[Lazarus] Web development and XML database (Mattias)

Juha Manninen juha.manninen62 at gmail.com
Thu Nov 17 15:58:11 CET 2011

2011/11/17 Mattias Gaertner <nc-gaertnma at netcologne.de>

> **
>   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

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