MySQL and Postgres both support it; that's a huge percentage of what most devs are ever going to encounter. MSSQL and Oracle may do so as well, but I'm not fami

MySQL and Postgres both support it; that's a huge percentage of what most devs are ever going to encounter. MSSQL and Oracle may do so as well, but I'm not familiar with those beyond some trivial usage. More to the point, this lack of knowledge will almost certainly drive people to over-index, which harms performance.