1

问题：

我有一个条件查询，其中使用了 Hibernate 的二级缓存cache(true)：

User user = User.createCriteria().get {
    eq("id", 1l)
    cache(true)
}

当此代码被命中两次时，第一次它会进行预期的数据库查询，但是当下次执行相同的代码时，它不应该命中数据库以进行查询，而是应该从缓存中获取它。但这并没有发生。

日志：

2019-08-29 23:25:06.023 DEBUG --- [nio-8080-exec-1] o.h.cache.internal.StandardQueryCache    : Checking cached query results in region: org.hibernate.cache.internal.StandardQueryCache
2019-08-29 23:25:06.023 DEBUG --- [nio-8080-exec-1] o.h.c.e.i.r.EhcacheGeneralDataRegion     : key: sql: select this_.id as id1_0_0_, this_.version as version2_0_0_, this_.first_name as first_na3_0_0_, this_.last_name as last_nam4_0_0_, this_.email as email5_0_0_ from user this_ where this_.id=?; parameters: 1, ; transformer: org.hibernate.transform.CacheableResultTransformer@110f2
2019-08-29 23:25:06.027 DEBUG --- [nio-8080-exec-1] o.h.c.e.i.r.EhcacheGeneralDataRegion     : Element for key sql: select this_.id as id1_0_0_, this_.version as version2_0_0_, this_.first_name as first_na3_0_0_, this_.last_name as last_nam4_0_0_, this_.email as email5_0_0_ from user this_ where this_.id=?; parameters: 1, ; transformer: org.hibernate.transform.CacheableResultTransformer@110f2 is null
2019-08-29 23:25:06.028 DEBUG --- [nio-8080-exec-1] o.h.cache.internal.StandardQueryCache    : Query results were not found in cache
2019-08-29 23:25:06.030 DEBUG --- [nio-8080-exec-1] org.hibernate.SQL                        : select this_.id as id1_0_0_, this_.version as version2_0_0_, this_.first_name as first_na3_0_0_, this_.last_name as last_nam4_0_0_, this_.email as email5_0_0_ from user this_ where this_.id=?
2019-08-29 23:25:06.046 DEBUG --- [nio-8080-exec-1] o.h.s.internal.ConcurrentStatisticsImpl  : HHH000117: HQL: [CRITERIA] select this_.id as id1_0_0_, this_.version as version2_0_0_, this_.first_name as first_na3_0_0_, this_.last_name as last_nam4_0_0_, this_.email as email5_0_0_ from user this_ where this_.id=?, time: 17ms, rows: 1
2019-08-29 23:25:06.047 DEBUG --- [nio-8080-exec-1] o.h.cache.internal.StandardQueryCache    : Caching query results in region: org.hibernate.cache.internal.StandardQueryCache; timestamp=6418846948913152
2019-08-29 23:25:06.049 DEBUG --- [nio-8080-exec-1] o.h.c.e.i.r.EhcacheGeneralDataRegion     : key: sql: select this_.id as id1_0_0_, this_.version as version2_0_0_, this_.first_name as first_na3_0_0_, this_.last_name as last_nam4_0_0_, this_.email as email5_0_0_ from user this_ where this_.id=?; parameters: 1, ; transformer: org.hibernate.transform.CacheableResultTransformer@110f2 value: [6418846948913152, 1]
Found com.wizpanda.test.User : 1
2019-08-29 23:25:06.099  INFO --- [nio-8080-exec-1] i.StatisticalLoggingSessionEventListener : Session Metrics {
    45071 nanoseconds spent acquiring 1 JDBC connections;
    0 nanoseconds spent releasing 0 JDBC connections;
    3767346 nanoseconds spent preparing 1 JDBC statements;
    4620558 nanoseconds spent executing 1 JDBC statements;
    0 nanoseconds spent executing 0 JDBC batches;
    7925151 nanoseconds spent performing 1 L2C puts;
    0 nanoseconds spent performing 0 L2C hits;
    4562453 nanoseconds spent performing 1 L2C misses;
    0 nanoseconds spent executing 0 flushes (flushing a total of 0 entities and 0 collections);
    0 nanoseconds spent executing 0 partial-flushes (flushing a total of 0 entities and 0 collections)
}

环境：

  • 操作系统：MacOS、CentOS7
  • GORM 版本： 6.1.11
  • Grails 版本（如果使用 Grails）： 3.3.9
  • JDK版本： 1.8.0_91

重现步骤：

  1. 克隆这个repo git clone git@github.com:wizpanda/test-l2-cache.git
  2. 登录 MySQL 数据库并创建一个新数据库create database test_l2_cache
  3. 更改 MySQL 用户名和密码grails-app/conf/application.yml
  4. 运行应用程序grails run-app或./gradlew bootRun
  5. 浏览http://localhost:8080/并检查日志

提出的问题：https ://github.com/grails/grails-data-mapping/issues/1266

4

1 回答 1

1

第一步，您需要启用 Hibernate 的二级缓存，如下所示：

hibernate.cache.use_second_level_cache=true

这样，您只为实体而不是查询启用了二级缓存。

如果您需要在查询/条件级别缓存：

在休眠 API 中：query.setCacheable(true); //query is instance of org.hibernate.Query

在 JPA 中：query.setHint("org.hibernate.cacheable", true) //query is instance of javax.persistence.Query

于 2019-10-23T12:35:36.290 回答