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Tag Archives: NoSQL

Optimistic locking retry with MongoDB

In my previous post I talked about the benefit of employing optimistic locking for MongoDB batch processors. As I wrote before, the optimistic locking exception is a recoverable one, as long as we fetch the latest Entity, we update and save it. Because we are using MongoDB we don’t have to worry about local or XA transactions. In a future ...

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MongoDB optimistic locking

When moving from JPA to MongoDb you start to realize how many JPA features you’ve previously taken for granted. JPA prevents “lost updates” through both pessimistic and optimistic locking. Optimistic locking doesn’t end up locking anything, and it would have been better named optimistic locking-free or optimistic concurrency control, because that’s what it does anyway. So, what does it mean to ...

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Using Sorted Sets with Jedis API

In the previous post we started looking into Jedis API a Java Redis Client. In this post we will look into the Sorted Set(zsets). Sorted Set works like a Set in the way it doesn’t allow duplicated values. The big difference is that in Sorted Set each element has a score in order to keep the elements sorted. We can see ...

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Crawling the Web with Cassandra and Nutch

So, you want to harvest a massive amount of data from the internet?  What better storage mechanism than Cassandra?  This is easy to do with Nutch. Often people use Hbase behind Nutch.  This works, but it may not be an ideal solution if you are (or want to be) a Cassandra shop.   Fortunately, Nutch 2+ uses the Gora abstraction layer ...

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Getting Started With Jedis

Hi, these days I started looking into Redis. I’ve heard a lot about it so I decided to have a try. Redis is defined in its websites as “an open source, advanced key-value store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets and sorted sets“. We can find very good ...

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The 10 Most Popular DB Engines (SQL and NoSQL)

How to objectively measure the popularity of a DB engine? Good question! And there’s an Austrian company (Solid IT) who claims to have the answer. The company focuses on “Big Data und NoSQL”, but this focus does not seem to have biased the result of the measurement. Among the top 10 database engines, there is only MongoDB, which is not ...

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The Premature Return to SQL

In online communities, the NoSQL topic (much like the ORM topic) is a guarantee to stir emotions. Many emotions are stirred by evangelists on either side for ideological or marketing reasons. Here’s an interesting post by Alex Popescu, a passionate NoSQL and polyglot persistence evangelist, claiming that the recent trend to return to SQL is premature:         ...

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