Ayende @ Rahien

Ayende Rahien commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 11 Jun 2009 13:23:15 GMT

James, Yes

James Spibey commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 11 Jun 2009 12:54:16 GMT

Is there a way to tell NHibernate to cache an entire table the first time any entity is loaded from it? I often use a series of small lookup tables which my entities reference and it would make sense to load the entire lookup table rather than query the DB for each value

RichB commented on NHibernate – Beware of inadvisably applied caching strategies

Fri, 05 Jun 2009 14:00:30 GMT

Ooops. Sorry. I'm still learning.

Ayende Rahien commented on NHibernate – Beware of inadvisably applied caching strategies

Fri, 05 Jun 2009 13:08:32 GMT

RichB, What I am talking about here is the _2nd_ level cache

Gunnar Liljas commented on NHibernate – Beware of inadvisably applied caching strategies

Fri, 05 Jun 2009 12:48:36 GMT

The session cache is not the same thing as this (2nd level cache)

RichB commented on NHibernate – Beware of inadvisably applied caching strategies

Fri, 05 Jun 2009 12:26:35 GMT

NHibernate in Action (pg156) says: > You don't have to do anything special to enable the session cache. It's always on and, for the reasons shown, can't be turned off. WTF?

Ayende Rahien commented on NHibernate – Beware of inadvisably applied caching strategies

Fri, 05 Jun 2009 11:54:46 GMT

Michael, Either don't use caching, or cache Post. See my reply to Cassio for the reasoning behind that decision

Ayende Rahien commented on NHibernate – Beware of inadvisably applied caching strategies

Fri, 05 Jun 2009 11:53:02 GMT

Cassio, That depends on your scenario, I can't really tell. Enabling cache on Post would be easiest, but is it cachable? For how long? If it drops out of the cache, you are back to the same problem. That is why this is sensitive to context.

Ayende Rahien commented on NHibernate – Beware of inadvisably applied caching strategies

Fri, 05 Jun 2009 11:51:32 GMT

iocer, You need to cache the entities as well

Gunnar Liljas commented on NHibernate – Beware of inadvisably applied caching strategies

Fri, 05 Jun 2009 08:26:06 GMT

In theory I guess it would be possible for NHibernate to make an informed decision whether to load from cache or not.

iocer commented on NHibernate – Beware of inadvisably applied caching strategies

Fri, 05 Jun 2009 08:23:18 GMT

So how do we cache data instead of ids with NH ?

Cassio Tavares commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 22:52:17 GMT

But you didn't put the

Michael Teper commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 19:30:18 GMT

So in the example you outlined, what would be the solution?

Miki Watts commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 17:37:50 GMT

Ah, excellent, thanks. Though, what if I don't know the IDs of what I want and i need to query for them? Would I call FindByPrimaryKey on each one of them afterwards so it'll store the id ?

Ayende Rahien commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 10:51:57 GMT

Miki, FindByPrimaryKey translate to that, and calling it with true or false will render the appropriate get/load call. And you just load the collection

Miki Watts commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 06:18:21 GMT

Thanks, Ayende, I finally understood how Get/Load works and its effects on the second level cache. But if I'm using ActiveRecord, and I don't usually have access to the Session, how do I load entities with ActiveRecord so that they'll go into the second level cache ? Also, how do I put a collection of entities into the second cache all at once, without having select n+1 ?

CaliCoder commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 03:56:22 GMT

Sign me up

Ayende Rahien commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 01:54:48 GMT

Dmitry, You would be surprised how much a 5 min cache can help to app perf. And yes, there is such a thing, SysCache2 can understand SqlDependencies.

Ayende Rahien commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 01:53:59 GMT

Cali, NH Prof _IS_ Hibernate Compatible. Would you like to take part in the private beta?

Dmitry commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 00:47:12 GMT

The only time I'm using second level cache for entities _and_ collections that rarely/never change like customer types or countries. Caching queries or collections of entities that change frequently is likely to cause more issues than it solves. Is there a cache in NHibernate that works with MS SQL notifications?

CaliCoder commented on NHibernate – Beware of inadvisably applied caching strategies

Thu, 04 Jun 2009 00:16:11 GMT

I haven't tried your app yet since it's not Hibernate compatible, but if it analyzes these types of situations and warns us mere mortals of the traps then "NH Profiler is your friend" is what the people will say