Purge old events in histoty Zenoss table

Hello,

we use Zenoss :

Zenoss : Zenoss 3.1.0
OS : CentOS release 5.6 (Final)
Zope : Zope 2.12.1
Python : Python 2.6.2
Database : MySQL 5.0.77 (Ver 5.0.77)
RRD : RRDtool 1.3.9
Twisted : Twisted 8.1.0
NetSnmp : NetSnmp 5.3.2
PyNetSnmp : PyNetSnmp 0.28.14
WMI : Wmi 1.3.13

We need to purge zenoss events BDD in the history table, note that the history table makes 15Go and we have no free space in the VM to dump MySQL BDD.

We tried to purge events with ZenDeleteHistory.py but the script does not clean/purge events

./ZenDeleteHistory.py --numDays=90

we tried too to purge events with SQL command with "Where" condition for make this easier :

SELECT * FROM history WHERE stateChange >= '2014-01-01' AND stateChange <= '2014-12-01';

but we have always the same problem.

Can you help please.

Regards,