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- Xref: sparky comp.databases:6488 bit.listserv.dbase-l:892
- Path: sparky!uunet!munnari.oz.au!mel.dit.csiro.au!yarra!pta!g2syd!michaelh
- From: michaelh@g2syd.genasys.com.au (Michael Haldey)
- Newsgroups: comp.databases,bit.listserv.dbase-l
- Subject: Re: Clipper: Backup/Restore routines for BIG files...
- Message-ID: <1992Sep2.001249.4787@g2syd.genasys.com.au>
- Date: 2 Sep 92 00:12:49 GMT
- References: <1992Sep1.114959.11104@cs.tu-berlin.de>
- Organization: Genasys II, Sydney, Australia
- Lines: 41
-
- In article <1992Sep1.114959.11104@cs.tu-berlin.de> schli@cs.tu-berlin.de (Wolfram Schlickenrieder) writes:
- >
- > Hi there...
- >
- > I'm stuck: I wanted to write a backup & restore routine for an
- > application I wrote before, but I have got a few data bases
- > which are HUGE (2-4MB) and therefore won't fit on a single
- > disc. Has anyone out there done that before from within a
- > Clipper application (without using "run backup ..." of
- > course)?
- >
- > Any help is appreciated...
- >
- > ...Wolfram
-
- This is how I did it.
- I read .dbf file as a binary file and then copied it to several
- sequentional floppy disks with arch file names <root_name>.00; ...01 etc.
- In the beginning there was a binary header with the length of the file,
- original name, 'continue' flags etc.
-
- This could be done within the Clipper application. But there were some
- problems: 1. you can not provide error (i.e. CRC) control; 2. you can
- not realize which type of floppy disk do you have; 3. it is quite slow,
- because you can not control the buffering.
-
- At the end we switched to the C routine which did all the things. By the
- way, if you use a packing program ( pkzip or similar ) it will reduces
- your .dbf to 30-70% of the original size. It is especially important if
- you have a 'rare' filled .dbf with 0's or blanks (in one of my application
- pkzip reduced file from 200k to 15k). (Of course, you have to either buy
- the program for every copy you sell or write a clone using published
- formats of the packed file).
-
- My 0.02
- Michael
- --
- Michael Haldey | Genasys II Pty Ltd
- | 13th Level, 33 Berry St, North Sydney, NSW, Australia
- | Phone: +61-2-954-2878 (-9930 FAX)
- | Internet: michaelh@g2syd.genasys.com.au
-