Hi Tomas,
Its related to content repository. There are some possibilities that runs a schedule job using the content revision. From what I remember there is scheduled job that cleans out the file system of CR files, although I think it runs only once a day. Another scheduled job is the search indexer, which runs about a few hundred a day I think.
Anyway you might want to look at what context is the query being used, the query is a bit general.
