`interval '1 month - 1 day'` is a valid PG interval but invalid in RW

[stdrc]

dev=> select interval '1 month - 1 day';
ERROR:  Failed to run the query

Caused by these errors (recent errors listed first):
  1: Failed to bind expression: INTERVAL '1 month - 1 day'
  2: Bind error: Invalid interval: -

[hasyimibhar]

Is the end goal to uncomment all the test cases here? https://github.com/risingwavelabs/risingwave/blob/main/src/tests/regress/data/sql/interval.sql
Including making IntervalStyle behave just like Postgres?

[stdrc]

Is the end goal to uncomment all the test cases here? main/src/tests/regress/data/sql/interval.sql
Including making IntervalStyle behave just like Postgres?

The direct goal is simply allow space after the negative sign. If you're willing to contribute, you can try uncomment those test cases and support all, but I guess it won't be too easy to do it all.

[chagelo]

Is there a way to get the global variable of SessionImpl? Risingwave seems to store the Interval style(sql_standard, postgres, etc.) int SessionImpl always(set intervalstyle to 'postgres';), in parser I need to distinguish the interval style, there are some crucial differences between those different style.

Usually the default interval style is postgres in postgres.

[xiangjinwu]

We did not intend to support all of the interval styles, which introduces complexity with low usage. Just assume it is always the default postgres.