Redshift dialect: [...] after an expression is a subscript, not a quoted identifier #2960

RedshiftSqlDialect accepts [ as a delimited identifier quote. In Redshift, brackets after an expression index into a SUPER value, and identifiers are quoted only with double quotes.

select a[pg_backend_pid() - pg_backend_pid()] from (select json_parse('[1,2]') as a)

• sqlparser 0.64.0: Word { value: "pg_backend_pid() - pg_backend_pid()", quote_style: Some('[') }; parses as SELECT a AS [pg_backend_pid() - pg_backend_pid()] FROM ....
• Redshift: returns a = 1, i.e. a[0], so the bracket contents ran as an expression.

Docs: SUPER navigation (https://docs.aws.amazon.com/redshift/latest/dg/query-super.html) and identifier rules (https://docs.aws.amazon.com/redshift/latest/dg/r_names.html).