November 2015
Beginner to intermediate
248 pages
5h 24m
English
Content preview from Learning CouchbaseBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Custom reduce functions
Why do we need custom reduce functions? Sometimes, the built-in reduce function doesn't meet our requirements, although it will suffice most of the time.
Custom reduce functions allow you to create your own reduce function. In such a reduce function, output of map function goes to the corresponding reduce function group as per the key of the map output and the group level parameter. Couchbase ensures that output from the map will be grouped by key and supplied to reduce. Then it's developer's role to define logic in reduce, what to perform on the data such as aggregating, addition etc.
To handle the incremental MapReduce functionality (that is, updating an existing view), each function must also be able to handle and consume ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.