Umair Shahid: Choosing the Right PostgreSQL Partition Key

Partitioning gets sold as a performance switch. You flip it on a big table, and the slow queries get fast. Most of the time, that is exactly what happens. But there is a version of this where you do all the work, split a huge table into clean partitions, and the slow queries stay exactly as slow as they were. The table is partitioned. Nothing got better. When that happens, the partition key is almost always the reason. Partitioning mechanics are the easy part, and PostgreSQL handles them well. Choosing the column to partition on is the decision that carries the weight, and it is the one you mo