Isn't there something called the replace by fee patch which miners can accept the transaction with more fee than the transaction with less fee? Most mining pool didn't implement that. IIRC, most miners only accept the transaction which reaches their node first and most nodes only relay transactions with inputs that aren't already in your mempool. The 1 block fee can be quite high if the network load is high. If an attacker stresses the network with high fees, your transactions will get pushed down to the bottom unless you are willing to pay a premium.
IRC, RBF could be done either as a kind of double spend (term was actually countermeasure), or a type of multisig. In the countermeasure you broadcast a TX with higher fees to "replace" the one with lower fees. There is some magic that has to happen on the input output balancing to make it fraud resistant.
The multisig RBF case is where you allow people to add inputs to the transaction to cover fees. Requires a special sig bit.
CPFP seems to be implemented on Eligius pool, so if you attempt a CPFP then you have a fair chance that Eligius will pick it up whenever the win a block.
That is exactlly what happened with this transaction. Eventually Eligius picked it up.
https://blockchain.info/tx/4cc3e2b6407ae8cdc1fd62cb3235f9c92654277684da8970db19a0169e44c68c
https://www.blocktrail.com/BTC/tx/c6e75325c6de22f7bacd2e1369e4067bfbde87fec4af8ca13b407de21a985ecf
my trx still unconfirmed trasaction in 60 hours ,
my trx still unconfirmed trasaction in 60 hours ,
Still got you beat... going on 4 days
[89 hrs] Who has the mempool unconfirmed TX highscore? [week of Jul 5th]
I'm tempted to sweep it, but don't want to loose my high score
