Exception "inconsistent datatypes" on VisitStats in Oracle 10g

There is a problem with field XWV_COOKIE in table XWIKISTATSVISIT. It throws an exception about "inconsistent datatypes" - see error stack below.
I've found JIRA:XASTATS-12 in UNRESOLVED state, so it's an already reported problem. Maybe someone can still take a look...

The original field-type in database is CLOB.
In xwiki.hdm.xml (xwiki-core-1.8.jar) the field is declared as:
<property name="cookie" type="string">
<column name="XWV_COOKIE" not-null="true" length="8192"/>
</property>

Workaround:
I've dropped the field and recreated it as VARCHAR(2000) in database. The exception is gone - but i don't have the knowledge in hibernate or the application to contribute to the problem solution.

Error Stack:
11:58:03,601 WARN [JDBCExceptionReporter] SQL Error: 932, SQLState: 42000
11:58:03,601 ERROR [JDBCExceptionReporter] ORA-00932: inconsistent datatypes: expected - got CLOB
11:58:03,601 ERROR [StatsUtil] Failed to search visit object in the database from cookie
org.xwiki.query.QueryException: Exception while execute query. Query statement = [from VisitStats as obj where obj.cookie=:fieldValue and obj.endDate > :date order by obj.endDate desc]
at com.xpn.xwiki.store.hibernate.query.HqlQueryExecutor.execute(HqlQueryExecutor.java:93)
at org.xwiki.query.internal.DefaultQueryExecutorManager.execute(DefaultQueryExecutorManager.java:56)
at org.xwiki.query.internal.DefaultQuery.execute(DefaultQuery.java:230)
at com.xpn.xwiki.stats.impl.StatsUtil.findVisitByField(StatsUtil.java:526)
at com.xpn.xwiki.stats.impl.StatsUtil.findVisitByCookie(StatsUtil.java:551)
at com.xpn.xwiki.stats.impl.StatsUtil.findVisitByCookieOrIPUA(StatsUtil.java:385)
at com.xpn.xwiki.stats.impl.StatsUtil.findVisit(StatsUtil.java:330)
at com.xpn.xwiki.stats.impl.xwiki.XWikiStatsStoreService.addStats(XWikiStatsStoreService.java:195)
at com.xpn.xwiki.stats.impl.XWikiStatsServiceImpl.notify(XWikiStatsServiceImpl.java:147)
at com.xpn.xwiki.notify.XWikiActionRule.verify(XWikiActionRule.java:62)
at com.xpn.xwiki.notify.XWikiNotificationManager.verify(XWikiNotificationManager.java:245)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:311)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:115)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.xpn.xwiki.wysiwyg.server.filter.ConversionFilter.doFilter(ConversionFilter.java:145)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:111)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.xpn.xwiki.plugin.webdav.XWikiDavFilter.doFilter(XWikiDavFilter.java:68)
...