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Diffstat (limited to 'docs/programming-guide.md')
| -rw-r--r-- | docs/programming-guide.md | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/docs/programming-guide.md b/docs/programming-guide.md index 2443fc29b4..6486614e71 100644 --- a/docs/programming-guide.md +++ b/docs/programming-guide.md @@ -886,7 +886,7 @@ for details. <td> <b>groupByKey</b>([<i>numTasks</i>]) </td> <td> When called on a dataset of (K, V) pairs, returns a dataset of (K, Iterable<V>) pairs. <br /> <b>Note:</b> If you are grouping in order to perform an aggregation (such as a sum or - average) over each key, using <code>reduceByKey</code> or <code>combineByKey</code> will yield much better + average) over each key, using <code>reduceByKey</code> or <code>aggregateByKey</code> will yield much better performance. <br /> <b>Note:</b> By default, the level of parallelism in the output depends on the number of partitions of the parent RDD. |