Hi，
是的，感觉你是对的。
`JdbcOutputFormat` 会被 wrap 在 `OutputFormatSinkFunction` 中，而
`OutputFormatSinkFunction` 没有继承 `CheckpointedFunction`，所以没法在 snapshotState
时候调用format.flush。
WDYT @Jark @ Leonard
Best,
Hailong
在 2020-12-09 17:13:14，"jie mei" <meijie.w...@gmail.com> 写道：
>Hi, Community
>
>JDBC connector似乎无法确保buffer中的数据在checkpoint的时候全部入库。这是因为
>OutputFormat中没有一个接口，供checkpoint的时候调用。 从JDBC的connector的
>代码来看，只能设定一个超时时间用以刷新数据，但还是可能存在丢数据的case。
>
>我的问题是：是否有办法强制刷新buffer中的数据入库？
>
>
>@Public
>public interface OutputFormat<IT> extends Serializable {
>
> /**
> * Configures this output format. Since output formats are
>instantiated generically and hence parameterless,
> * this method is the place where the output formats set their
>basic fields based on configuration values.
> * <p>
> * This method is always called first on a newly instantiated output format.
> *
> * @param parameters The configuration with all parameters.
> */
> void configure(Configuration parameters);
>
> /**
> * Opens a parallel instance of the output format to store the
>result of its parallel instance.
> * <p>
> * When this method is called, the output format it guaranteed to
>be configured.
> *
> * @param taskNumber The number of the parallel instance.
> * @param numTasks The number of parallel tasks.
> * @throws IOException Thrown, if the output could not be opened
>due to an I/O problem.
> */
> void open(int taskNumber, int numTasks) throws IOException;
>
>
> /**
> * Adds a record to the output.
> * <p>
> * When this method is called, the output format it guaranteed to be opened.
> *
> * @param record The records to add to the output.
> * @throws IOException Thrown, if the records could not be added to
>to an I/O problem.
> */
> void writeRecord(IT record) throws IOException;
>
> /**
> * Method that marks the end of the life-cycle of parallel output
>instance. Should be used to close
> * channels and streams and release resources.
> * After this method returns without an error, the output is
>assumed to be correct.
> * <p>
> * When this method is called, the output format it guaranteed to be opened.
> *
> * @throws IOException Thrown, if the input could not be closed properly.
> */
> void close() throws IOException;
>}
>
>
>--
>
>*Best Regards*
>*Jeremy Mei*
