[fpc-pascal]Databases and FPC
prologic at prologitech.com
Wed May 7 06:32:20 CEST 2003
On Tue, May 06, 2003 at 06:06:53PM +0200, Michael.VanCanneyt at Wisa.be wrote:
> On Wed, 7 May 2003, James Mills wrote:
> > On Mon, May 05, 2003 at 01:36:03PM +0200, Peter Brooks wrote:
> > > Use a KSAM/ISAM [Keyed/Indexed Sequential Access Method] file. They are much
> > > faster than databases, particularly relational ones and very easy to code
> > > up.
> > >
> > > All you need to do is make the size of the file around 40% bigger than you
> > > expect it ever to be (and if it gets up to 50% then rebuild an re-populate
> > > it) then produce a hash number from the names and write to that address. You
> > > have to have a good hash algorithm (tons about) and a policy for migrating
> > > secondaries but it is all fairly straightforward. If your records are large
> > > you might have two files, one for the keys and one for the data, then you
> > > don't even need a hash key, you just insert the names in batches (say each
> > > evening or every hour if it is really busy) where you re-sort the whole key
> > > file and add the items in alphabetical order, a quick sort [maybe literally
> > > if you like it] will yield the name and you simply add the records to the
> > > end of the other file.
> > This particular method you are talking about, KSAM/ISAM. Could you point
> > me to some usefull tutorials on the web that explain this fairly well in
> > programming terms (perhaps even in pascal) ?
> You might try to use the gdbm units provided standard with Free Pascal.
> There are examples included.
> fpc-pascal maillist - fpc-pascal at lists.freepascal.org
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