Summary

The provided content offers an overview of the Camunda process engine's database structure, including table naming conventions, use cases, and instructions for connecting to the database, with a focus on the Camunda BPM Wildfly and Tomcat versions.

Abstract

The web content titled "All about Camunda Database" delves into the database schema of the Camunda process engine as documented in the official Camunda documentation for version 7.19. It explains that the database is composed of tables prefixed with 'ACT_', followed by a two-character identifier indicating the table's purpose, such as repository (RE), runtime (RU), identity (ID), history (HI), and general (GE). The article also guides users through the process of connecting to the database by modifying the standalone.xml file in the Wildfly server configuration, noting that the default database is H2 with credentials 'sa:sa'. It mentions that from Camunda Wildfly version 7.18, access to the H2 console has been discontinued, suggesting the use of tools like Dbeaver for database interaction. The content also touches on the possibility of switching to other databases such as PostgreSQL, MySQL, or MariaDB, and provides examples of how to locate and view process definitions and historical task instances within the database tables. Additionally, the author points readers to further Camunda-related topics and encourages contact for additional information.

Opinions

The author emphasizes the importance of understanding the Camunda database schema for effective use of the process engine.
The article suggests that the Camunda process engine is designed to maintain a lean and efficient runtime environment by only storing runtime data temporarily.
The discontinuation of the H2 console in Camunda Wildfly version 7.18 is presented as a fact, with alternative methods for database access being recommended without expressing a preference for any particular tool.
The author provides a subjective recommendation to use Dbeaver as a database tool, indicating a possible preference or convenience for this software.
By offering a list of related Camunda topics, the author implies that there is a wealth of information available for users who wish to deepen their understanding of Camunda's capabilities and features.

All about Camunda Database

Based on camunda documentation: https://docs.camunda.org/manual/7.19/user-guide/process-engine/database/database-schema/#process-definitions-act-re-procdef

The database structure of the process engine comprises numerous tables.

The table names all begin with ACT.

The second part represents a two-character identifier for the table’s use case.

This use case will also approximately correspond to the service API.

ACT_RE_: RE stands for repository. Tables with this prefix contain ‘static’ data like process definitions and process resources (images, rules, etc.). ACT_RU_: RU stands for runtime. These are the runtime tables holding data on process instances, user tasks, variables, jobs, etc. The engine only stores the runtime data during process instance execution and deletes the records upon process instance termination. This ensures the runtime tables remain small and fast. ACT_ID_: ID stands for identity. These tables contain identity information such as users, groups, etc. ACT_HI_: HI stands for history. These tables store historical data like past process instances, variables, tasks, etc. ACT_GE_*: General data, used across various use cases.

The primary tables of the process engines are the entities for process definitions, executions, tasks, variables, and event subscriptions. Their relationship is depicted in the following UML model.

Let s connect to the database now:

go to this path and open the file standalone.xml:

\camunda-bpm-wildfly-7.18.0\server\wildfly-26.0.1.Final\standalone\configuration\ standalone.xml

then type in the search bar : datasource

as we can see the defaut database is H2 ( in-memory database), the default username and password are sa:sa

it is possible also to change the databse to postgres, mysql, mariadb

from the version 7.18 of wildfly server we don t have access H2 console (based on this documentation : https://docs.camunda.org/manual/7.19/update/minor/717-to-718/#discontinue-camunda-h2-console-web-app

so we can use the tool Dbeaver to connect to database:

for example we can found in the table “ACT_GU_BYTEARRAY” the different deployed process:

and here in table “ACT_HI_TASKINST” the history of task instance:

In the case of camunda tomcat version the configuration of the database exist in the file server.xml:

The full path: camunda-bpm-tomcat-7.18.0\server\apache-tomcat-9.0.58\conf

Thank you for reading this post, Please contact me for any furthers information.