Recent History (preserving history): Difference between revisions

Recent History (preserving history) (view source)

Revision as of 15:51, 16 June 2022

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 {{Template:Version badge Mx}}{{Version badge 1}}This Wiki page applies to all Cumulus flavours (including the abandoned Cumulus 2).
-[[Category:Terminology]]
+[[Category:Terminology]] [[Category:Cumulus Files]]
 =What is Recent History?=
-Recent history functionality in Cumulus is the ability to store weather values, at up to 1 minute intervals, for the last 7 days.
+Recent history functionality in Cumulus is the ability to store weather values, for the last 7 days.
-It is important to realise, these are spot readings, and will miss any extremes that occur between the times when the recent history values are stored. The weather value that tends to vary the most is wind speed, so that is where peaks are most often missed.
+Only some spot readings are stored in Recent History, the stored values will miss any extremes that occur between the times when the recent history values are stored. The weather value that tends to vary the most is wind speed, so that is where peaks are most often missed.
-It is also important to realise that weather stations are not supplying values to Cumulus on a continuous basis, depending on the weather station type values may be available at various intervals, either every so many seconds or perhaps at a rate less than once a minute. This can mean that the readings stored on a 1-minute basis may actually be duplicates if the station has not supplied a new value since the previous minute.
+When Cumulus is running normally, entries are stored once a minute, regardless of how often Cumulus interrogates the weather station (might be every 10 seconds, or more or less frequently) and regardless of how often the weather station gets updated readings from sensors (might be every few seconds, every 40 seconds, every minute or less frequently). This can mean that the readings stored on a 1-minute basis may actually be duplicates if the station has not supplied a new value since the previous minute, or may not capture every reading from sensors if they are read more than once in a minute.
+When Cumulus is restarted, if the weather station provides historical catch-up data, then the interval between entries for that period when Cumulus was not running, is stored at whatever interval the historical catch-up data uses.  Since release 3.12.0, entries less than a week old, from when MX was previously running will be retained, and those will be at one minute interval; earlier releases will not collect any entries from when Cumulus was previously running, just those for up to a week while it was not running.
 =How is the functionality used?=