Hi all,
I have a table "device_power" which has as its row key
"device_id.timestamp", and a single column, "power". A new row is
written whenever the power consumption of a device changes, which
could be every second, or could be as much as days.
When I do a query like "what was the average power of device X between
Date 1 and Date 2" I can get all keys where device_id matches X (using
PrefixFilter) and timestamp > Date1 and < Date2 (using either
RowFilter or setTimeRange). But I also need the last row before my
time range to know what state the device was in at the start of my
query period. Maybe an example will help make it more obvious (my
timestamps are long integers, but this is easier to read):
DevA.9am, 100W
DevB.10am, 200W
DevB.11am, 150W
DevA.12pm, 150W
And now the query "What was the average power of DevA btw 10am and
1pm". Is there a clever way to "get the first row before 10am that
matches PrefixFilter("DevA") ?
Thanks,
Oliver
