Data in the Cloud: SQL? NoSQL!


In recent years, one trend has become increasingly popular: NoSQL Databases. Databases built without relations, but made for high scalability. But is it really that “good” to go for NoSQL Databases? Doing so means removing the consistency that SQL Databases offers. Isn’t that a big tradeoff or is it worth going for more NoSQL Databases? What are the opportunities, advantages of NoSQL and why should you definitley keep an eye onto it? Join me for a tour on NoSQL. A world without relations, no joins and pure scalability!

A key disadvantage of SQL Databases is the fact that SQL Databases are at a high abstraction level. This is a disadvantage because to do a single Statement, SQL often requires the data to be processed multiple times. This, of course, takes time and performance. For instance, multiple queries on SQL Data occur when there is a ‘Join’ operation. Cloud Computing environments need high-performing, and highly scaleable databases.

Normally, SQL Databases have the advantage over NoSQL Databases to have better support for Business Intelligence. In most cases, Business Intelligence is not necessary in NoSQL Databases. If we look at the big Platforms in the Web like Facebook or Twitter, there are some Datasets that do not need any relations. The risk in that is the fact that there might be some kind of “inconsistency” across various  tables. The challenge for NoSQL Databases is to keep the data consistent. Imagine the fact that a user deletes his or her account. If this is hosted on a NoSQL Database, all the tables have to checked for any data the user has produced in the past. With NoSQL, this has to be done by code.

A major advantage of NoSQL Databases is the fact that Data replication can be done more easy then it would be with SQL Databases. As there are no relations, Tables don’t necessary have to be on the same servers. This allows a NoSQL Database a much more performant way to partition the data. This fact also applies to tables itself. If a table gets very big, this Table can be distributed over various servers easily. Again, this allows better scaling than SQL Databases. Don’t forget: scaling is one of the key aspects in Cloud Computing environments.

To fully understand why NoSQL Databases will be the future for Cloud Computing data, it is important to understand how Cloud Computing works. Cloud Computing Plattforms are made for a great number of people and potential customers. This means that there will be millions of queries over various tables, millions or even billions of read and write operations within seconds. SQL Databases are built to server another market: the business intelligence one, where less queries are executed.

Another disadvantage of SQL databases is the fact that there is always a schema involved. Over time, requirements will definitely change and the database somehow has to support this new requirements. This can lead to serious problems. Just imagine the fact that your application now needs two extra fields to store data. Solving this issue with SQL Databases might get very hard. NoSQL databases support a changing environment for data and are a better solution in this case as well.

However, it is up to the Use-Case to identify if you want a NoSQL approach or if you better stay with SQL

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Published by

Mario Meir-Huber

I work as Big Data Architect for Microsoft. With this role, I support my customers in applying Big Data technologies - mainly Hadoop/Spark - for their use-cases. I also teach this topic at various universities and frequently speak at various Conferences. In 2010 I wrote a book about Cloud Computing, which is often used at German & Austrian Universities. In my home country (Austria) I am part of several organisations on Big Data.

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