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Mastering Internet of Things by Peter Waher

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Removing old data

We cannot continue storing new values without also having a plan for removing old ones. Doing so is easy. We choose to delete all records older than 100 minutes. This is done by first performing a search, and then deleting objects that are found in this search. The search is defined by using filters from the Waher.Persistence.Filters namespace:

foreach (LastMinute Rec2 in await Database.Find<LastMinute>( 
   new FilterFieldLesserThan("Timestamp",  
   Timestamp.AddMinutes(-100)))) 
{ 
   await Database.Delete(Rec2); 
} 

You can now execute the application, and monitor how the MinuteValues collection is being filled.

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