Why haven the ODBMS companies overtaken the RDBMS companies?
RDBMSs perform perfectly adequately for many types of applications, particularly in the regular Information Technology domain. ODBMSs target a narrow range of applications, so the potential market size is smaller. A loose analogy is that RDBMS companies are like the manufacturers of internal combustion engines and the ODBMS companies are like the manufacturers of jet engines. The two technologies service different markets, but there is a small degree of overlap. In general, ODBMSs can service all of the applications that an RDBMS could be used for, but the reverse is not true, at least not with anything like the same performance or ease. The RDBMS companies also have a 15 year lead, so they have a well established and fairly loyal customer base, often with site licenses that conceal the real costs of ownership. Companies have invested a lot of resources and money to learn how to run their RDBMS technology, so they are slow to change technologies. ODBMSs are generally easier to learn an
