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References: <65798b71932c21183072decd2cce8b2b0f88b884.1585773275.git.alexander.turenko@tarantool.org>
From: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
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Date: Sat, 4 Apr 2020 00:53:53 +0200
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Subject: Re: [Tarantool-patches] [PATCH] net.box: fix fetching of schema of
 an old version
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To: Alexander Turenko <alexander.turenko@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org

Hi! Thanks for the patch!

On 01/04/2020 22:45, 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
> 
>  src/box/lua/net_box.lua                       |   9 ++
>  ...4691-net-box-connect-schema-2-1-3.test.lua |  93 ++++++++++++++++++
>  test/box-tap/no_auto_schema_upgrade.lua       |  30 ++++++
>  .../snap/2.1.3/00000000000000000000.snap      | Bin 0 -> 4466 bytes
>  4 files changed, 132 insertions(+)
>  create mode 100755 test/box-tap/gh-4691-net-box-connect-schema-2-1-3.test.lua

We have xlog/upgrade suite specifically for these tests. With
already designed processes, where and how to store old snaps, etc.
See xlog/upgrade/how_to_add_new_test.md.