Question one:
Encounter this problem during the upload process:
ERROR tool.ExportTool: Encountered IOException running export job: java.io.IOException: No columns to generate for ClassWriter
Solution:
When searching online version of the driver is too low due to a lot of blog said that when, in fact, try this method when we can start with this: add a command line, - drsiver com.mysql.jdbc.Driver \ then the problem is solved! ! !
Question two:
Export is still time, will complain, but we are very amazing discovery, as well as some data is imported. This is the next question.
Caused by: java.lang.NumberFormatException: For input string: "null"
Solution: Because the data resulting from the presence of null worth
Add a line in the command (in a manner of modifications, Second way is to change my format): - input-null-string '\\ N' \ and some bloggers say that the increase in two rows, but I can also add a line specific reasons no scrutiny.
Q Leg three:
java.lang.RuntimeException: Can't parse input data: '1998/5/11'
Problems like this occur, mostly because the data with relational database on HDFS create a table of field type mismatch caused. After careful comparison modified, this would not have given it! !
Of course, the problem will certainly not happen to such a point, mainly rely on the usual accumulation, modification, in order to continue to grow.
Note: Do not make like a knock on the wrong letter, command or wrong, less space to play such a stupid mistake, this will be very time-consuming, the only solution, that is, more practice, diligence knock. ! ! !