🚀 go-pugleaf

On 13 Nov 90 20:58:19 GMT, peter@ficc.ferranti.com (Peter da Silva) said:

peter> Piercarlo Grandi:
pcg> Ah no, this cannot pass. Lists and trees are *implementations*, and
pcg> when you draw them you draw specific encodings of such
pcg> implementations.

peter> David Gudeman:
gudeman> No, this cannot pass.  Lists and trees are mental structures
gudeman> that humans use to visualize things.

peter> While I'm generally in the bit-bangers camp, I must agree with
peter> Piercarlo here.

I am a bit banger too, mate...

peter> Lists, trees, tries, and so on are methods of implementing these
peter> databases in efficient ways. There's nothing fundamental about
peter> them. [ ... ] The problem is that there's no language I know of
peter> that really lets you get away with writing your program in terms
peter> of relations and get within an order of magnitude in speed of a
peter> well-written lower level implementation.

As to this I have good news! DBMSes and 4GLs are often (anectodal but
frequent evidence) impressively *faster* than any ad-hoc program that
does the same. NOTE: *the same*, not similar but much much simpler.

If you are manipulating large masses of data in complicated ways, which
is most people want to do, a well written DBMS is going to be way ahead
of any well written lower level solution. Notice that you *can* for a
very important problem outrun a well written DBMS with diabolically well
written low level code, but this is a rare case.

The same applies for example to sort utilities -- normally it takes a
lot of effort to beat a well written generic sort utility on any system
I know of.

The database approach is also being applied to in-memory databases, both
relational or OO. They are usually well within an order of magnitude of
using explicit ad hoc trees and lists, and may be even faster, if (and
again very few are well written) they pay attention to paging issues,
which normally even well written tree and list packages ignore.

	For example: an incore database may use B+ trees, which have an
	immensely better, if its blocks are suitably aligned and sized,
	locality profile than most garden variety trees.

Again, many programs, either in-memory or on-disk, are sophisticated and
large enough to be considered minro DBMSes. Too bad they are not
designed as such...
--
Piercarlo Grandi                   | ARPA: pcg%uk.ac.aber.cs@nsfnet-relay.ac.uk
Dept of CS, UCW Aberystwyth        | UUCP: ...!mcsun!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk