[Lazarus] Web development and XML database (Mattias)
nc-gaertnma at netcologne.de
Thu Nov 17 11:28:50 CET 2011
On Thu, 17 Nov 2011 11:38:25 +0200
Juha Manninen <juha.manninen62 at gmail.com> wrote:
> Thanks for the explanation.
> In essence it is a database optimized for reading but not writing.
> For updating the XML file contents there is no concurrency checks or atomic
At the moment the projects only edit the files by svn and other
In the later project phase editing will be added. Concurrency checks
are already there.
> That is fine with many use cases but for example e-commerce sites could not
> use it. They need safe transactions for user profile and sales action
> This is partly why the SQL databases are slow, they take care
> of concurrency also when data is updated.
That explains why writing is slow, not why reading and searching is
> Your solution could be used to provide fast access to a slow SQL DB data by
> generating data dumps eg. once a day.
Ehm, SQL is for relational databases. A XML database is hierarchical.
You can easily map data between those two, but their optimizations are
different. A simple search in a XML database often require complex
joins in SQL.
> eXist DB is made with Java. It would be interesting to compare how much
> their performance differs. Java has become very fast but it still hogs
> Good luck with the project!
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