[FLINK-758] Add count method to DataSet and implement CountOperator

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 0.7.0-incubating
• Fix Version/s: pre-apache
• Component/s: API / Scala
• Labels: github-import
• Assignee: Unassigned
• Reporter: GitHub Import
• Created: 09/Jun/14 12:53
• Updated: 28/Feb/19 14:29
• Resolved: 03/Feb/15 15:11

Description

At the request of @twalthr. This is the count operator I've implemented some time ago to get the to know the new Java API. It introduces `DataSet.count()`, which is executed as a map (to ones) and reduce (sum up the ones). I initially didn't do the PR, because of the following problem: empty DataSets don't work as the first map won't have any input to operate on.

If more people think that we should include this operator we can think about a possible solution to the problem.

---------------- Imported from GitHub ----------------
Url: https://github.com/stratosphere/stratosphere/pull/758
Created by: uce
Labels: enhancement, java api,
Milestone: Release 0.6 (unplanned)
Created at: Tue May 06 10:42:33 CEST 2014
State: open