Dolt drops sql_select_limit

[Yibo-Dong]

What happened

Dolt returns all four rows for a legal SELECT DISTINCT whose projection is a ROW_NUMBER() window, even though the session sql_select_limit is 2. Unsure whether this is ignored or just unsupported?

Environment

Dolt main (commit c3b5ce3c67f8677ca08a0a58d8c03cdc95bff8b7). MySQL version 8.0.43.

How to reproduce

Run the corresponding SQL in a fresh Dolt repository.

CREATE TABLE t(id INT PRIMARY KEY, g INT NOT NULL);
INSERT INTO t VALUES (1, 0), (2, 0), (3, 1), (4, 1);

SET @@sql_select_limit = 2;
SELECT DISTINCT ROW_NUMBER() OVER (ORDER BY id) AS rn
FROM t
ORDER BY rn;

Expected Result

MySQL defines sql_select_limit as the maximum number of rows returned by a SELECT; an explicit LIMIT takes precedence. Window evaluation occurs before ORDER BY, LIMIT, and SELECT DISTINCT, so the four row numbers are formed, the result is distinct, and the first two ordered rows are returned. See the
MySQL sql_select_limit documentation and MySQL window execution order.

The independent SQLite 3 oracle, run with an equivalent explicit LIMIT 2, returns:

rn
1
2

[angelamayxie]

It seems like respecting @@sql_select_limit doesn't seem to have been implemented at all.