IE> Part of the problem with Elephant is that we currently create CLOS IE> objects in memory for every 'row' that is touched in a query (or IE> touched during an index operation). We have to de-serialize the IE> record, create an object, initialize any transient slots, etc. The IE> SQL engine, by contrast, can just keep track of a list of OIDs and IE> then count the size of the arrays that result from any joins. This is IE> a much cheaper set of operations per-row (i.e. per object). If we IE> only read OIDs into memory until the final step when we need to access IE> a slot, we can save quite a bit of the cost of object creation.
also backends which connect to database via a socket have considerable communication overhead, i think it's even larger than deserialization impact. IE> My hope is that a query system would implement this model properly. IE> Unfortunately, this will not happen soon, as much as I'm itching to do IE> it! OTOH it's fairly easy to make function that counts total number of entries in btree or in some range, at least it's easy with db-postmodern -- it just translates to COUNT(*) query. if there is such a big demand for this feature, we can just implement it as backend-specific advantage ^__^. _______________________________________________ elephant-devel site list elephant-devel@common-lisp.net http://common-lisp.net/mailman/listinfo/elephant-devel
