Plenty of database workloads involve a lot of random I/O (e.g. anything that does an index lookup is typically doing random I/O). In theory, you should be able

Plenty of database workloads involve a lot of random I/O (e.g. anything that does an index lookup is typically doing random I/O). In theory, you should be able to tell the query optimizer about the relative costs of random vs. sequential I/O on your hardware, and have it adjust the costing of query plans accordingly (e.g. PG allows this, at any rate -- it might even be possible to infer that automatically, although not easy). Aside from the query workload, WAL is designed under the assumption that sequential writes are much cheaper than random writes, so you could imagine changing that when using SSDs...