[dandrews]

Hierarchical and network DBMSs can scream, but you have to have a competent DBA curate the so-called "physical" relationships (indexes, record and index pointers, child record locality, block sizes, buffers, what-have-you) that support the logical views defined by the application schema. In either IMS or IDMS (where I have some experience) this can be a lot of work, done right. Measure, tweak, repeat. Those older DBMSs can be finicky, but properly monitored are great performers.

Conversely, a lazy DBA can cost you a lot of money. And lazy DBAs can be hard to identify - their domain is rather arcane after all.