On Thu, Dec 11, 2008 at 6:09 PM, Robert Synnott <rsynn...@gmail.com> wrote:
> 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 This will not be a problem if the cleanup code is kept in a postgres transaction. The new slot update to :some-opt (after the delete) will result in a new entry in the blob table (from the stored procedure sp_ensure_bid). > > 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. It would be a fair punishment. The blob table and bids should be considered internal to db_postmodern, you are not supposed to mess with it or use these values in your application code. > > 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? Yes. /Henrik Hjelte _______________________________________________ elephant-devel site list elephant-devel@common-lisp.net http://common-lisp.net/mailman/listinfo/elephant-devel
