Re: Migrate 200 Million of rows

Yes, you are wrong, it is nothing like analogue amplification or attenuation.
"Compression" is probably a poor choice of word, but it is now so established that we're stuck with it. At the simplest level of explanation, data is represented in a different way that is more efficient in the use of bits (and bytes). Suffice to say that "arithmetic" is performed on the data, the result of which is a representation that is more efficient in its bit usage. The arithmetic is "reversible" so that the original data can be recreated. The nature of the arithmetic is such that applying it to the results obtained from a previous "compression" will not yield a further reduction in size, in fact it will typically produce a larger output.

I hate to admit how long ago it was that someone had me nearly convinced that he was working on a compression algorithm that would reduce the size of an infinitely large file to a single bit. He said it worked, but the decompression code still had bugs.

That and his perpetual motion machine (-:

\R

Ryan Gaffuri wrote:
>
> vslabs_at_onwe.co.za (Billy Verreynne) wrote in message news:<1a75df45.0307282103.1b5c53cf_at_posting.google.com>...
> > rgaffuri_at_cox.net (Ryan Gaffuri) wrote
> >
> > > which compression program are you using? TAR? I was told its slow.
> >
> > TAR does not do compression - except for the Linux version that has
> > Lempel-Ziv filtering built in (you use that with the -z/-Z switches
> > for compress/gzip).
> >
> > The compression program (standard on all Unix flavours AFAIK) is
> > called compress. And as I said, it uses an adaptive Lempel-Ziv coding
> > scheme.
>
> i dont know anything about compression algorithms. ive always wanted
> to get a high level explanation of how they actually 'compress'
> something. Im assuming its similiar to how voice is amplified when you
> speak in the phone. samples are taking and applied from there.
>
> or am I wrong?
Received on Thu Jul 31 2003 - 06:35:54 CDT