> joins allow you to make the relationship you want at query time And the price you pay for that is speed. Direct arc traversal is always O[1]. Querying is O[a

> joins allow you to make the relationship you want at query time And the price you pay for that is speed. Direct arc traversal is always O[1]. Querying is O[all_over_the_map] and all traversal in an RDBMS is essentially querying. But your point is well taken: Hardcoded arcs move the speed problem to update time. However modern graph databases use a number of techniques to mitigate this problem like indirect pointers and reified relation objects. Yes, this slows things down to something like O[2] (which is of course the same thing as O[1] but I'm pointing out that it's about half as fast) but it preserves traversal speed predictability (minimizing traversal variance) while also allowing update flexibility. At the same time modern RDBMSs optimize candidate key traversal queries to the point that they're essentially O[1] too so it's kind of a potato/potahto situation.