Cannot insert NULL value into a AUTO_INCREMENT column in a CONNECTed MariaDB table

I have a CONNECT to a MariaDB server table which contains an AUTO_INCREMENT column.

Trying to insert a NULL value into this column always fails, while acording to the specifications I would expect it to use the next auto_incremented value.

Minimal example using a locally installed MariaDB 10.9.3 server: (Problem came up originally when CONNECTing from a MariaDB 10.6.10 server to a MySQL 5.7 server – same effect.)¶

use test;

create table t0 (

  id int primary key AUTO_INCREMENT,

  name varchar(255)

) ENGINE=InnoDB;

create table t0_conn engine=CONNECT table_type=MYSQL

  connection='mysql://username:xyzzy@localhost/test/t0'; 

insert into t0 values ( null, 'test1' ); -- works OK

select * from t0_conn; -- works OK: 1 test1

insert int0 t0_conn values ( 2, 'test2' ); -- works OK

insert into t0_conn values ( null, 'test3'); -- ERROR 1048 (23000): Column 'id' cannot be null

Since directly inserting into the underlying table (t0) works OK, it seems that the CONNECT engine is over-eager in checking the NOT NULL condition that is implied by the primary key. Unfortunately, this makes the AUTO_INCREMENT feature unusable in the CONNECT engine.