Explore adding graph query capabilities to PartiQL

[jpschorr]

SQL/PGQ (Property Graph Query) is coming as part 16 of SQL 2023 and will share a graph pattern matching language with GQL (Graph Query Language) which is also moving through ISO standardization.

PartiQL should consider adding graph query capabilities with a query grammar and operational semantics conformant with GPML (to the extent possible).

See

• GPML as outlined by Graph Pattern Matching in GQL and SQL/PGQ.
• https://news.ycombinator.com/item?id=30300852
• https://www.w3.org/Data/events/data-ws-2019/assets/slides/KeithWHare-2.pdf