Support SELECT ALL

[aquarapid]

Vitess does not support the SELECT ALL construct. This is the counterpart to SELECT DISTINCT, and is the default. As such, you can just drop the ALL from the query, and everything will work as expected.

However, in the spirit of compatibility, we should support the keyword in this context.

Example against recent master:

mysql> create table t1(c1 int, primary key(c1));                                                                      
Query OK, 0 rows affected (0.10 sec)

mysql> SELECT ALL * from t1;
ERROR 1105 (HY000): vtgate: http://localhost:15001/: syntax error at position 11 near 'ALL'

Running the same against the underlying MySQL (8.0.21):

mysql> SELECT ALL * from t1;                    
Empty set (0.00 sec)