Add support for per-query metrics in Hibernate statistics

[jfougere]

Current implementation of HibernateMetrics exposed counters & also time gauges for max execution queries, however no tags are provided in order to know about which query those metrics are related.

I believe this could be very useful and could be done using current Hibernate Statistics class implementation.

For example the TimeGauge hibernate.query.executions.max could be tag with a query tag and the value could be provided by Statistics.getQueryExecutionMaxTimeQueryString().

Also the other counter metrics could be retrieved by query using:

• Statistics.getQueries()
• Statistics.getQueryStatistics(String query)

What do u think ?

[jkschneider]

Sounds great. A PR would be welcome!

[chrisatrotter]

Could you provide an example of how to use the per-query metric support in Hibernate statistics? I've tried to find out how to have this functionality work with Spring boot through the spring-actuator to expose hibernate statistics with per-query metrics. I've had little success until i found this great change! 🙌

[shakuzen]

Note that Hibernate metrics have moved to the Hibernate project, in the hibernate-micrometer module.

You need to enable statistics for Hibernate by setting the hibernate.generate_statistics configuration to true, which can be done with Spring Boot application properties like spring.jpa.properties.hibernate.generate_statistics=true. See the Spring Boot documentation. You will need to provide an instance of HibernateQueryMetrics as a bean or bind it yourself, since Spring Boot does not currently auto-configure it. You can do that in a @Configuration class, for example, like the following:

@Bean
MeterBinder hibernateQueryMetrics(EntityManagerFactory entityManager) {
    return new HibernateQueryMetrics(entityManager.unwrap(SessionFactoryImplementor.class), "mySess", Tags.empty());
}