CheckNotExists is checked in the prewrite phase and should not appear in the commit phase.

[gfreezy]

fixed #315

When we set the primary key of a transaction, the corresponding operation must not be CheckNotExists.

@ekexium CheckNotExists is already checked when set primary key.

[ekexium]

The change itself looks good to me.

I'd prefer to fix the primary key issue and add a test in the same PR to close #315 .

[andylokandy]

Can we merge it now?

[ekexium]

I think a test case is needed.