===test insert===
0
2
===test merge===
0
2
===test alter===
0
2
===test mutation===
0
['q','q','q']
===test skip_idx===
0
2
===test alter attach===
1	1	
2	1	
3	1	
4	2	Hello
5	2	World
1	1
2	1
3	1
4	2
5	2
6	3
7	3
===test alter update===
foo
foo
===test no pk===
0
2
0
2
===test a lot of marks===
0
4
0
7