Re: [Tarantool-patches] [PATCH v4 2/2] box: introduce _vsession_settings sysview

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

* Mergen Imeev <imeevma@tarantool.org> [19/11/27 14:22]:
> > Where do you get the value from to build the tuple?
> > 
> I get it from current_session()->sql_flags and
> current_session()->sql_default_engine.

OK, so my point is that they were put there as a historical
artefact of sqlite conversion. It seemed then as the most logical
place to put them. PRAGMAs were internal, so it was not a big
deal.

But going forward it's a dangerous place to store them, they should be
global - it fattens the session object, and if there are more
settings like these, there will be semantics issues. 

Besides, there will be a need for global counterpart anyway - since the
next logical question is how to reset the session defaults? 

I.e. I want all new sessions to get created with
sql_default_engine = vinyl, how do I do it?

Does my point make sense now?

> I think that the system view state is the same for all
> sessions. It is empty, it has the same methods. However, it
> can give different results, because when it gives tuples,
> it reads from the session state (current_session()) to
> create them.

This is a neat implementation, I agree.

-- 
Konstantin Osipov, Moscow, Russia