Thomas, Not wanting to be a pedant, but you're mixing up Hashing (hash tables) and B-trees. B-Trees have O(log n) lookup time as you say, but hashing/hash tables/hash maps don't use B-Trees and in fact has O(1) lookup time. It takes just as long (in general case) to look up an item from 100 as it does from 100 000 000. See for example the entry on wikipedia for "Hash table".
The thought also crossed my mind that Dave could probably load up his entire database into memory and do all his operations using his own datastructures and algorithms (e.g. hash tables) and probably see all his problems disappear dramatically (especially since it's a single user application on a single PC) but of course this may (probably would) require major rework and so is probably unfortunately likely not going to happen... (Also, with the amount of growth per week, such a solution may not be scalable so is possibly not such a good idea from that point of view either... Dave, by how much does the database grow in size terms on a weekly basis, after compacting?) Anyway, best regards, Walter Prins Thomas Hruska wrote: >An associative hash is not the same thing as a cryptographic hash. An >associative hash is a data structure that implements a B-tree and thus >has O(log n) insert and search times. I've found them to be >resource-friendly and very high-performance (partly why they are used to >implement database indexes). > >Look up "stl map" on Google. I know it isn't Delphi, but that's the >data structure I'm referring to (and there are examples of how to use >stl map). Apparently JEDI has 'JclStrHashMap' which supposedly >implements a string-based associative hash (but I didn't see any example >code using it, but it should be similar to stl map). The following page >showed up when running a Google search for "JclStrHashMap": > >http://www.koders.com/delphi/fid02907AFF1132DABC5F684C899D2D01D7D72FEBEC.aspx > > > ----------------------------------------------------- Home page: http://groups.yahoo.com/group/delphi-en/ To unsubscribe: [EMAIL PROTECTED] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/delphi-en/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
