1. Overview
Spring JDBC and JPA provide abstractions over native JDBC APIs allowing developers to do away with native SQL queries. However, often we need to see those auto-generated SQL queries and the order in which they were executed for debugging purposes.
In this quick tutorial, we’re going to look at different ways of logging these SQL queries in Spring Boot.
2. Logging JPA Queries
2.1. To Standard Output
The simplest way is to dump the queries to standard out is to add the following to application.properties:
spring.jpa.show-sql=true
To beautify or pretty print the SQL, we can add:
spring.jpa.properties.hibernate.format_sql=true
While this is extremely simple, it’s not recommended as it directly unloads everything to standard output without any optimizations of a logging framework.
Moreover, it doesn’t log the parameters of prepared statements.
2.2. Via Loggers
Now, let’s see how we can log the SQL statements by configuring loggers in the properties file:
logging.level.org.hibernate.SQL=DEBUG logging.level.org.hibernate.type.descriptor.sql.BasicBinder=TRACE
The first line logs the SQL queries, and the second statement logs the prepared statement parameters.
The pretty print property will work in this configuration as well.
By setting these properties, logs will be sent to the configured appender. By default, Spring Boot uses logback with a standard out appender.
3. Logging JdbcTemplate Queries
To configure statement logging when using JdbcTemplate, we need the following properties:
logging.level.org.springframework.jdbc.core.JdbcTemplate=DEBUG logging.level.org.springframework.jdbc.core.StatementCreatorUtils=TRACE
Similar to the JPA logging configuration, the first line is for logging statements and the second one is to log parameters of prepared statements.
4. How Does it Work?
The Spring / Hibernate classes, which generate SQL statements and set the parameters, already contain the code for logging them.
However, the level of those log statements is set to DEBUG and TRACE respectively, which is lower than the default level in Spring Boot – INFO.
By adding these properties, we are just setting those loggers to the required level.
5. Conclusion
In this short article, we’ve looked at the ways to log SQL queries in Spring Boot.
If we choose to configure multiple appenders, we can also separate SQL statements and other log statements into different log files to keep things clean.