Section 3.1 explains what each of the Activiti tables is used for e.g. what kind of data goes into each table.
3.7. Database table names explained
The database names of Activiti all start withACT_. The second part is a two-character identification of the use case of the table. This use case will also roughly match the service API.
ACT_RE_*:REstands forrepository. Tables with this prefix containstaticinformation such as process definitions and process resources (images, rules, etc.).
ACT_RU_*:RUstands forruntime. These are the runtime tables that contain the runtime data of process instances, user tasks, variables, jobs, etc. Activiti only stores the runtime data during process instance execution, and removes the records when a process instance ends. This keeps the runtime tables small and fast.
ACT_ID_*:IDstands foridentity. These tables contain identity information, such as users, groups, etc.
ACT_HI_*:HIstands forhistory. These are the tables that contain historic data, such as past process instances, variables, tasks, etc.
ACT_GE_*:generaldata, which is used in various use cases.
Perhaps if you describe the use case that you are trying develop that may better explain what you are looking for if the above explanation is not enough.
Once you are familiar with basic engine concepts like process definitions, instances, tasks, etc. and how the data flows, the tables names and columns will become self-explanatory. refer the create script for db definition
TENANT_ID is used when you run engine in multi-tenancy. each tenant will have their own set of process definitions.