How to truncate a Postgresql's table from JDBC

Question

I have a Postgresql database and I want to truncate some tables using JDBC. How do I do that?

This is what I tried, but none worked... without even any error being reported:

Using CallableStatement.

try (Connection connection = getConnection();
     CallableStatement statement = connection.prepareCall("TRUNCATE " + tableName)) {
  return statement.execute();
}

Using Statement.

try (Connection connection = getConnection();
     Statement statement  = connection.createStatement()) {
  return statement.execute("TRUNCATE " + tableName);
}

Using PreparedStatement.

try (Connection connection = getConnection();
     PreparedStatement statement = connection.prepareStatement("TRUNCATE " + tableName)) {
  return statement.execute();
}

Answer 1

After the truncate, I need to commit:

try (Connection connection = getConnection();
     Statement statement = connection.createStatement()) {
  int result = statement.executeUpdate("TRUNCATE " + tableName);
  connection.commit();
  return result;
}

From the documentation:

TRUNCATE is transaction-safe with respect to the data in the tables: the truncation will be safely rolled back if the surrounding transaction does not commit.

Answer 2

You may run into issues if the table has dependencies. If so, truncate the parent tables first, and also use the CASCADE option.

Connection connection = getConnection();
try {
    PreparedStatement statement  = connection.prepareStatement("TRUNCATE " + parentTable1, parentTable2, ... + " CASCADE");
    try {
        return statement.execute();
    } finally {
        statement.close();
    }
} finally {
    connection.close();
}