4.3.3. The Execution of Database Scripts by Gradle Tasks

This mechanism is generally used by application developers for updating their own database instance. The execution of scripts essentially comes down to running a special Gradle task from build.gradle build script. This can be done from the command line or via the Studio interface.

To run scripts to create the database, the createDb task is used. In Studio, it corresponds to the Run → Create database command in main menu. When this task is started, the following occurs:

  1. Scripts of the application components and db/**/*.sql scripts of the core module of the current project are built in the modules/core/build/db directory. Sets of scripts for application components are located in subdirectories with numeric prefixes. The prefixes are used to provide the alphabetical order of the execution of scripts according to the dependencies between components.

  2. If the database exists, it is completely erased. A new empty database is created.

  3. All creation scripts from modules/core/build/db/init/**/*create-db.sql subdirectory are executed sequentially in the alphabetical order, and their names along with the path relative to the db directory are registered in the SYS_DB_CHANGELOG table.

  4. Similarly, in the SYS_DB_CHANGELOG table, all currently available modules/core/build/db/update/**/*.sql update scripts are registered. This is required for applying the future incremental updates to the database.

To run scripts to update the database, the updateDb task is used. In Studio, it corresponds to the Run → Update database command in main menu. When this task is started, the following occurs:

  1. The scripts are built in the same way as for the createDb command described above.

  2. The execution mechanism checks, whether all creation scripts of application components have been run (by checking the SYS_DB_CHANGELOG table). If not, the application component creation scripts are executed and registered in the SYS_DB_CHANGELOG table.

  3. A search is performed in modules/core/build/db/update/** directories, for update scripts which are not registered in the SYS_DB_CHANGELOG table, i.e., not previously executed.

  4. All scripts found in the previous step are executed sequentially in the alphabetical order, and their names along with the path relative to the db directory are registered in the SYS_DB_CHANGELOG table.