Cloudwatch log insights sum() set default 0 value when no logs are present

Question

I'm trying to run the following Cloudwatch log insights query for two different log stream sources. However, when one or both streams have no entries, the sum() function returns a void result instead of 0. Because of that, I can't use that result in another stats operation. Do you know if it's possible to circumvent this behavior and make the sum() function return 0 when there are no results? Thanks!

stats
  sum(raw.stream_1.TotalBill) as stream_1_bill,
  sum(raw.stream_2.TotalBill) as stream_2_bill,
  stream_1_bill + stream_2_bill as total_bill

Expected result:

stream_1_bill: 0
stream_2_bill: 1
total_bill: 1

Received result:

stream_1_bill: 
stream_2_bill: 1
total_bill: 

Answer 1

I can achieve the desired result by using the coalesce function.

COALESCE(SUM(stream_1_bill),0)