Understanding the default database tables
The Pega Platform contains database table ( Data-Admin-DB-Table ) data instances when it is initially installed. These instances are linked to various database tables and views in the Pega database, and are used to map classes or class groups to database tables or views.
To view the databases, database tables, and database indexes in your system, click.
The following list of Pega Platform database tables provides more information about each of the initial table types.
- Database tables
Create database table data instances to map classes or class groups to database tables or views. You can use the Database Table form to revise existing class-to-table relationships.
- Assignment tables
Assignments are instances of a concrete class derived from the Assign- base class. A newly installed system does not contain any assignments. As work items progress, the system creates and deletes assignments. Assignments may exist only for a few seconds, or for days or months.
- Case tables
Cases are the primary units of processing in applications that use flows. A large fraction of database processing involves creating and updating cases. Updates to related objects, such as assignments and attachments, usually also require updates to the case.
- Data object tables
The initial Pega Platform database schema has database tables that contain rows corresponding to instances of concrete Data- classes.
- History tables
The Pega Platform database tables that initially contain history instances are insert-only tables. New rows are added but existing rows are not ordinarily deleted or updated.
- Index tables
Instances of concrete classes derived from the Index- base class support reporting and rapid data access. Such instances are created and deleted by Declare Index rules. For example, the pr-index-assignmentdeps contains rows that correspond to instances of the Index-AssignmentDep class, which supports dependent assignment processing.
- Link tables
Link tables store information about paired object instances in your system. For example, the pc_link_attachment table supports the association of a work item attachment with a work item, as instances of the Link-Attachment class, and contains one row for each attachment.
- Log tables
The following Pega Platform database tables can store instances of Log- classes. For example, the pr_changelog table holds instances of the concrete classes derived from Log-System-. They record schema changes made using the Property Optimization tool and the Modify Schema tab.
- pr_other table
The pr_other table is the default destination for saved instances that belong to a class that is not mapped to any other table. To access the pr_other table, the system uses the catalog and schema specified for the pr4_base table as identified in the databases/baseTable/catalog and databases/baseTable/schema entries in the prconfig.xml file or dynamic system settings.
- Rules tables
Rule instances in the Pega Platform database are heavily indexed to speed the searching operations used in rule resolution.
- System tables
In the initial Pega Platform database schema, certain database tables contain instances of concrete classes derived from the System- base class.
- Work item history types
As a work item progresses through one or more flows in your system, the system automatically appends instances to the work item history, recording the date, time, operator, and other facts about the progress. The history type of a history instance for a work item identifies the event that corresponds to the instance.
- Work item reports
Standard reports on work items are based on the exposed columns in the schema of the pc_work table for work items, and the pc_history_work table for history instances for work items.