Re: [Tarantool-patches] [PATCH v2 0/5] replication: fix local space tracking

[Konstantin Osipov <kostja.osipov@gmail.com>]

* Serge Petrenko <sergepetrenko@tarantool.org> [20/03/18 22:52]:
> https://github.com/tarantool/tarantool/issues/4114
> https://github.com/tarantool/tarantool/tree/sp/gh-4114-local-space-replication
> 
> The patchset contains 2 of Georgy's patches perorming WAL gc rework.
> The first patch introduces a matrix clock structure, which contains the latest
> known vclocks of all the cluster members and can be used to build a vclock,
> which is less than or equal to all the member vclocks.
> Such a vclock is used then in the second patch, where gc is rewritten to stop
> tracking needed WAL files by vclock signature. Now replica vclocks are used to
> define which files are still needed.

One more follow up. While I don't like the approach with matrix
clock, I accept there may be an issue with the current way GC
subsystem tracks replicas.

Could you add issue description to the changeset comment? What's
the problem with using clock signature to keep track of relays?
And if there is an issue with gc signature, let's switch to
vclocks instead, but why build a matrix? 


-- 
Konstantin Osipov, Moscow, Russia