[SQOOP-969] sqoop export with mysql connector uses more than twice as many mappers as the --num-mappers hint

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.4.3
• Component/s: connectors
• Labels: newbie
• Assignee: Unassigned
• Reporter: Will McQueen
• Created: 26/Mar/13 23:56
• Updated: 15/Sep/15 23:59

Description

sudo -u sqoop sqoop export --connect "jdbc:mysql://<hostname>/sqoop" --username sqoop --password sqoop --table quicktest --verbose --export-dir /user/sqoop/quicktest --num-mappers 12

...results in more than twice the number of mappers (according to the logs) as the specified '12' hint:

13/03/26 16:20:35 INFO mapred.JobClient: Job Counters
13/03/26 16:20:35 INFO mapred.JobClient: Launched map tasks=23

...and I couldn't help notice that the logs also say:
13/03/26 16:19:03 DEBUG mapreduce.ExportInputFormat: Target numMapTasks=12
13/03/26 16:19:03 DEBUG mapreduce.ExportInputFormat: Total input bytes=23

...where # input bytes maches # launched map tasks. Coincidence, or relation?