Exporting by History ID

Each exported history is stored within a dedicated table with a name corresponding to the history name in NiagaraAX. Duplicate names are suffixed with an incrementing number to ensure uniqueness and they can be traced back to their source via the descriptive HISTORY_CONFIG table.

NOTE: For an Oracle database, the maximum length of a table name is 30 characters.

In this example:

ID is maintained by the RdbmsNetwork and is used for database indexing but not used by the Niagara station.
TIMESTAMP records when the value was logged and can be localized to the exporting station or the source station. This choice is stored in the HISTORY_CONFIG table.
The VALUE column data type will change according to the type of the point exported. e.g. double, float, enum, string or boolean.
VALUE can be {null}. e.g. where {NaN} is recorded in the source history.
Point facets (e.g. units) are not exported to the database.

The data types of the HISTORY_CONFIG table are:

When exporting by ID the relationship between the RDBMS driver and the exported tables is inventoried in the HISTORY_CONFIG table as in this for example:

The data types of this example are:

The SOURCE column shows the origin of the history. The source point ORD and the route taken exported up to supervisor are separated by a space. It is occasionally necessary to extend the length of the SOURCE column when station naming conventions make the ORDs very long. This would be performed by the DBA using SQL or database management tools. This condition would exhibit itself as a “Data Truncation” error in the application director output of the station.

The INTERVAL column shows the collection interval of the source history extension in milliseconds, the string prefix is “false” for Interval type histories.