lower() DB function renders idex on LSW_BPD_INSTANCE ineffective

Description of the issue; we started seeing “SQLCODE=-905, SQLSTATE=57014”. At that time, process instance creation was successful but all fetch operation failed. See ticket number - TS002094734; this ticket number failed the PMR validation above.

[3/28/19 15:57:10:482 EDT] 0000dedf ProgrammaticT W CWLLG2103W: The retry limit of 5 was exceeded in ProgrammaticTransactionSupport.
[3/28/19 15:57:10:483 EDT] 0000dedf wle E CWLLG2229E: An exception occurred in an EJB call. Error: PreparedStatementCallback; SQL [
SELECT i.EXECUTION_STATUS, COUNT(*) AS INSTANCE_COUNT
FROM LSW_BPD_INSTANCE i
WHERE LAST_MODIFIED_DATETIME<=? AND
(lower(i.INSTANCE_NAME) LIKE ? ESCAPE '\')
GROUP BY i.EXECUTION_STATUS
WITH UR
]; DB2 SQL Error: SQLCODE=-905, SQLSTATE=57014, SQLERRMC=ASUTIME;000000000007;000000500000;SYSTEM PARAMETER, DRIVER=4.21.29; nested exception is com.ibm.db2.jcc.am.SqlException: DB2 SQL Error: SQLCODE=-905, SQLSTATE=57014, SQLERRMC=ASUTIME;000000000007;000000500000;SYSTEM PARAMETER, DRIVER=4.21.29
org.springframework.dao.DataAccessResourceFailureException: PreparedStatementCallback; SQL [
SELECT i.EXECUTION_STATUS, COUNT(*) AS INSTANCE_COUNT
FROM LSW_BPD_INSTANCE i
WHERE LAST_MODIFIED_DATETIME<=? AND
(lower(i.INSTANCE_NAME) LIKE ? ESCAPE '\')

GROUP BY i.EXECUTION_STATUS
WITH UR
]; DB2 SQL Error: SQLCODE=-905, SQLSTATE=57014, SQLERRMC=ASUTIME;000000000007;000000500000;SYSTEM PARAMETER, DRIVER=4.21.29; nested exception is com.ibm.db2.jcc.am.SqlException: DB2 SQL Error: SQLCODE=-905, SQLSTATE=57014, SQLERRMC=ASUTIME;000000000007;000000500000;SYSTEM PARAMETER, DRIVER=4.21.29
at org.springframework.jdbc.support.SQLStateSQLExceptionTranslator.doTranslate(SQLStateSQLExceptionTranslator.java:105)
.
.
.
[3/28/19 15:57:10:485 EDT] 0000dedf RestHelper W Unexpected database exception
com.lombardisoftware.core.TeamWorksException: Unexpected database exception
at com.ibm.bpm.rest.util.RestHelper.getExceptionResponse(RestHelper.java:473)
at com.ibm.bpm.rest.util.RestHelper.getExceptionResponse(RestHelper.java:444)
at com.ibm.bpm.rest.impl.process.ProcessesResource.getProcessInstances(ProcessesResource.java:1579)
at sun.reflect.GeneratedMethodAccessor935.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:508)

Workaround:
Up DB2 SQL CPU allotment from 7 seconds to 32 seconds. The above query now runs within 32 seconds but that is not acceptable.

Recommendation By DB2 DBA:

I would get them to fix the app so the lower() function wasn't necessary.
Barring that, add column function to the table and place that column in an index. Expression on index became available in db2 v10.
Create index xxxxx on LSW_BPD_INSTANCE (LAST_MODIFIED_DATETIME, lower(i.INSTANCE_NAME, execution_status)
So this would be my recommendation for ibm to add to the product.
SELECT i.EXECUTION_STATUS, COUNT(*) AS INSTANCE_COUNT
FROM LSW_BPD_INSTANCE i
WHERE LAST_MODIFIED_DATETIME<=? AND
(lower(i.INSTANCE_NAME) LIKE ? ESCAPE '\')
GROUP BY i.EXECUTION_STATUS