Hello

I have a question about replacing transaction with smaller fee by the same transaction (same inputs) with bigger fee. As far as I understand it should not be possible because if miner has in its pool transaction which spends an input it will not accepts any other transaction which uses the same input. However everybody says that miner choose always by fee/kb ratio, so maybe from miner point of view pool content is not important and it accepts all new transaction as long as they are OK with previous blocks. Additionally in every manual for 'my transaction with small fee stacks' everybody says that you need to wait until transaction disappear from miners mempool. But my question is when it can happen since most of miners do not restart they machines at all. So is there any timeout for transaction?