2011/11/17 Mattias Gaertner <[email protected]> > ** > > XML was invented to markup texts. Later programmers noticed that it is > also nice for config files. > > A few hundred MB of XML does not sound much compared to some big SQL > databases. But because it is "not that much" we want to search them in real > time (multiple queries taking less than half a second). That is not a > trivial task, not in a XML database, nor in a SQL database. > > > > Another important point is, that our data is hierarchical, has lots of > optional elements and attributes, the data model changes often and the data > is inconsistent. Using a SQL database for that would be stupid. > > After a year of programming with hierarchical structures I came to the > conclusion, that hierarchical databases are greatly underestimated. If your > SQL tables are not filled dense and/or if you have a lot of parent-child > relationships you should try them out. >
In 1990's there was hype about object DBs which would replace relational DBs. For some reason they disappeared. Now the existing object DBs are built on top of a relational DB, like the eMatrix I mentioned. I understood that XML is only the input data format for your DB. It is parsed into a memory structure and searches are done there. Then it could be called in-memory DB as well because the XML format is not the essential part. Juha
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