Hi guys, I'm integrating the comments of Chesnay to my PR but there's a couple of thing that I'd like to discuss with the core developers.
1. about the JDBC type mapping (addValue() method at [1]: At the moment if I find a null value for a Double, the getDouble of jdbc return 0.0. Is it really the correct behaviour? Wouldn't be better to use a POJO or the Row of datatable that can handle void? Moreover, the mapping between SQL type and Java types varies much from the single JDBC implementation. Wouldn't be better to rely on the Java type coming from using resultSet.getObject() to get such a mapping rather than using the ResultSetMetadata types? 2. I'd like to handle connections very efficiently because we have a use case with billions of records and thus millions of splits and establish a new connection each time could be expensive. Would it be a problem to add apache pool dependency to the jdbc batch connector in order to reuase the created connections? [1] https://github.com/fpompermaier/flink/blob/FLINK-3750/flink-batch-connectors/flink-jdbc/src/main/java/org/apache/flink/api/java/io/jdbc/JDBCInputFormat.java
