Instructions
The tag history splitter module adds a new type of tag history provider that simply points to two other providers. Data stored to the new provider is "split" to both, storing the same data in each.
Configuration
After installation, you will find that you can now create additional tag history providers under Configure>SQLTags>Historian in the gateway. To use the splitter, simply do the following:
Create two database connections (if they don't already exist), one for the primary data, and one for the secondary.
Go to Historian, and select "Create new Historical Tag Provider".
Select the splitter, and continue.
Select the two connections, and save.
In your tag configuration, start using your splitter connection as the target data store.
Querying
When you query against a splitter connection, the system selects one of the underlying providers to query. By default, the "first connection" will always be used. By specifying a max time range in the splitter settings, though, you can cause the system to query the second connection when the query range is beyond the specified amount of time. In this way you can create systems that, for example, store data locally with a prune size of two weeks, and remotely with no data pruning. When you set the query limit for 2 weeks, queries inside that will execute locally, and otherwise will execute against the remote server.