[Tarantool-patches] [PATCH] net.box: fix fetching of schema of an old version

[Alexander Turenko]

On Wed, Apr 01, 2020 at 11:45:21PM +0300, Alexander Turenko wrote:
> After 2.2.0-633-gaa0964ae1 ('net.box: fix schema fetching from 1.10/2.1
> servers') net.box expects that _vcollation system view exists on a
> tarantool server of 2.2.1+ version. This is however not always so: a
> server may be run on a new version of tarantool, but work on a schema of
> an old version.
> 
> The situation with non last schema is usual for replication cluster in
> process of upgrading: all instances run on the new version of tarantool
> first (no auto-upgrade is performed by tarantools in a cluster). Then
> box.schema.upgrade() should be called, but the instances should be
> operable even before the call.
> 
> Before the commit net.box was unable to connect a server if it is run on
> a schema without _vcollation system view (say, 2.1.3), but the server
> executable is of 2.2.1 version or newer.
> 
> Follows up #4307
> Fixes #4691
> ---
> 
> https://github.com/tarantool/tarantool/issues/4691
> https://github.com/tarantool/tarantool/tree/Totktonada/gh-4691-net-box-connect-schema-2-1-3

Forgot to add the changelog entry.

```
## Bugs fixed

### Lua

* net.box: fixed inability to connect 2.2.1+ server before
  box.schema.upgrade() is called on the server (gh-4691)
```