After upgrading MySQL Connector/J from 9.4.0 to 9.5.0, connections to OceanBase (MySQL mode) work, but PreparedStatement queries return zero rows. The same SQL works with a plain Statement, and the same JDBC setup against MySQL 8 still works.

Environment

• OceanBase CE 4.3.5.x (MySQL compatibility mode), Docker

• SELECT VERSION(); → 5.7.25-OceanBase_CE 4.3.5.x

• Connector: mysql-connector-j 9.5.0

• JDBC URL includes useServerPrepStmts=true

Table

CREATE TABLE jdbc_test (
  id INT UNSIGNED NOT NULL AUTO_INCREMENT,
  name VARCHAR(50) NOT NULL,
  PRIMARY KEY (id)
);
INSERT INTO jdbc_test (id, name) VALUES (1, 'Jack');

Java

try (Connection conn = ds.getConnection();
     Statement stmt = conn.createStatement();
     ResultSet rs = stmt.executeQuery("SELECT name FROM jdbc_test WHERE id = 1")) {
    while (rs.next()) {
        System.out.println(rs.getString("name")); // prints Jack
    }
}

try (Connection conn = ds.getConnection();
     PreparedStatement ps = conn.prepareStatement("SELECT name FROM jdbc_test WHERE id = 1");
     ResultSet rs = ps.executeQuery()) {
    while (rs.next()) {  // never enters loop
        System.out.println(rs.getString("name"));
    }
}

What I tried

• Rolled back to 9.4.0 → PreparedStatement works again

• With 9.5.0, setting useServerPrepStmts=false → also works

• SELECT VERSION() always returns a row on 9.5.0; only table SELECT queries via PreparedStatement seem affected.

Question: Is this a known interaction between Connector/J 9.5 server-side prepared statements and OceanBase’s MySQL protocol layer, or should I treat it as a driver config issue on my side?