f0:string f1:int f2:int f3:double (all can be null)
primary key: f0,f1,f2
partition key: f1
bucket key: f2
bucket count: 2
add deletion vector

Msgs:
snapshot-1-2 (3 data files)
Add: Two roads diverged in a wood, and I took the one less traveled by, And that has made all the difference., 10, 1, 11.0
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: Alex, 10, 0, 16.1
Add: David, 10, 0, 17.1

Add: Lucy, 20, 1, 14.1
Add: Paul, 20, 1, 18.1
Compact


snapshot-3-4 (4 data files)
Add: Whether I shall turn out to be the hero of my own life., 10, 1, 19.1
Add: Lily, 10, 1, 20.1

snapshot-5-6 (5 data files and 2 deletion file: in bucket-1 deletion file has one bitmap for Tony; in bucket-0 deletion file has two bitmap for Alice and Lily, as they are in different files)
Delete: Tony, 10, 0, 14.1
Add: Alice, 10, 1, 19.1
Delete: Lily, 10, 1, 20.1
Compact

snapshot-7-8 (3 data files and 1 deletion file, as data in bucket-0 are merged into one file)
Update after: Alice, 10, 1, 21.1
Compact


data_split-01
with snapshot-2, partition-10, bucket-0

data_split-02
with snapshot-6, partition-10, bucket-1

data_split-03
with snapshot-6, partition-10, bucket-0

data_split-04
with snapshot-8, partition-10, bucket-0

