2008/12/11 Henrik Hjelte <hen...@evahjelte.com>: > I agree with Alex, just one perhaps obvious comment: I would have one > transaction around cleaning up one blob-id, not a big transaction > around cleaning up the whole blob table. If you do several > transactions it doesn't lock up much, so it > should be able to execute at the same time as a database is in production. > > I hope your code can be added to the postmodern backend. > > Thanks, > Henrik > > ________
I can certainly provide it as a contrib, but as it stands, it is not useful in all circumstances; it keeps track of the live bids using a huge array of booleans, and for a sufficiently big database memory would become a problem. It suits my database, however. I have two other minor worries about this technique. First, it would seem possible that if, say, we have slot1 in object1 which was set to :some-opt at some time in the past, but is now totally unused by any object, the blob row containing that would be considered dead; if someone comes along while the cleanup is running and sets some slot to :some-opt, then it will be in use again, but potentially get deleted anyway, because it will have already been deemed dead. This isn't really a problem for me; due to the nature of my dataset the chances of this happening are remote, but I can imagine it'd be an issue for some people. Secondly, there's the possibility that somebody could put a bid in, say, a serialized list. This would NOT be detected by the procedure I've outlined, and the thing with that bid would be deleted if not referred to elsewhere. Again, this isn't a problem for me, but somebody else might potentially be doing it. Beyond those, though, in the normal case I am correct to assume that a blob entry can be considered totally unused if not referred to in either slots or any tree? Thanks Rob _______________________________________________ elephant-devel site list elephant-devel@common-lisp.net http://common-lisp.net/mailman/listinfo/elephant-devel
