the JDBC Sink completely ignores the taskNumber and parallelism.


On 12.09.2016 08:41, Swapnil Chougule wrote:
Hi Team,

I want to know how tasknumber & numtasks help in opening db connection in Flink JDBC JDBCOutputFormat Open. I checked with docs where it says:
taskNumber - The number of the parallel instance.
numTasks - The number of parallel tasks.
But couldn't get clear idea among parallel instance & parallel tasks. How do they contribute in concurrency with JDBC Source/Sink?

I also checked with code but couldn't drill down further

* Connects to the target database and initializes the prepared statement.
* @param taskNumber The number of the parallel instance.
* @throws IOException Thrown, if the output could not be opened due to an
* I/O problem.
public void open(int taskNumber, int numTasks) throws IOException {
try {
upload = dbConn.prepareStatement(query);
} catch (SQLException sqe) {
throw new IllegalArgumentException("open() failed.", sqe);
} catch (ClassNotFoundException cnfe) {
throw new IllegalArgumentException("JDBC driver class not found.", cnfe);

private void establishConnection() throws SQLException, ClassNotFoundException {
if (username == null) {
dbConn = DriverManager.getConnection(dbURL);
} else {
dbConn = DriverManager.getConnection(dbURL, username, password);