SQL Components as Instance Variables

You can use cataloged SQL table components as process instance variables. This is useful when you want to persist data associated with a process instance into a separate database.

Unlike any other component types, the Process Execution Engine treats process instance variables of a SQL table component type in a special way.

When the Engine completes the execution of a transaction on a process instance (most commonly, the execution of a process activity) the Engine persists the state of all instance variables on its runtime database. However, for those instance variables of a SQL table component type, the Engine only persists its primary key attributes.

When you access the attributes of a SQL table object used as instance variable, the component automatically loads its attributes from the database. Refer to Using SQL Components for details on how SQL components are auto-loaded.

This special behavior for SQL table components provides the following benefits:

Prevents unnecessary duplication of information. Since you do not keep the information separately from the original database, you always access the latest updated information.
The SQL component is auto-loaded on demand. The component does not query the database until your code sets or reads one of its attributes.
Reduces the size of your process instances payload. This not only saves storage space but also improves process execution performance.

Disabling special handling of SQL components

You can disable this behavior by setting the accessDatabase attribute of the component to false.

When attribute accessDatabase is false on a SQL component used as a process instance variable, the Process Execution Engine persists the complete state of the variable, including all primary key and non-primary key attributes.

When attribute accessDatabase to false, auto-loading is disabled. Refer to Using SQL Components for details on how SQL components are auto-loaded.

  // "customer" is a process instance variable of
  // SQL table type "CUSTOMER"
  this.customer.accessDatabase = false

  //... from now own, the Engine stores the complete state of
  // "customer" variable, including non-primary key fields.
  // Auto-loading is also disabled for this variable.