old databases may take up too much space

[coldnebo]

using DataHut for logging and analysis, I've noticed that sometimes the sqlite database file grows big and stays big no matter how much record culling is done.

in this case, a method like dw.compact! would be useful. This could call sqlite's VACUUM statement like this:

@db.run "VACUUM"

Also, perhaps the db should be exposed to people who need to maintain the sqlite db directly? (previously I had tried to hide the db as I wanted the primary interaction to be through data_hut and perhaps the records themselves, but there are certain meta operations (like VACUUM) that are made easier by having a public handle to the db as well.