id:int attrs:map(string, int) (all can be null)
no partition key
no primary key
bucket count: -1
file format: orc

Rows (snapshot-1):
Add: [1, {"one": 10}]
Add: [2, {"two": 20}]
Add: [3, {null: 30}]
NoCompact

The third row contains a null MAP key and is expected to fail during reading.
