50 Shades of NULL — Subtitled “How a Billion Dollar Mistake has Been Stalking a Whole Industry for Decades”, this is a look at the history of nil/null values and how NULL works in SQL.

What NoSQL Solution Should You Choose? — Quick summaries of MongoDB, Elasticsearch, OrientDB, Hadoop, and Cassandra, focusing on what each can and can’t do.

Heroic: A Time Series Database from Spotify — Heroic is an open-source monitoring system originally built at Spotify to address the problems being faced with large scale gathering and near real-time analysis of metrics.

Have you got SQL fingers? — Watch these free SQL Prompt tips videos for SQL writing hints from top SQL Server MVPs. SQL Prompt is the SQL code productivity add-in for SQL Server Management Studio and Visual Studio. Find out how easily you can write SQL.

Organize Complex Queries Using SQL's 'WITH' — SQL:1999 introduced the ‘WITH’ clause to define “views” within queries. These with-queries are only visible in a single statement and can be used to improve the structure of this statement without polluting the global namespace.

Apache Geode: A Distributed, In-Memory Low Latency Database — The Apache-incubated open source version of a commercial in-memory database called GemFire.

HyperLogLog in Pure SQL — Hyperloglog is a very interesting algorithm and you can have an extremely efficient version directly in Postgres. And if you’re not up for building and pulling in your own extensions here’s a raw SQL implementation of it.

10 Use Cases Where NoSQL Will Outperform SQL — Written by a director at Couchbase.