CLOB using the streaming APIs (setCharacterStream).
> The exception 'java.lang.ClassCastException: org.apache.derby.iapi.types.ReaderToUTF8Stream
cannot be cast to org.apache.derby.iapi.types.Resetable'
> On trunk the same query results in data corruption, and this isn't detected before the
value is read back from store.
> Workaround:
> Don't use the streaming APIs when using CLOBs in generated columns. This increases the
memory footprint, and may not feasible for large CLOBs.
> FYI, BLOB deals with this by materializing the value, which effectively equals to using
the workaround mentioned above.

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