I try to use Azure stream analytics to filter results that are too far from the last 2 reads. However, if last read is more than 720 minutes back (by reading time) I don't want to discard current read because of this difference.
I noticed the following is returning a read from 900 minutes back, which is unexpected as far as I can understand:
LAG(Reading,2)
OVER (PARTITION BY RegisterNumber LIMIT DURATION(minute, 720))
[BeforeLastReading]
I can ignore this read in my select query but I prefer to understand the reason before give up using the duration feature...