rdbOracle-OracleHistoryDeviceExt
This component is the Oracle implementation of HistoryDeviceExt, and a child of a the OracleDatabase component.
The History Device Extension is fully described in the Niagara Drivers Guide.
You access these properties by expanding followed by right-clicking Histories and clicking
| Property | Value | Description |
|---|---|---|
| Retry Trigger | additional properties | Defines how frequently to
attempt a failed operation again. This continues until successful
execution occurs. Appears in the Nav tree but not in any manager view and is unique in that it requires no linking of its output for operation. Getting Started with Niagara documents Retry Trigger properties. |
| Use Last Timestamp | true or false (default) | Enables and disables
the reporting of the last date and time on a history record. false queries the database for the last timestamp in the database every time an export descriptor processes data. Depending on the size of the database table and the number of export descriptors being processed, this can be a time consuming activity. true stores the last timestamp as a property on the export descriptor each time it processes the export. This efficiency-related setting helps with overall system performance when exporting data. |
| Use History Config Time Zone | true or false (default) | Configures how to normalize
the timestamp before writing it to the external database. It includes
the time zone. false normalizes values to the Supervisor station’s time zone. true writes the original
timestamp value (retained by the Supervisor) to the external database.
Unfortunately, this option ignores the time zone. This causes difficulties
with local time zones, especially in relation to daylight savings
time. The Timestamp Storage property exports
or updates history timestamps to Coordinated Universal Time (UTC). Note: The effect of these History properties may be irrelevant depending
upon the setting of theTimestamp Storage |
| Always Create Index For New Tables | true or false (default) | Configures histories regarding
index creation for new tables. It specifies whether indexes should
always be created for new exported history tables. true ensures that an index on created RDBMS tables for exported histories is always created, no matter what the configuration of other properties is. false may not create a new index when exporting new tables. The driver may still create indexes based on the configuration of other properties (for example, if Use Last Timestamp is false, indexes get created no matter what). If this property is false and the Use Last Timestamp property is set to true, an export may not create indexes for the exported tables. Setting this property to true in that scenario would cause any new tables created going forward to also have a proper index created. You can subsequently use the Migrate To Optimized Table Indexes action against existing exported tables (also those prior to Niagara 4.11) to migrate them and ensure that updated indexes are created in the RDBMS. Creating indexes for exported tables can help maximize query performance. |
Actions
Retry downloads histories again.
Migrate To Optimized Table Indexes (introduced in Niagara 4.11) can be used against existing RDBMS installations (prior to Niagara 4.11) to migrate the existing RDBMS tables and ensure that updated indexes are created in the RDBMS. Coordinate with your DBA before you execute this action. The updated indexes maximize query performance, but this action is not mandatory. Since this optional action affects the tables in the existing RDBMS, this migration does not happen automatically but requires you to manually invoke the action. Invoking this action kicks off a job in the JobService where you can monitor the migration progress and results.
This action is not a requirement and therefore optional. Also check with your DBA before performing this action since it affects the tables in the existing RDBMS.