Not everybody works at eBay, GMail or Facebook scale.<p>Most applications fit very well in a single server. For example, Stack Overflow runs on a single instance of SQL Server, replicated to a slave in another data center. In such a case, the convenience of joins and transactions is priceless.<p>And even at scale, it makes sense to rely on joins and transactions. The perfect example is AdWords that runs of F1 and Spanner:<p>&quot;Our users needed complex queries and joins, which meant they had to carefully shard their data, and resharding data without breaking applications was challenging.&quot;<p><a href="http:&#x2F;&#x2F;static.googleusercontent.com&#x2F;media&#x2F;research.google.com&#x2F;fr&#x2F;&#x2F;pubs&#x2F;archive&#x2F;41344.pdf" rel="nofollow">http:&#x2F;&#x2F;static.googleusercontent.com&#x2F;media&#x2F;research.google.co...</a>