When exporting from HDFS to DB, If an export map task fails due to these or
other reasons, it will cause the export job to fail. The results of a
failed export are undefined. Each export map task operates in a separate
transaction. Furthermore, individual map tasks commit their current
transaction periodically. If a task fails, the current transaction will be
rolled back. Any previously-committed transactions will remain durable in
the database, leading to a partially-complete export.
When using DBOutputFormat in custom map\reduce program:
When emitting from multiple mappers or reducers and if any one of the
mapper or reducer got failure only the failed transaction will be rolled
back Any previously-committed transactions will remain durable in the
database, leading to a partially-complete export.
Is there any way to commit at last to avoid partially-complete?
Alberto Andreotti 2012-08-23, 15:40