You make a good point about knowing your database technology. For me the takeaway from the article is "know your database technology and your data" especially i

You make a good point about knowing your database technology. For me the takeaway from the article is "know your database technology and your data" especially if you plan to get big. The original post refers to RDBMS and seems to be largely based on MySQL/InnoDB experience. InnoDB clusters on the primary key and copies primary key values into secondary indexes, so scattered writes and exploding secondary indexes are as well-known problem if you use UUIDs as the primary key on MySQL. Another well-known issue is that UUIDs can lead to random scattering of reads which chew up space in the buffer pool. That said, other RDBMS types don't necessary have the same problems. SQL server can cluster on non-primary key columns or not cluster at all (heap organization). In the latter case secondary indexes on the table use row IDs (RIDs) to refer to rows from the index. Using UUID as a primary key does not inexorably entail performance problems though it might if you made bad choices about indexing. It seems to me people sometimes make a bigger deal of UUIDs and DBMS than is really called for. Badly chosen surrogate keys or time-series clustering can lead to performance problems that are just as severe depending on your access patterns. There are perfectly reasonable workarounds for UUID issues like using integer surrogate keys, which RDBMS support quite well. To use them effectively though you need to spend time to understand your DBMS technology and implementation choices thoroughly. A lot of people skip this step.