criteria-api: "cannot perform lookups on timestamps&quo

imario · **Posted:** Sun Jan 30, 2005 10:59 am

Hibernate version:
hiberate3 cvs 2005-01-30

Mapping documents:
annotations

These are the relevant columns of my table:

Code:

public class EventLogDtl implements Serializable {

    @Id(generate = GeneratorType.TABLE)
    @Column(name="w03_number")
    private Long number;

    @Column(name="w03_timestamp")
    private Date timestamp;

...

As you can see I use a surrogating key and a simple timestamp column.

If I try to query this table and set the cacheable flag

Code:

Criteria crit = session.createCriteria(EventLogDtl.class);
crit.setCacheable(true);
crit.add(Expression.ge("timestamp", startDate));
crit.add(Expression.lt("timestamp", endDate));
List events = crit.list();

I get the following exception

Code:

Caused by: java.lang.UnsupportedOperationException: cannot perform lookups on timestamps
        at org.hibernate.type.TimestampType.getHashCode(TimestampType.java:98)
        at org.hibernate.cache.QueryKey.hashCode(QueryKey.java:73)
        at java.util.HashMap.hash(HashMap.java:264)
        at java.util.HashMap.getEntry(HashMap.java:360)
        at java.util.LinkedHashMap.get(LinkedHashMap.java:273)
        at net.sf.ehcache.store.MemoryStore.get(MemoryStore.java:196)
        at net.sf.ehcache.Cache.searchInMemoryStore(Cache.java:523)
        at net.sf.ehcache.Cache.get(Cache.java:358)
        at org.hibernate.cache.EhCache.get(EhCache.java:110)
        at org.hibernate.cache.StandardQueryCache.get(StandardQueryCache.java:74)
        at org.hibernate.loader.Loader.list(Loader.java:1316)
        at org.hibernate.loader.CriteriaLoader.list(CriteriaLoader.java:106)
        at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1603)
        at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:257)

I know, we shouldnt use timestamps as PK-field, but here it is a simple column, but shouldnt it be possible to cache such queries - even if they use timestamps as one of its criterias?

rip_riley · **Joined:** Fri Aug 27, 2004 9:37 am **Posts:** 2

I had (have) the same question.

Although, you can use a org.hibernate.type.CalendarType to cache a query which uses data and time.

imario · **Posted:** Fri Mar 04, 2005 3:05 am

As I am going nuts using javas calander classes I experimented with JODA http://joda-time.sourceforge.net/ and implemented a Hibernate3 UserType for its DateTime class http://l3x.net/imwiki/Wiki.jsp?page=Joda

It looks like this solved it too.

mellster · **Joined:** Fri Apr 15, 2005 7:52 pm **Posts:** 13

Hi,

We have the same issue and for now decided against changing all our existing date mappings to a custom defined type due to time constraints. From our perspective the desired hibernate behavior would be that hibernate ignores the cacheable flag on a query containing a date restriction. It's fine if the user won't get the benefit of caching on these queries, but it should not fail later on on the lookup but instead recover from the attempted lookup and disable caching on the query. That would avoid having to generally setCacheable to false inside the query handling for a centralized db broker class. Any thoughts on this? Thanks