We will see how we can override the default values in upcoming sections. If we look at the datasource.url property, the name of the schema is testdb and is an in-memory database (refered to as "mem"). Since we added H2 as a dependency, Spring Boot knows that in this project we will be connecting to the H2 database, so it auto-configures H2-related properties like the database URL, username, password, etc: = jdbc:h2:mem:testdb = org.h2.Driver = sa = spring.h2.console.enabled= false Spring Boot is an opinionated framework and does all the default configurations based on the dependencies available in the classpath. Understanding H2's Defaults Configurations Make sure to add Web, H2 and JPA (Java Persistence API) dependencies.Īgain, even though H2 typically isn't used as a persistent database - it mocks classical databases, and it interfaces with the Persistence API. The easiest way is to use Spring Initializr and generate a Spring Boot project. Let's start out with a skeleton application. It mocks the functionality and backgone of an actual persistent database, while giving you the ease of use and flexibility of performing queries and "persisting" objects, while still being lightweight.Īlthough H2 does allow you to persist data outside of memory - don't be tempted to replace a more robust database, such as PostgreSQL, MySQL, OracleDB, etc. In-memory databases are helpful for proofs of concept, as you can easily substitute an in-memory database with a persistent one. Once the program is closed, the data is lost. In essence - it's just like using RAM to store your objects. In the case of in-memory databases, data is stored in system memory and data will be lost when the program is closed. Persistent databases persist the data in physical memory - that's the entire point of databases. It is worth understanding the difference between persistent and in-memory databases.
Difference Between Persistent and In-Memory Databases The H2 database is not recommended for production environments and is rather used for proofs of concept, tests, prototypes and similar applications. Although if we need to persist the data, at the flick of a switch - you can persist data as well. Typically, it's used as an in-memory database which means it stores the data in memory and will not persist data on disk. H2 is an open-source, Java-based, embedded database.
#H2 DATABASE HOW TO#
In this guide, we'll take a look at how to integrate the H2 database with Spring Boot projects.
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