Date: Wed, 01 Jul 2020 00:53:46 +0000
To: Hilda <hildawithin@163.com>,
 Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
Reply-To: ZmnSCPxj <ZmnSCPxj@protonmail.com>
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Subject: Re: [bitcoin-dev] Is Bitcoin mempool synchronized?
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Good morning Hilda,

> Hi there,
>
> I have been assuming Bitcoin system to be well synchronized, including me=
mpools. But after being challenged, I started to think that I actually cann=
ot verify this without knocking the door of every miner in every single sec=
ond (just a time slice reasonable to me; stop torturing me by asking why). =
Can anyone share any thoughts with me?


No, definitely not.

There is no good way to limit the amount of transactions someone can push a=
t you, except by various heuristics.
Yet those very same heuristics mean that someone with a good knowledge of t=
hose heuristics can make your mempool desynchronized with that of somebody =
else.

Fortunately for Bitcoin, it is the blockchain itself that we synchronize on=
.
People cannot push blocks at you without doing the work of grinding towards=
 the difficulty target, thus it is not possible to spam blocks.

TANSTAAGM - There Ain't No Such Thing As A Global Mempool

For this reason, any consensus rule has to refer only to data inside blocks=
, and never to data in mempools, are mempools are ephemeral and not synchro=
nized across all nodes.

Regards,
ZmnSCPxj