I have a sample code, which creates a table, inserts some rows in it and then tries to cancel the whole transaction, but conn.rollback() seems to have effect only on INSERT statements while CREATE TABLE keeps unaffected: a newly created table remains permanent in the database with no rows inserted in it.
Is this a standard behavior while using JDBC driver with MySQL DBMS?
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class TestBatch {
public static void main(String[] args) {
try (Connection conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/testdb?serverTimezone=UTC",
"root", "root")) {
// drop table
try (Statement dropStatement = conn.createStatement()) {
dropStatement.executeUpdate("DROP TABLE IF EXISTS mytable");
}
// create table, insert rows and rollback
conn.setAutoCommit(false);
try (Statement stmt = conn.createStatement()) {
stmt.addBatch("CREATE TABLE mytable (id INT)");
stmt.addBatch("INSERT INTO mytable VALUES (1)");
stmt.addBatch("INSERT INTO mytable VALUES (2)");
stmt.executeBatch();
conn.rollback();
} finally {
conn.setAutoCommit(true);
}
} catch (SQLException e) {
System.err.println(e.getMessage());
}
}
}
Please, note, I'm using MySQL Server 8.0 with Connector/J ver. 8.0.17, also the parameter default-storage-engine (in C:\ProgramData\MySQL\MySQL Server 8.0\my.ini) is set to INNODB.
As Paul Spiegel and Arnaud said, DDL statements cannot be rolled back in MySQL. This is true even for MySQL 8: https://dev.mysql.com/doc/refman/8.0/en/implicit-commit.html
For better or worse, DDL statements commit any pending transactions, if they are local and cannot be used in XA transactions (because that would cause one participant to commit data without the transaction coordinator issuing the command to do so).