[RESOLVED] Recommend database engine for Java program

[andrey_zh]

I think that you need to do some fundamental reading and research on databases before you start such a large project. I am not trying to be rude by saying this, but I think that your understanding of how these things work is far from where it should be for a project of this caliber.

You are generally right in evaluation of my skills. I have written only one (!) program that uses databases so far. (That was a Web-"page" on PHP and SQL database.) Basically I already know some things about Java (inheritance, generics and how to use it and so on). All of my programs written so far (in C, C++, Java, ...) are focused on algorithms. Suddenly I've realized that my programming skills are very far from real world. (I'm almost complete noob in networking and databases.)

I have never learned the inner working of the databases, but I believe that defragmentation and consolidation procedures could be done on a database file. Of course this will take time and write and erasure operations will ruin the order. But this should decrease database size and access time.

Imagine I have just 100MB of (any) data. If database file size is 1GB large, it will mean 900% overhead. It's very ineffective and unbelievable for me.

I think you are missing the point. Even if you only have 100 MB worth of data, trying to read and write to this file in as a single file DB will result in extremely slow CRUD operations.

A typical operation on a dictionary is reading.

An archived database is what it says - an archive; it isn't a usable database.

H2 database: http://www.h2database.com/html/featu...atabase_in_zip
Derby: http://db.apache.org/derby/docs/10.5...ploy11201.html