user132898: maybe a naive q, but I read in a book that for small value items you don't really need to wait for confirmation of a BTC transaction (i.e. dont need to wait for it to be added to a block):
I understand the rationale, i.e. waiting for confirmation is long ~10mins or so, probably not worth it for small value tx's. But now, if I didn't wait for confirmation doesn't that leave me pretty exposed to potential double spends?
Eg I am buying a coffee which is 0.01 BTC, i can pay the merchant and at the same time create another transaction paying myself 0.01 BTC. They both end up in the mempool waiting to be collected and mined. 50% of the time i'd not have paid the merchant and 50% of the time i'd have paid him...
is the only way around this to actually wait for confirmation (or even a few confirmations)?

user13866: There are several ways around this

Wait for more confirmations. Obviously this has a time penalty that is difficult for many coffeeshop scenarios.
Use something like lightning network instead.


132898: <p>maybe a naive q, but I read in a book that for small value items you don't really need to wait for confirmation of a BTC transaction (i.e. dont need to wait for it to be added to a block):</p>
<p>I understand the rationale, i.e. waiting for confirmation is long ~10mins or so, probably not worth it for small value tx's. But now, if I didn't wait for confirmation doesn't that leave me pretty exposed to potential double spends?</p>
<p>Eg I am buying a coffee which is 0.01 BTC, i can pay the merchant and at the same time create another transaction paying myself 0.01 BTC. They both end up in the mempool waiting to be collected and mined. 50% of the time i'd not have paid the merchant and 50% of the time i'd have paid him...</p>
<p>is the only way around this to actually wait for confirmation (or even a few confirmations)?</p>
 13866: <p>There are several ways around this</p>
<ul>
<li>Wait for more confirmations. Obviously this has a time penalty that is difficult for many coffeeshop scenarios.</li>
<li>Use something like lightning network instead.</li>
</ul>
