Ferdy Galema created NUTCH-1366:
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Summary: speed up indexing by eliminating the indexreducer
Key: NUTCH-1366
URL: https://issues.apache.org/jira/browse/NUTCH-1366
Project: Nutch
Issue Type: Improvement
Components: indexer
Reporter: Ferdy Galema
Fix For: nutchgora
Currently the indexer in Nutchgora consists of both mappers and reduces. But
the reduce code does not actually iterate over any (grouped/sorted) values. It
simply indexes individual key/value (String/Webpage) pairs. Therefore by moving
this indexing code to the mapper we can eliminate the reduce step therefore
making the indexing job much faster. (No more unnecessary spilling to
disk/network and no cpu wasted to sorting).
Note this is not (directly) applicable to trunk because trunk uses a quite
different approach. Different types of input are combined to a single value in
the reducer. Although I think it is possible to implement a similar
optimization I am not sure how to do this. So if anyone wants this for trunk
too feel free to implement a similar patch.
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