multi-database transaction repro.sql

create database if not exists t;
create database if not exists t2;

use t;
create table if not exists x (id int);

delimiter //

create or replace procedure foo (i int) as
begin
    start transaction;
    insert into t.x values (i);
    insert into x values (i);
    commit;
end //

delimiter ;

use t2;
create table if not exists x (id int);

-- this will fail
use t2;
call t.foo (1);

-- this will succeed
use t;
call t.foo (1);