I have a compound mongo index where one of a field is SerialNumber
it runs faster when it have value like
SerialV1_72:68:6b:ac:5e:30
SerialV1_85:75:a9:b1:d9:d7
it runs slow when it have value like
serial_bdee115bb9f2
serial_aa1c2385e9f1
Please suggest.