Florian Lindner wrote:
Hello,
I'm searching for the best concept of how to use and save hierarchical data.
I have a structure like PC file system with meta data. There a folder objects
and files objects of different types. Every object have data like
permissions, date and author. And they have type-specific data fields like
resolution (of an image type) or location (of an meeting type) or ingredients
(of an recipe type).
What is the best way to store that kind of data? What database is
recommendable? What concepts of persistance? Or not using managed persistance
and do it manually?
If you want to do it manually, a hierarchical tree can be represented by
just one table:
CREATE TABLE tree (
id INTEGER PRIMARY KEY,
parent_id INTEGER
);
With managed persistence, be carefull not to configure it to load the
entire tree at once.
As for a DB, any decent relational DB will do.
Nix.
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