This problem is not consistent in that it can happen on any source, the number of queries vary, and it eventually goes away with enough executions. I am not sure what is triggering the problem.

As an example I ran the full query suite against Ora11, Ora10, SqlSer2008 in a single test execution and each of them received 41 failures
because the exception error message changed. I then immediately reran the test and this time Ora11, Ora10 and SqlSer2008 all passed but MySql51 had 32 of the same type of failure. I reran the same test a 3rd time and this time everything passed. This has only happened on RHEL6.

Below is an example of one of the failing queries in the latest MySql run. This example has the actual exception from the run and the expected exception. I have also included the exception from the server log and it matches the expected exception.

<?xml version="1.0" encoding="UTF-8"?>
<root>
<queryResults name="RDBMS_Test_Queries_9000_TestQuery255" value="SELECT BQT1.MediumA.ByteNum, BQT2.MediumB.ObjectValue FROM BQT1.MediumA, BQT2.MediumB WHERE BQT1.MediumA.ByteNum = convert(BQT2.MediumB.ObjectValue, byte) AND (BQT1.MediumA.IntKey >= 0 AND BQT1.MediumA.IntKey < 256) AND (BQT2.MediumB.IntKey >= 0 AND BQT2.MediumB.IntKey < 256) ORDER BY BQT1.MediumA.ByteNum">

THIS IS THE ACTUAL EXCEPTION:
<actual_exception>
<exceptionType>TeiidSQLException</exceptionType>
<message>Error trying to execute a statement SELECT BQT1.MediumA.ByteNum, BQT2.MediumB.ObjectValue FROM BQT1.MediumA, BQT2.MediumB WHERE BQT1.MediumA.ByteNum = convert(BQT2.MediumB.ObjectValue, byte) AND (BQT1.MediumA.IntKey >= 0 AND BQT1.MediumA.IntKey < 256) AND (BQT2.MediumB.IntKey >= 0 AND BQT2.MediumB.IntKey < 256) ORDER BY BQT1.MediumA.ByteNum.</message>
<class>org.teiid.jdbc.TeiidSQLException</class>
</actual_exception>

THIS IS THE EXPECTED EXCEPTION
<expected_exception>
<exceptionType>TeiidSQLException</exceptionType>
<message>Error Code:ERR.015.001.0003 Message:Unable to evaluate convert(convert(Source.MEDIUMB.OBJECTVALUE, object), byte): Error Code:ERR.015.001.0003 Message:
Error while evaluating function convert</message>
<class>org.teiid.jdbc.TeiidSQLException</class>
</expected_exception>
</queryResults>
</root>

THIS IS THE EXCEPTION AS STATED IN THE SERVER LOG WHICH MATCHES THE EXPECTED EXCEPTION
2011-01-28 11:17:52,779 WARN [org.teiid.PROCESSOR] (Worker0_QueryProcessorQueue157992) Processing exception 'Error Code:ERR.015.001.0003 Message:Unable to evaluate convert(convert(Source.MediumB.ObjectValue, object), byte): Error Code:ERR.015.001.0003 Message:Error while evaluating function convert' for request tnuf/C2ODO8c.2685. Exception type org.teiid.api.exception.query.ExpressionEvaluationException thrown from org.teiid.core.types.basic.StringToByteTransform.transformDirect(StringToByteTransform.java:43). Enable more detailed logging to see the entire stacktrace.