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https://issues.apache.org/jira/browse/OPENJPA-2745?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16573498#comment-16573498
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ASF subversion and git services commented on OPENJPA-2745:
----------------------------------------------------------
Commit 1837661 from dazey...@apache.org in branch 'openjpa/branches/2.4.x'
[ https://svn.apache.org/r1837661 ]
OPENJPA-2745: Clean up try-catch implementation for DB2Dictionary
> Clean up try-catch implementation for DB2Dictionary
> ---------------------------------------------------
>
> Key: OPENJPA-2745
> URL: https://issues.apache.org/jira/browse/OPENJPA-2745
> Project: OpenJPA
> Issue Type: Improvement
> Reporter: Will Dazey
> Assignee: Will Dazey
> Priority: Minor
> Fix For: 2.2.0, 2.3.0, 2.4.0, 3.0.0
>
> Attachments: DB2Dictionary.patch
>
>
> On IBM WebSphere Server, which currently ships OpenJPA as our JPA 2.0
> implementation provider, we are seeing the following FFDC exception:
> {code:java}
> FFDC Exception:com.ibm.db2.jcc.am.SqlSyntaxErrorException
> SourceId:com.ibm.ws.rsadapter.jdbc.WSJdbcResultSet.getBlob ProbeId:754
> Reporter:com.ibm.ws.rsadapter.jdbc.WSJccResultSet@a35b6d30
> com.ibm.db2.jcc.am.SqlSyntaxErrorException: [jcc][t4][1092][11643][4.19.49]
> Invalid data conversion: Wrong result column type for requested conversion.
> ERRORCODE=-4461, SQLSTATE=42815
> at com.ibm.db2.jcc.am.kd.a(Unknown Source)
> at com.ibm.db2.jcc.am.kd.a(Unknown Source)
> at com.ibm.db2.jcc.am.kd.a(Unknown Source)
> at com.ibm.db2.jcc.am.mc.V(Unknown Source)
> at com.ibm.db2.jcc.am.ResultSet.getBlob(Unknown Source)
> at
> com.ibm.ws.rsadapter.jdbc.WSJdbcResultSet.getBlob(WSJdbcResultSet.java:739)
> at
> org.apache.openjpa.lib.jdbc.DelegatingResultSet.getBlob(DelegatingResultSet.java:588)
> at
> org.apache.openjpa.jdbc.sql.DBDictionary.getBlob(DBDictionary.java:667)
> at
> org.apache.openjpa.jdbc.sql.DB2Dictionary.getBytes(DB2Dictionary.java:1032)
> at
> org.apache.openjpa.jdbc.sql.ResultSetResult.getBytesInternal(ResultSetResult.java:290)
> at
> org.apache.openjpa.jdbc.sql.ResultSetResult.getObjectInternal(ResultSetResult.java:425)
> {code}
> The reason for this exception is due to the implementation of
> org.apache.openjpa.jdbc.sql.DB2Dictionary.getBytes(ResultSet rs, int column):
> {code:java}
> // At this point we don't have any idea if the DB2 column was defined
> as
> // a blob or if it was defined as CHAR for BIT DATA.
> // First try as a blob, if that doesn't work, then try as CHAR for
> BIT DATA
> // If that doesn't work, then go ahead and throw the first exception
> try {
> Blob blob = getBlob(rs, column);
> if (blob == null) {
> return null;
> }
>
> int length = (int) blob.length();
> if (length == 0) {
> return null;
> }
>
> return blob.getBytes(1, length);
> }
> catch (SQLException e) {
> try {
> return rs.getBytes(column);
> }
> catch (SQLException e2) {
> throw e;
> }
> }
> {code}
> With this implementation, if getBlob() throws an SQLException, then we
> attempt rs.getBytes(). However, on WebSphere, the exception has already been
> thrown and logged, regardless if getBytes() will end up working. This causes
> false FFDC exceptions for us. A better implementation would be to make the
> decision based on the column type and not a random guess-check.
> The thing is, the current implementation still works, but is not written in
> with the best performance. This change is just to streamline the
> implementation and shy away from the try-catch pattern. I am not including a
> test since existing tests should be sufficient to make sure this
> implementation doesnt change behavior.
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