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Posted to mapreduce-user@hadoop.apache.org by Tim Robertson <ti...@gmail.com> on 2009/12/01 10:05:55 UTC
Simple normalizing of data
Hi all,
I am processing a large tab file to format it suitable for loading
into a database with a predefined schema.
I have a tab file with a column that I need to normalize out to
another table and reference it with a foreign key from the original
file. I would like to hear if my proposed processing is suitable:
Original file has: ID, .... Institution_Code ....
I need to normalize out the distinct Institution Codes to a separate
table and have an Institution_Code_ID in the original.
Job 1: Generate a file of Institution_Code:<ID>
Job 2: Use output of Job1 and using the row number as the
Institution_Code_ID, generate ID:rowNumber
Job 3: do a reduce side join of the original input and the output of
job 2 to generate
ID, ..... InstitutionCodeID ....
Job 1 output can then be used to populate the institutionCodes table,
and Job 3 will have the appropriate FK so can populate the main table.
Is this approach sane? Are there better approaches?
Many thanks,
Tim