This is the question. Give just one reason you believe why have OODB unsuccessful or the reasons systems nowadays still use relational databases.

The primary reason is SQL. Its very helpful to have the ability to use data from the database in other contexts outdoors from the application and frequently with object databases the information is saved inside a format that can't be easily queried. Having a relational database the information can end up part of an information warehouse, for example, or simply queried by sys admins etc.

Are we able to answer more often than once? One more reason is the fact that relational DB's possess a strong foundation in mathematics: from the phrase a relation, through towards the normal forms, the idea is reliable. It is a fact the relational model doesn't map well to OO, but IMHO the advantages and stability of this model over-shadow the mapping problem.

I believe it is because "object databases" are fixing an issue that (almost)nobody really has. For straightforward persistence of object graphs, the serialization included in most OO conditions is "adequateInch. If you wish to do sophisticated procedures on the subset of the data, a relational database and SQL really are a perfect fit.

Apart from some fringe programs (enormous object graphs that can not be stored in memory, however for that the associations don't simplify lower well for RDBMS use), there really is not any requirement for these power tools.

Simply because OODB aren't the mainstream we ought to consider the achievements they have had. Cache and Zope are generally broadly used (relatively) but could be considered effective by some standards.

Possibly the greatest reason why OODB haven't taken hold significantly is due to the prosperity of the hybrid object-relational systems that take the majority of the potential marketshare from OODB: PostgreSQL and Informix.

I understand that this doesn't directly answer the question but it's, I believe, part of the process. Overall, though, I believe that momentum and also the heavily ingrained thoughts supporting relation databases allow it to be a hardship on individuals to switch. Presently the DB profession is trained almost solely in relational theory making your DB professionals very thinking about staying away from OODB and academia shows DB theory for professionals almost solely on relational.

Until large, corporate DBAs and mainstream professors and curriculum and turning out staff beyond designers ready to handled OODB Personally i think that it's unlikely to determine mass appeal regardless of how good it's in the development side.

Well, it's strange is not it? There's this type of push towards domain driven design because the zenith of object orientated analysis and design, and you will find enterprise designs available to leverage ORM systems to persist our objects. It simply makes total sense in my experience when the application DESIGN is object orientated and domain focussed in mind, that the OODB will greatly benefit the application.

Besides the issues around maturity and uptake, from the philosophical perspective an OODB seems advantageous or perhaps an OO application. not needing to maintain that mapping layer to begin with)

But look, should you aren't doing domain drive design and employ objects as data objects and much like your saved procs, then you are not necessarily getting it)

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RDBMs are (built on the strong theoretical foundation, happen to be looking for a significantly extended period, can model data more faithfully than OODBs oftentimes, may be used by more DBAs than OODBs). That's one reason as a relational tuple.

Basically can amplify Phil's point: the standardization of SQL. OODB's have attempted query languages for example OQL however they never appeared to follow along with a genuine standard. Also the standard from the query languages were suspect, perhaps because of insufficient standardization. Standards promote competition, which spawns quality.

That, and o/r-mappers. Through them, the main difference to true OO-DBs becomes way more compact, as the aforementioned benefits stay valid.