Add postgreSql column default interval

[griffio]

close #4122

• Add PostgreSql specific grammar
• Update fixture test

This brings the PostgreSql grammar to similar level of MySql support for Interval

Provides grammar for:

  some_interval_a INTERVAL DEFAULT INTERVAL '5 days',
  some_interval_b TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP - INTERVAL '5 days',
  some_interval_c TIMESTAMP NOT NULL DEFAULT NOW() - INTERVAL '5 days',
  some_interval_d INTERVAL DEFAULT INTERVAL '3h' + INTERVAL '20m'

Note:- Does not support
arithmetic e.g INTERVAL ’1 day’ * 7
“::interval” short-hand
“5 days” validation of literals
Modifiers e.g INTERVAL ‘5’ DAY

Other examples of Interval expressions that could be supported
https://github.com/postgres/postgres/blob/master/src/test/regress/sql/interval.sql

[hfhbd]

Could you also add an integration test:
SELECT INTERVAL '20m'

Maybe we also need support in the type resolver or bnf to return a PostgreSqlType.INTERVAL.

[griffio]

I was looking into that. 👓

My understanding of expression INTERVAL '20m' is not a function call with parentheses like NOW(), the function_expr won't match it and PostgreSqlTypeResolver won't be used.

It's more like a dynamic column type with an argument.

Use 1: SELECT NOW() - INTERVAL '1 year 3 hours 20 minutes'
Use 2: SELECT * FROM T1 WHERE T1.subscription = INTERVAL '@ 1 month';'

Also - it could be argued that INTERVAL is a new token could be added to sql-psi SqlLexer.flex.
(If that project is still used)

We could merge what is currently working and then a new PR to work out the extended INTERVAL syntax (Sqlite doesn't support INTERVAL).

[hfhbd]

Yeah, I am fine with the current state.
Of course we still use sql-psi, its the frontend of the compiler.

My understanding of expression INTERVAL '20m' is not a function call with parentheses like NOW(), the function_expr won't match it and PostgreSqlTypeResolver won't be used.

Yes, this is true. We would need to overwrite the literal expressions. But I could also do it myself :)