[postgresql] grammar update

[petrov-aleksey]

Hi,

NULLS [NOT] DISTINCT parameter of CREATE UNIQUE INDEX, available since postgresql v15 (released October 2022), is not supported.

https://www.postgresql.org/docs/current/sql-createindex.html
https://github.com/postgres/postgres/blob/master/src/backend/parser/gram.y#L4114 (opt_unique_null_treatment)

Parser fails on regress example CREATE UNIQUE INDEX unique_idx1 ON unique_tbl (i) NULLS DISTINCT;
https://github.com/postgres/postgres/blob/master/src/test/regress/sql/create_index.sql#L390

Do you have plans to update postgresql grammar?

Thank you.