f0:string f1:int f2:int f3:double (all can be null)
partition key: f1, f2
bucket count: default

Msgs:
snapshot-1
Add: Alice, 10, 1, 11.1
Add: Bob, 10, 0, 12.1
Add: Emily, 10, 0, 13.1
Add: Tony, 10, 0, 14.1
Add: Lucy, 20, 1, 14.1
NoCompact

snapshot-2
Add: Emily, 10, 0, 15.1
Add: Bob, 10, 0, 12.1
Add: Alex, 10, 0, 16.1
Add: Paul, 20, 1, null
NoCompact

snapshot-3
Add: David, 10, 0, 17.1
NoCompact
