Database Reference
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[ 64 ] In some applications, it's common for some of the input to already be sorted, or at least partially sorted.
For example, the weather dataset is ordered by time, which may introduce certain biases, making the Ran-
domSampler a safer choice.
[ 65 ] For simplicity, these custom comparators as shown are not optimized; see Implementing a RawCompar-
ator for speed for the steps we would need to take to make them faster.
[ 66 ] If you are using the old MapReduce API, the same methods can be found in org.apache.ha-
doop.filecache.DistributedCache.
[ 67 ] In Hadoop 1, localized files were not always symlinked, so it was sometimes necessary to retrieve local-
ized file paths using methods on JobContext . This limitation was removed in Hadoop 2.
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