On 20 Mar 2019, at 18:38, Kirill Shcherbatov <kshcherbatov@tarantool.org> wrote:

Tarantool could not start from the snapshot created by version
2.1.0 because the new version 2.1.1 does not support the
index.opts.sql index opt and stops the execution.
Introduced a special state OPT_DEF_LEGACY macro to ignore legacy
options and introduced migration code in upgrade.lua.

As for me, it looks satisfying, but I strongly recommend you to ask
other members of server team for comments on this approach.
Will there be other “legacy” options, or in the nearest future this is
going to be the only one? Moreover, opts_parse_key already features
“skip_unknown_options” param - could we skip “sql” option using it
(ofc considering some workaround)?

Again, since it is not directly related to the main patch-set, let’s
consider it as independent. 

LGTM.

I've rebased this separate patch on the branch 
kshch/migration-fixup
you may cherry-pick it if it is really reasonable.