Hibernate L2查询缓存：缓存未命中时不要命中数据库

Question

I have a table, Users with primary key id :: int4 and natural key password :: varchar(32) . I'd like to check existence of a row by compund id and password in DB as fast as possible using Hibernate.

So I load all users to L2 cache and do

User u = (User)session.get(User.class, uId);
if (!u.getPassword().equals(pass)) {
   // fail when passwords are not equal
}

This is good when cache was hit, but on cache miss (which means false input data) this will trigger select queries. How can I point hibernate not to hit database, if value not found in cache?

I see an option to load User directly from cache and then use something like session.merge() it. But maybe there is a better way?

PS. I have one more complaint. If passwords are not equal, I have small performance degradation on dehydration of my User object (haven't profiled yet). Can this also be eliminated?

Answer 1

You are using the L2 cache against its intentions: it is always legal for a cache to experience a miss. By its nature the cache does not guarantee to be a 100% replica of an entire table.

If you want a reliable replica of the complete User table, then construct your own HashMap<String,String> .