There are a variety of different ways that an unconfirmed transaction can end up not being confirmed at all.
It can be double spent, most commonly via a race attack where the sender of the transaction spends the same inputs in a second transaction with a higher fee, and that second transaction is mined first, rendering the first transaction invalid. If replace-by-fee is enabled, then it is very easy to replace a transaction and essentially "cancel" it. Transactions can end up in stale blocks, either through a malicious attack or just because two blocks were mined in rapid succession, even after they have received a confirmation. Transactions can time out and be dropped from the mempool entirely, although in this case there is nothing stopping the receiving party from rebroadcasting it.
Have a read of this page for more info: https://en.bitcoin.it/wiki/Irreversible_Transactions#Attack_vectors
Topic: Why people afraid so much about the confirmation's duration? - page 2. (Read 716 times)
When someone sends X BTC to an address the transaction becomes unconfirmed and gets spread over the world. No one can stop that.
I've just seen many people here discussing that bitcoin is not instant payment for shops. Since no one can stop the transaction and the satoshi per byte has a limit on how low you can set it, why people afraid that miners won't mine their transactions? Memory pool keeps them for 2 whole weeks.
I've just seen many people here discussing that bitcoin is not instant payment for shops. Since no one can stop the transaction and the satoshi per byte has a limit on how low you can set it, why people afraid that miners won't mine their transactions? Memory pool keeps them for 2 whole weeks.
Jump to: