Compatibility with MySQL Workbench

[dpordomingo]

discovered at https://github.com/src-d/empathy-sessions/issues/37

considering the old #361 (comment), I'm not sure if you already discarded the interoperability with MySQL Workbench, so feel free to direct close if it makes no sense at all 🗡️

I tried to connect to gitbase using MySQL Workbench 6.3 (even it's not explicitly supported by gitbase) and I found some issues that made Workbench to crash:

• current_user() is not supported
• show status is not supported
• show engines is not supported

I could mock data for all of them in local gitbase, and doing so Workbench was able to start with a warning:

Incompatible/nonstandard server version or connection protocol detected ().

A connection to this database can be established but some MySQL Workbench features may not work
properly since the database is not fully compatible with the supported versions of MySQL.

MySQL Workbench is developed and tested for MySQL Server versions 5.1, 5.5, 5.6 and 5.7

> Continue anyway           > Abort 

If you continue 😉 , Workbench opens the pannel with the connection, but there is no tables shown in the left panel, plus a log:

# 15:32:31  Error loading schema content
#           Error Code: 0
#           MySQL_ResultSet::getString: invalid value of 'columnIndex'

And fetching commits also fails:

select * from commits
# 15:35:27  select * from commits LIMIT 0, 10
#           Fetching...
# 15:35:27  select * from commits LIMIT 0, 10
#           Error Code: 0
#           0) . Please reportn charsetnr (

I wonder if you could give some hint to let someone work on this during some OSD 🤔 ... or just discourage it if you see it an impossible thing.