DIY database?

[TheHimself]

I would like to have database capabilities in my programs but am not willing to use sqlite (blame the learning curve). Working with home-made databases whose columns have fixed length is easy however I don't know how to manage variable-length columns (for example the path to files in a database of files). If you want to modify such an entry don't you have to rewrite all the database contents following it? :(

A similar problem is erasing a record from a database. I do this by putting a null '\0' at the beginning of the line corresponding to the record.

[karlson]

I would like to have database capabilities in my programs but am not willing to use sqlite (blame the learning curve). Working with home-made databases whose columns have fixed length is easy however I don't know how to manage variable-length columns (for example the path to files in a database of files). If you want to modify such an entry don't you have to rewrite all the database contents following it? :(

A similar problem is erasing a record from a database. I do this by putting a null '\0' at the beginning of the line corresponding to the record.

Have you considered BerkeleyDB if you want to embed DB into your application?

[moldaviax]

could you use a csv file so that you could pick out variable length items between commas?

eg assuming you are using files, something like this...

Id, FileType, FilePath
1, jpg,/home/picture/pic.jpg
2, odf,/home/docs/doc.odf

so you can parse out the id, file type and path - in java easy to achieve with a StringTokenizer

M.

[gsmanners]

Easiest thing in the world:

http://docs.python.org/library/pickle.html

[TheHimself]

could you use a csv file so that you could pick out variable length items between commas?

eg assuming you are using files, something like this...

Id, FileType, FilePath
1, jpg,/home/picture/pic.jpg
2, odf,/home/docs/doc.odf

so you can parse out the id, file type and path - in java easy to achieve with a StringTokenizer

M.

Yes, of course. But what if you needed to modify one of those variable-length entries in the middle of the database? Does one have to rewrite the whole database file?
(There is a similar problem when editing in the middle of a text file. I don't know how text editors handle this. I guess for a small text file one can easily rewrite the whole file but for a huge database that may not be the best option.)

[moldaviax]

Personally I would persist with SQLLite or http://www.oracle.com/technetwork/java/javadb/overview/index.html

or use XML+XPATH :-)

However I think http://download.oracle.com/javase/tutorial/essential/io/rafs.html describes a java object (random access file) that might be of help if you want to build something from scratch. That does assume you are using Java...

M.