Comment by lfittl

Since there seems to be some confusion in the comments about why pg_query chose Protobufs in the first place, let me add some context as the original author of pg_query (but not involved with PgDog, though Lev has shared this work by email beforehand).

The initial motivation for developing pg_query was for pganalyze, where we use it to parse queries extracted from Postgres, to find the referenced tables, and these days also rewrite and format queries. That use case runs in the background, and as such is much less performance critical.

pg_query actually initially used a JSON format for the parse output (AST), but we changed that to Protobuf a few major releases ago, because Protobuf makes it easy to have typed bindings in the different languages we support (Ruby, Go, Rust, Python, etc). Alternatives (e.g. using FFI directly) make sense for Rust, but would require a lot of maintained glue code for other languages.

All that said, I'm supportive of Lev's effort here, and we'll add some additional functions (see [0]) in the libpg_query library to make using it directly (i.e. via FFI) easier. But I don't see Protobuf going away, because in non-performance critical cases, it is more ergonomic across the different bindings.

[0]: https://github.com/pganalyze/libpg_query/pull/321