Mikio Hirabayashi has built a very nice API called 'QDBM'.
see also http://qdbm.sourceforge.net/benchmark.pdf
QDBM is well known in the Unix world, but has been ported to Win32. Practically, it is a disk-based Hashtable + Binary tree + inverted list package. QDBM offers many solutions called 'depot', 'curia', 'villa', 'odeum' and is well worth a look if you want to manage large amount of data.
In the enclosed project, you'll find a small 'depot' wrapper for Visual Prolog.
The example creates 1 000 000 (key, values) and then ask for 1 000 000 keys at random. All the key/values are stored on disk in a single file.
Using a collection of instances of the visual prolog class 'depot', you can manage a very large hashtable on disk.
I do not provide a full documentation since the real documentation can be found on the above web site. Only the port of depot is functional in this lib.
I tried to simplify the use of this lib as much as possible, and tried not to get too far away from the original API syntax :
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NewDepot = depot::new("dtest"), % create a depot db NewDepot:dbopen("create"), % open it (create mode) NewDepot:dbput_string(Key, Value), % put a key,value NewDepot:dbclose(), % close the file
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ReadDepot = depot::new("dtest"), % ReadDepot:dbopen("read"), % open it in read mode Value = ReadDepot:dbget_string(Key), % tries to find the value for a key, fails if no value ReadDepot:dbclose(), %
The project doesn't include a copy of qdbm (because of the allowed posting size); I encourage you to download the most up-to-date version on the site above. It is provided under the GNU Lesser GPL.
Just copy the three following files into your exe directory :
you will find the package there :