Time Series Database Cache Module by Automation Professionals
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system.db.getSeriesCache

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.

Syntax

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.