How does the tag historian pens work?
Is each pen a query or does it box up into a single query?
I am working on trying to make our historian db more efficient.
Wondering if there is a more efficient way to do charts for historian db pens
Hi Brent_Osterkamp1,
Tag Historian pens represent individual tags. However, the chart is taking all of those tags and is placing them all in a single query directly against the tag history tables. So, for example, if I set my chart to display 1 month of data with several different pens, there will be a single query ran to pull 1 month of data from all of the tags on my chart.
You can do things such as manipulate the Aggregation Mode or Sample Size for the tag history pens you choose to display on your chart. Sample Size dictates how many data points will be returned per query while Aggregation mode refers to how the data is calculated. Both might be helpful in improving efficiency with your charts.
More on both Aggregation and Sample Size here:
I hope this helps!
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