PostgreSQL® Schema
Note: When using NextGen Archiver with
PostgreSQL® or MS SQL®, data point elements of type ulong, long or bit64 are limited
to 53 bit precision.
The PostgreSQL® database schema contains several tables:
- systems – contains information of the systems of the WinCC OA project.
- elements – contains information of the data point elements that must read/write/archive their values.
- archive_groups – contains archive groups of the backend.
- elements_to_archive_groups – defines relations (many-to-many) between "archive groups" and "elements". This table allows storing crossing for multiple archive groups.
- segments – stores segments of archive groups.
- _event_%segment_id%_a – stores simple (non-dyn) EVENTS values.
- _events_%segment_id%_d – stores events for dyn values.
- _alert_%segment_id%_a – stores ALARM values.
- _alert_%segment_id%_add – stores additional values for ALARMS.
- configuration – is used as a key-value storage of internal parameters, which are defined when the DB is created.
- scheduler_tasks – contains information about the last successful periodic tasks execution and its execution period in seconds.
The database provides the following VIEWS:
- view_events – the view contains the union of all EVENTS segment tables with statuses ONLINE, CURRENT, ONLINE AND BACKUPED and RESTORED.
- view_alarms – the view contains the union of all ALARMS segment tables with statuses ONLINE, CURRENT, ONLINE AND BACKUPED and RESTORED.