David Parks created HADOOP-9262:
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Summary: Allow jobs to override the input Key/Value read from a
sequence file's headers
Key: HADOOP-9262
URL: https://issues.apache.org/jira/browse/HADOOP-9262
Project: Hadoop Common
Issue Type: Improvement
Components: io
Affects Versions: 1.0.3
Reporter: David Parks
Priority: Minor
There's no clean way to upgrade a sequence file when the model objects in an
existing sequence file change in the development process.
If we could override the Key/Value class types read from the sequence file
headers we could write jobs that read in the old version of a model object
using a different name (MyModel_old for example) make the necessary updates,
and write out the new version of the object (MyModel for example).
The problem we experience now is that we have to hack up the code to match the
Key/Value class types written to the sequence file, or manually change the
headers of each sequence file.
Versioning model objects every time they change isn't a good approach to
development because it introduces the likelyhood of less maintained code using
an incorrect, old version of the model object.
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