MySQL Alter table prevents rollback of DML (?) - mysql

Question

I have a Spring / JDBC application that relies heavily on MySQL rollback for unit tests. I'm finding that if I perform certain DDL operations - even on temporary tables - in those transactions, the rollback fails even on normal DML statements. For example:
#Test
#Rollback(true)
public void testRollbackProblem() {
template.update("create temporary table foo (id INTEGER )");
template.update("update forms set form_name = 'blah' where form_id = 1412");
template.update("alter table foo add (name text)");
}
After this test completes, that middle statement will be persisted and not rolled back. Is there a way to prevent that? Perhaps certain parameters passed to the alter statement?

Answer 1

This is MySQL limitations as far I know. CREATE TABLE and ALTER TABLE statements cause an implicit commit and can not be rolled back:
The CREATE TABLE statement in InnoDB is processed as a single transaction. This means that a ROLLBACK from the user does not undo CREATE TABLE statements the user made during that transaction.
See also MySQL documentation: https://dev.mysql.com/doc/refman/5.7/en/implicit-commit.html
Updated:
Because you're using CREATE TEMPORARY TABLE it actually shouldn't do implicit commit but it happens because when you're executing ALTER TABLE:
CREATE TABLE and DROP TABLE statements do not commit a transaction if the TEMPORARY keyword is used. (This does not apply to other operations on temporary tables such as ALTER TABLE and CREATE INDEX, which do cause a commit.) However, although no implicit commit occurs, neither can the statement be rolled back, which means that the use of such statements causes transactional atomicity to be violated. For example, if you use CREATE TEMPORARY TABLE and then roll back the transaction, the table remains in existence.