[tarantool-patches] Re: [PATCH 1/3] vinyl: fix secondary index divergence on update

[Vladimir Davydov]

On Sat, May 25, 2019 at 11:28:51PM +0300, Konstantin Osipov wrote:
> * Vladimir Davydov <vdavydov.dev at gmail.com> [19/05/25 22:55]:
> > On Sat, May 25, 2019 at 09:11:57AM +0300, Konstantin Osipov wrote:
> > > Could you also please explain why you decided to introduce a new
> > > flag, and not use is_overwritten?
> > 
> > is_overwritten is cleared on rollback while is_nop stays unchanged.
> 
> Then shouldn't better name be is_overwriting, as every
> is_overwritten txv is overwritten by some is_overwriting txv
> (is_nop)? Is there any symmetry between the two or there are cases
> when they are unrelated?

No.

is_nop is set if a statement has no effect and can be skipped on commit,
e.g. DELETE following REPLACE in case of a secondary index.

Not every statement that overwrites some other statement has no effect,
e.g. REPLACE following other REPLACE can't be skipped.