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Date: Sat, 31 Jan 2015 18:04:52 +0100
Message-ID: <CANEZrP3+ca9Bumv=-2ot7T5s6cvGhN_dMqYmsxP7qP1V0WV4qg@mail.gmail.com>
From: Mike Hearn <mike@plan99.net>
To: Angel Leon <gubatron@gmail.com>
Content-Type: multipart/alternative; boundary=e89a8f3ba0853f4236050df5b8a7
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Is there a way to estimate the maximum
 number of transactions per minute Bitcoin can handle as it is today?
Precedence: list

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>
> "Alipay handled up to 2.85 million transactions per minute, and 54 percent
> of its transactions are made via mobile device."
>

I know China is a very big place but even so - 47,500 transactions per
second would be almost quintiple what Visa handles across the entire world.
With only 300 million users and primarily online usage (?) this claim feels
a little suspect to me.

Given the wording "up to 2.85 million" I wonder if that is some freak spike
caused by people's behaviour being synchronised externally (e.g. a fixed
start time for the sale that people are waiting for). It's hard to imagine
that they sustained anything close to that for the entire day.

So this is really a discussion about peak performance.

If you average every transaction around 250 bytes, then you'd need ~15
> Gigabytes per block to be broadcast and hashed by all the full nodes every
> 10 minutes, eating good 2Tb of storage daily... do miners have enough
> bandwidth and CPU power to handle this?
>

There's a discussion of such things here that might be useful:

https://en.bitcoin.it/wiki/Scalability

It discusses various optimisations, like not actually sending tx data twice.

I wouldn't worry about it too much. It took decades for Visa to even
approach 10,000 txns/sec. PayPal, I believe, still "only" handles a few
hundred. And those services had the benefits of minimal competition,
working in people's local currencies, integrated dispute mediation and not
representing any real threat to the political status quo. Bitcoin isn't
going to be needing to handle Alipay's level of traffic any time soon.

Frankly, scaling is a nice problem to have, it means you're popular. It'd
be a mistake to just blindly assume Bitcoin will take over the world.
Growing market share is difficult. Worry more about how to get 300 million
crazy users than the precise broadcast protocol that'd be needed to handle
them ;)

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<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><blo=
ckquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left=
-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;paddi=
ng-left:1ex"><div dir=3D"ltr"><div><span style=3D"color:rgb(0,0,0);font-fam=
ily:NHG,&#39;Helvetica Neue&#39;,Helvetica,Arial,sans-serif;font-size:14px;=
line-height:20px">&quot;Alipay handled up to 2.85 million transactions per =
minute, and 54 percent of its transactions are made via mobile device.&quot=
;</span></div></div></blockquote><div><br></div><div>I know China is a very=
 big place but even so - 47,500 transactions per second would be almost qui=
ntiple what Visa handles across the entire world. With only 300 million use=
rs and primarily online usage (?) this claim feels a little suspect to me.<=
/div><div><br></div><div>Given the wording &quot;up to 2.85 million&quot; I=
 wonder if that is some freak spike caused by people&#39;s behaviour being =
synchronised externally (e.g. a fixed start time for the sale that people a=
re waiting for). It&#39;s hard to imagine that they sustained anything clos=
e to that for the entire day.</div><div><br></div><div>So this is really a =
discussion about peak performance.</div><div><br></div><blockquote class=3D=
"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left-width:1px;borde=
r-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><di=
v dir=3D"ltr">If you average every transaction around 250 bytes, then you&#=
39;d need ~15 Gigabytes per block to be broadcast and hashed by all the ful=
l nodes every 10 minutes, eating good 2Tb of storage daily... do miners hav=
e enough bandwidth and CPU power to handle this?=C2=A0<br></div></blockquot=
e><div><br></div><div>There&#39;s a discussion of such things here that mig=
ht be useful:</div><div><br></div><div><a href=3D"https://en.bitcoin.it/wik=
i/Scalability">https://en.bitcoin.it/wiki/Scalability</a><br></div><div><br=
></div><div>It discusses various optimisations, like not actually sending t=
x data twice.</div><div><br></div><div>I wouldn&#39;t worry about it too mu=
ch. It took decades for Visa to even approach 10,000 txns/sec. PayPal, I be=
lieve, still &quot;only&quot; handles a few hundred. And those services had=
 the benefits of minimal competition, working in people&#39;s local currenc=
ies, integrated dispute mediation and not representing any real threat to t=
he political status quo. Bitcoin isn&#39;t going to be needing to handle Al=
ipay&#39;s level of traffic any time soon.=C2=A0</div><div><br></div><div>F=
rankly, scaling is a nice problem to have, it means you&#39;re popular. It&=
#39;d be a mistake to just blindly assume Bitcoin will take over the world.=
 Growing market share is difficult. Worry more about how to get 300 million=
 crazy users than the precise broadcast protocol that&#39;d be needed to ha=
ndle them ;)</div></div></div></div>

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