How to explain the big difference between memory and native store's sizes on disk in Sesame 2.7.7?

Question

I have a 2.9GB n-triples file, and I managed to load it in both a native sesame repository with (spoc, posc and ospc indexes) (let call it repo_native) and an in-memory sesame repository (let call it repo_memory). I've checked the on-disk size of both repositories in the directory ~/.aduna/openrdf-sesame/repositories and I was surprised that the directory repo_native take 1.8GB while the directory repo_memory only take 125MB.

I don't really have any clue about how to explain that. Is it that persistence in memory repository somehow also used native storage ?

Does some one have an explanation of such a difference in size?

Thanks in advance

Answer 1

There's not sufficient information here to diagnose the problem, but if you're uploading a 2.9GB file to a memory store, and the size of the memory store's storage dir is only 125M, that probably means that your data has not been persisted to disk. You likely have not configured your in-memory repository to sync to disk, or something has gone wrong during upload.

And no, the in-memory store does not use the native store's persistence mechanism, it has its own (far less sophisticated) persistence mechanism.