[tarantool-patches] Re: [PATCH 24/25] Introduce _vinyl_deferred_delete system space

[Vladimir Davydov]

On Wed, Aug 01, 2018 at 11:25:01PM +0300, Konstantin Osipov wrote:
> * Vladimir Davydov <vdavydov.dev at gmail.com> [18/08/01 18:14]:
> > On Tue, Jul 31, 2018 at 11:54:27PM +0300, Konstantin Osipov wrote:
> > > * Vladimir Davydov <vdavydov.dev at gmail.com> [18/07/27 16:55]:
> > > > The space is a blackhole. It will be used for writing deferred DELETE
> > > > statements generated by vinyl compaction tasks to WAL so that we can
> > > > recover deferred DELETEs that hadn't been dumped to disk before the
> > > > server was restarted.
> > > 
> > > Why do you actually need a proto space for it? Please feel free to
> > > put blackhole engine first in the list of engines.
> > 
> > You mean making this space purely virtual? No record in _space, no info
> > in snap file, just struct space in the cache?
> 
> No, I mean no changes in sc_* methods, only a record in _space?

But we need to install on_replace trigger on that space. OTOH we can do
that in vinyl_engine_bootstrap or vinyl_engine_begin_initial_recovery -
obviously the space isn't used during recovery from memtx snapshot, we
only need the trigger on final recovery. Looks reasonable. Is this what
you mean?