I think 25% bandwidth savings is certainly considerable, especially for
people running full nodes in countries like Australia where internet
bandwidth is lower and there are data caps.

I absolutely would not dismiss 25% compression. gzip and bzip2 compression
is relatively standard, and I'd consider the point of implementation
complexity tradeoff to be somewhere along 5-10%.

On Tue, Nov 10, 2015 at 8:04 AM, Bob McElrath via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> I would expect that since a block contains mostly hashes and crypto
> signatures,
> it would be almost totally incompressible.  I just calculated compression
> ratios:
>
> zlib    -15%    (file is LARGER)
> gzip     28%
> bzip2    25%
>
> So zlib compression is right out.  How much is ~25% bandwidth savings
> worth to
> people?  This seems not worth it to me.  :-/
>
> Peter Tschipper via bitcoin-dev [bitcoin-dev@lists.linuxfoundation.org]
> wrote:
> > This is my first time through this process so please bear with me.
> >
> > I opened a PR #6973 this morning for Zlib Block Compression for block
> > relay and at the request of @sipa  this should have a BIP associated
> > with it.   The idea is simple, to compress the datastream before
> > sending, initially for blocks only but it could theoretically be done
> > for transactions as well.  Initial results show an average of 20% block
> > compression and taking 90 milliseconds for a full block (on a very slow
> > laptop) to compress.  The savings will be mostly in terms of less
> > bandwidth used, but I would expect there to be a small performance gain
> > during the transmission of the blocks particularly where network latency
> > is higher.
> >
> > I think the BIP title, if accepted should be the more generic, "Support
> > for Datastream Compression"  rather than the PR title of "Zlib
> > Compression for block relay" since it could also be used for
> > transactions as well at a later time.
> >
> > Thanks for your time...
> > _______________________________________________
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> > bitcoin-dev@lists.linuxfoundation.org
> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
> >
> >
> > !DSPAM:5640ff47206804314022622!
> --
> Cheers, Bob McElrath
>
> "For every complex problem, there is a solution that is simple, neat, and
> wrong."
>     -- H. L. Mencken
>
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