CODEWITHSUNDEEP
mysqlhibernatejpahikaricp
Justin
Justin

Reputation: 6251

Why is 'SHOW WARNINGS' query issued here? (JPA/Hibernate/MySQL)

We are refactoring the persistence layer of a Java application from JDBC Template to JPA/Hibernate.

I am profiling the SQL statements being issued to the database and I see "SHOW WARNINGS" is issued many, many times. According to JProfiler the "SHOW WARNINGS" is accounting for a considerable amount of 'inherent time'.

What could cause SHOW WARNINGS to be issued so frequently?

This SHOW WARNINGS was NOT previously issued when using Jdbc Template.

Below is the part of our stack relevant to persistence. The only change here is the introduction of JPA/Hibernate.

EDIT: Here's a sample stack trace of when SHOW WARNINGS is issued.

com.mysql.jdbc.StatementImpl.getWarnings()
com.zaxxer.hikari.proxy.PreparedStatementJavassistProxy.getWarnings()
org.hibernate.jpa.internal.QueryImpl.getSingleResult()
com.mysema.query.jpa.impl.AbstractJPAQuery.getSingleResult(javax.persistence.Query)
com.mysema.query.jpa.impl.AbstractJPAQuery.uniqueResult()
com.mysema.query.jpa.impl.AbstractJPAQuery.uniqueResult(com.mysema.query.types.Expression)
org.springframework.aop.framework.JdkDynamicAopProxy.invoke(java.lang.Object, java.lang.reflect.Method, java.lang.Object[ ])
com.sun.proxy.$Proxy115.findOne(com.mysema.query.types.Predicate)

Upvotes: 6

Views: 4520

Answers (2)

Tomaž Majerhold
Tomaž Majerhold

Reputation: 145

Nothing of this works on payara & log4j, hibernate is still polluting DB with 'show warnings' statements

Upvotes: 0

Justin
Justin

Reputation: 6251

This is WHY show warnings is being issued: org.hibernate.engine.jdbc.spi.SqlExceptionHelper.handleAndClearWarnings() is calling com.mysql.jdbc.StatementImpl.getWarnings().

A comment in the Hibernate source code says:

"See HHH-9174. Statement#getWarnings can be an expensive call for many JDBC libs. Don't do it unless the log level would actually allow a warning to be logged."

I upped the logging level on logback.xml on "org.hibernate" to ERROR. Profiling shows SHOW WARNINGS query is NO LONGER being issued.

This has made a marginal improvement in performance.

I would appreciate any input as to whether it is actually a good idea to disable SHOW WARNINGS here.

Upvotes: 10

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