googlesql

I mean the postgres parser (and semantic changes) for ZetaSQL. The zetasql parser is in a file called zetasql/parser/bison_parser.y, I strongly suspect they now have a file called something like zetasql/pgparser/bison_parser.y as well (and much more pervasive changes to support the deeper differences in the dialects). This is the lexical structure and syntax docs for the new postgres inteface to cloud spanner: https://cloud.google.com/spanner/docs/postgresql/lexical And this is the zetasql lexical structure and syntax docs: https://github.com/google/zetasql/blob/master/docs/lexical.m... Notice that the new PG docs are an edit of the Zeta ones - evidence that my hypothesis is correct.

The Cloud Spanner SQL frontend/analyzer has been open sourced by google as ZetaSQL. https://github.com/google/zetasql It is amazingly good. You give it textual SQL (+ schema + all your function definitions) and it returns a really clean logical query plan. It is also happy to do this via a protobufs so you can use it from languages other than C++. It is also tested and documented up the wazoo. It has been such a pleasure to work with. Anyway, the big problem with ZetaSQL is that it is not a common SQL dialect. It seems that the only reasonable way to do this PostgreSQL interface for Cloud Spanner is to add a second parser (and other extensions) to ZetaSQL. If I am correct, I really really hope they open source that part of ZetaSQL as well - it would be a massive step forward for open source SQL tooling.

ZetaSQL[1] seems like it could be a fit for your use case. I've worked with Apache Calcite in the past and found it to be very complex to work with. I found ZetaSQL to be a little easier to use. [1] https://github.com/google/zetasql