Time Series Database Cache Module by Automation Professionals
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Query a registered time series cache for data within a timestamp range, immediately returning any cached data. Missing data is retrieved from the data source in the background. Call repeatedly to obtain additional data as it arrives.


system.db.getSeriesCache(handle, begints, endts, [gapTolerance,] valuecolumns[]) returns Dataset

ArgumentData TypeDescription
handleLongNumeric handle from registerSeriesCache().
begintsDateQuery start timestamp. Must not be null.
endtsDateQuery end timestamp. Must not be null.
gapToleranceLongOptional, Milliseconds. Insert a null row when consecutive timestamps are further apart than this tolerance.
valuecolumnsString[]List of Strings defining the value columns to be delivered.

Usage Notes

If there is a chance you won't call the getSeriesCache() function often enough to keep the handle from expiring, you should wrap a first attempt in a try/except block, where the except clause obtains a fresh handle.

The Dataset returned is actually a supporting subclass: SeriesFragment. It carries additional properties and methods that can describe the progress of the cache query.

See the timeSeriesCache expression function for a description of the underlying cache behavior.