NoSQL

By Franck Pachot

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There are many NoSQL databases. And, because SQL is an ISO standard, “No SQL” also means “No Standard”. Many have a similar API and similar objects, but with completely different names. Today, NoSQL databases are used as an additional datastore for some well-defined use cases for which a hashed key-value store fits better than a relational table. And it quickly became “Not Only SQL” as it is complementary to RDBMS databases using SQL. But at the origin, the idea was to replace the RDBMS databases, refusing the SQL API, and then inventing a “No SQL” data store. When you want to replace something rather than proposing something new, you often adopt the same language to make it look similar. And this why, in my opinion we find some relational database terms like “Table” and “Index”. But they have a different meaning. Here is a dictionary where I try to explain the DynamoDB artifacts and differentiate from their Relational and SQL meaning.

By Franck Pachot

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That’s common to any data structure, whether it is RDBMS or NoSQL, indexes are good to accelerate reads but slow the writes. This post explains the consequences of adding indexes in DynamoDB.

By Franck Pachot

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In The myth of NoSQL (vs. RDBMS) “joins dont scale” I explained that joins actually scale very well with an O(logN) on the input tables size, thanks to B*Tree index access, and can even be bounded by hash partitioning with local index, like in DynamoDB single-table design. Jonathan Lewis added a comment that, given the name of the tables (USERS and ORDERS). we should expect an increasing number of rows returned by the join.

In this post I’ll focus on this: how does it scale when index lookup has to read more and more rows. I’ll still use DynamoDB for the NoSQL example, and this time I’ll do the same in Oracle for the RDBMS example.

By Franck Pachot

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I have written a few blog posts about some NoSQL (vs. RDBMS) myths (“joins dont scale”, “agility: adding attributes” and “simpler API to bound resources”). And I’ll continue on other points that are claimed by some NoSQL vendors and are, in my opinion, misleading by lack of knowledge and facts about RDBMS databases. But here I’m sharing an opposite opinion: SQL being user-friendly is now a myth.

By Franck Pachot

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By Franck Pachot

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J’essaie quelque chose de nouveau. Je publie beaucoup en anglais (blog, articles, présentations) mais cette fois quelque chose de 100% francophone. En sortant du confinement, on reprend les transports (train, voiture,…) et c’est l’occasion de se détendre en musique mais aussi de s’informer avec des podcasts. J’ai l’impression que c’est un format qui a de l’avenir: moins contraignant que regarder une video ou ou lire un article ou une newsletter. Alors je teste une plateforme 100% gratuite: Anchor (c’est un peu le ‘Medium’ du Podcast).

By Franck Pachot

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By Franck Pachot

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There are good reasons for NoSQL and semi-structured databases. And there are also many mistakes and myths. If people move from RDBMS to NoSQL because of wrong reasons, they will have a bad experience and this finally deserves NoSQL reputation. Those myths were settled by some database newbies who didn’t learn SQL and relational databases. And, rather than learning the basics of data modeling, and capabilities of SQL for data sets processing, they thought they had invented the next generation of persistence… when they actually came back to what was there before the invention of RDBMS: a hierarchical semi-structured data model. And now encountering the same problem that the relational database solved 40 years ago. This blog post is about one of those myths.

Here is my feedback after preparing and passing the AWS Database Specialty certification. There are tips about the exam but also some thoughts that came to my mind during the preparation when I had to mind-shift from a multi-purpose database system to purpose-built database services.

John Beresniewicz presents this lightning talk during the OTW 2018 unconference in San Francisco.