This seems to be a wire-protocol proxy for mysql -> SQL.
The default proxied database is dolt. I'm guessing this is extracted from dolt itself as that claims to be wire-compatible with mysql. Which all makes total sense.
Not a proxy in the traditional sense, no. go-mysql-server is a set of libraries that implement a SQL query engine and server in the abstract. When provided with a compatible database implementation using the provided interfaces, it becomes a MySQL compatible database server. Dolt [1] is the most complete implementation, but the in-memory database implementation the package ships with is suitable for testing.
We didn't extract go-mysql-server from Dolt. We found it sitting around as abandonware, adopted it, and used it to build Dolt's SQL engine on top of the existing storage engine and command line [2]. We decided to keep it a separate package, and implementation agnostic, in the hopes of getting contributions from other people building their own database implementations on top of it.
Really excellent work! For the curious, would you all be creating an in-memory database implementation that is postgres compatible for the doltgres project?
We are moving in that direction but it's not a primary goal at this point. Once we have more basic functionality working correctly in doltgres we will examine splitting off a separate package for it. The in memory implementation has a bunch of MySQL specific stuff in it right now and we're still learning what pieces need to be generalized to share code.
We didn't extract go-mysql-server from Dolt. We found it sitting around as abandonware, adopted it, and used it to build Dolt's SQL engine on top of the existing storage engine and command line [2]. We decided to keep it a separate package, and implementation agnostic, in the hopes of getting contributions from other people building their own database implementations on top of it.
[1] https://github.com/dolthub/dolt [2] https://www.dolthub.com/blog/2020-05-04-adopting-go-mysql-se...