RBF vs CPFP

[Charles-Tim]

Some people might thought child-pay-for-parent is the same as replace-by-fee, thinking child-pay-for-parent was just a way you can pump bitcoin transaction fee just like replace-by-fee, although seem like that, but I think differentiating between this two terms is very important for people to know the differences and when to use one instead of the other. There could be stuck transaction, and the sender unable to pump it using replace-by-feeas the the transaction does not support replace-by-fee, what then comes to the mind of few is to use child-pay-for-parent to unstuck the transaction, but because the sender or the receiver was still using low fee in another (child) transaction, the transaction could still remain stuck, it would be one transaction (parent transaction) before and it became two transactions (parent and child transaction) that will be stuck, the other transaction is the child one. This is one of the challenges many people making use of bitcoin is facing when they do not actually knowing the differences between RBF and CPFP.

What is RBF and how to use it
Replace-by-fee is a way to pump a transaction using higher fee. In this way, the bitcoin will be double-spent, which means another transaction hash (txid) will be created, double spending the bitcoin into the same previous receivers address or into another address entirely. That is why transactions that support replace-by-fee can be used to pump the fee or cancel a the transaction. A cancelled transaction is not different at all from RBF because the transaction is not actually cancelled but double-spent into another address on the sender's wallet, the sender's wallet do this automatically if you cancel a transaction.

In a wallet that supports RBF, it is good to check if the wallet RBF is enabled or not, but like on electrum, the RBF is enabled by default, but very good to still confirm this on your wallet to make sure it support RBF. Each time you want to make a transaction, there will be an option to flag a transaction to make it support RBF, but the latest electrum starting from version 4.1.1 and up, the transaction will be automatically support RBF unless you flag it not to support RBF. Depending on the wallet you are using, but checking if the wallet itself support replace-by-fee, many or most bitcoin wallets are not yet supporting it which is one of the bad side of such wallets.

Unstucking transactions using RBF
If a transaction support replace-by-fee, you can easily unstuck it by pumping the fee, which means the fee to an unconfirmed transaction can be increased by making use of RBF, so that the transaction can have higher chances to be included in a block mined. This is the way to cancel a transaction too, the fee will be pump but the address will be changed to another address on the wallet so that the unconfirmed bitcoin transaction will be diverted from the former receiver's address to another address which is from the sender's wallet address, which means the transaction is cancelled but require higher fee. In all cases of RBF, there will be change of transaction hash (txid) as the unconfirmed Bitcoin is double-spent.

What is CPFP and how to use it
Child-pay-for-parent is a means bitcoin transaction (parent transaction) can have high chance to be confirmed by miners as a result of unspent transaction output (UTXO) in the changed address which is used along in another transaction (child transaction), but this is done when it is the sender that want to make use of CPFP. The receiver can also make use of CPFP, if the receiver is using a wallet that can spend uncomfirmed input, all what the receiver will do is to create another bitcoin transaction spending from the unconfirmed input transaction, and use a high fee.

Unstucking transaction using CPFP
Uisng CPFP can be a potential means to unstuck a bitcoin transaction but it will demand for more fee, the more fee that will be demanded for will be required for the child transaction and also an addition fee for the unconfirmed parent transaction, although the fee will be added only in the child transaction but in a way it will compensate for the parent transaction and yet enough to get child transaction confirmed. This will make miner to be able to include the transaction in a block as early as it should, and the parent transaction will be confirmed along with the child transaction as both will be included in the same block mined. So, using CPFP, you will create another transaction, resulting into two (child and parent) transactions which will require more fee to be paid, or resulting to another transaction to be created from an unconfirmed output from the receiver's wallet which will demand for fee.

When to, and when not to use RBF and CPFP
When trying unstucking a transaction, RBF must first come in mind, as it has chances of lower fee if compared with CPFP. So, before using CPFP, certain reasons to and not to use it must be known, that is why I will not suggest CPFP not to be used for unstucking certain transactions. If the original transaction hash (txid) is necessary in a transaction in certain payment, and you want to unstuck the transaction, you can not use RBF as the txid will be changed as the coin is double spent, but higher fee will be required for CPFP as explained above to create another transaction with high fee so the parent transaction can have high chance to get confirmed in a block mined. .

Also, if you have an unstuck transaction, and you want to create another transaction to be used to send bitcoin to another person that you know you will include the parent or part of the parent unspent UTXO, you can consider to use CPFP if you know that even if RBF is used, you will still have to send bitcoin to another person. In this case, you can use a stone to kill two birds by making use of CPFP because all you want at the time is two transactions. In this way, it can not be said that CPFP comes with high fee, because if you do not use CPFP,  you will still have to create another transaction to send the bitcoin to another person you want to send bitcoin to.

The reason CPFP is said to require higher fee than RBF is because during unstucking such transaction, the sender or receiver are sending bitcoin back into another address on their same wallet which require higher fee.

Check transaction input and output before using CPFP
This is more to the receiver than the sender because the sender will still know the transaction he/she created before making child transaction, but the receiver may not know this. The unconfirmed transaction can be tracked on blockchain explorer, if the transaction consist of many inputs and outputs, most especially inputs which are the ones that are more weight to transactions, it will be better not to think if unstucking such transaction, as the more inputs and outputs in the parent transaction, the more fee that will be required for the child transaction. So people will make use of CPFP and yet use a fee that can not get the parent and child transaction confirmed in time but yet stay in mempool for weeks until the mempool become less congested in a way it can get such high inputs and outputs but low fee transaction confirmed.

Using wallet that support RBF and CPFP
One thing is that a transaction that support RBF can still support CPFP, it depends on the wallet you are using. As a sender, I can say all noncustododial wallet support CPFP at the senders side, but as for receiver to make use of it, not all wallets support CPFP, also there could be a possibility of the sender wallet not to make use of CPFP, which means it is better to get a wallet that support coin control to be able to be certain that as a sender, you are sending from the parent transaction change address UTXO. Using a wallet that support spending of unconfirmed transactions is necessary if you are the receiver, a good wallet that support all this is electrum. Also not all wallet that support RBF but electrum wallet also support it. So, let me use electrum as the standard wallet and use it as an example. If you enable a transaction to supoort RBF, it is also still supoorting CPFP on electrum so far you have changed address UTXO as a sender and spending from it with higher fee that can get two transactions confirmed, or if you are the receiver, you can spend from the unconfirmed transaction with a high fee that can get two transactions confirmed. That is the reason all transactions should be enabled to support RBF, so it is still your choice to still determine which one that best suit you at the time you want to unstuck the transaction based on what I have explained above, although there are few cases of the receiver telling sender not to enable RBF.

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[SquirrelJulietGarden]

All about "stuck" transactions and what you can do to fix them (RBF and CPFP transactions)
Make sure to avoid wasting BTC for too high fees – step by step guide (Electrum). A guide to use RBF.
[TUTORIAL]getting a low-fee transaction unstuck by creating a CPFP with electrum
How to cancel Bitcoin transaction? (RBF and CPFP transactions)

Remember to mark your transaction as an opt-in RBF. It will help you have easier choice because RBF is easier to use than CPFP. In Electrum, RBF is chosen by default settings but make sure to double check the settings. If it is not chosen (by your misclick), choose it again.

When you broadcast your transaction, make double check too: Replace by Fee (on the right) will be True (should be) or False. If you see it as False, change the settings, check it again to make sure it is True.

It is not correct if you write that only Electrum wallet supports RBF or CPFP.

[ranochigo]

-snip-
 Each time you want to make a transaction, there will be an option to flag a transaction to make it support RBF, but the latest electrum starting from version 4.1.1 and up, the transaction will be automatically support RBF unless you flag it not to support RBF.
-snip-

It has been turned on by default for quite some time, since one of the version from 2018.

This is the way to cancel a transaction too, the fee will be pump but the address will be changed to another address on the wallet so that the unconfirmed bitcoin transaction will be diverted from the former receiver's address to another address which is from the sender's wallet address, which means the transaction is cancelled but require higher fee.

Almost there. Even if you were to use RBF and spend the inputs to another address, miners can still choose to include your first transaction instead of the one with the increased fee. They are both valid until one of them gets confirmed.

In all cases of RBF, there will be change of transaction hash (txid) as the unconfirmed Bitcoin is double-spent.

It is changed due to either some change in the inputs/output or some change in the value of the outputs.

No offence, the post is actually extremely wordy and some better structuring would be needed.

[Charles-Tim]

It has been turned on by default for quite some time, since one of the version from 2018.

Electrum has supported RBF some years ago, but if RBF is enabled, you will need to still flag the transaction to support RBF, unlike now which is dafault while sending unless you flagged the transaction not to support RBF.

No offence, the post is actually extremely wordy and some better structuring would be needed.

I tried my best to reduce the post contents, but will result to missing of important information for newbies. Just trying to simplify it as it could be.

[AB de Royse777]

No offence, the post is actually extremely wordy and some better structuring would be needed.

I tried my best to reduce the post contents, but will result to missing of important information for newbies. Just trying to simplify it as it could be.

Well it still wordy for me. I read the first few paragraphs with full attention and then just scanned the rest of the paragraphs and trusting that you will not put anything wrong. It will be better if you can simplify it more. I do not think at the current format and wording many people will be interested to finish the entire article.

Maybe some graphical presentation like those infography will also help.

[ranochigo]

Electrum has supported RBF some years ago, but if RBF is enabled, you will need to still flag the transaction to support RBF, unlike now which is dafault while sending unless you flagged the transaction not to support RBF.

It has been enabled by default for years and transactions are sent with the RBF flag. I don't think there were any changes to this behavior recently, 4.x.x but it was changed in 3.3.0, from the changelog.

I tried my best to reduce the post contents, but will result to missing of important information for newbies. Just trying to simplify it as it could be.

Newbies don't have to know the technical stuff behind RBF or CPFP, or anything to that extent. They just need to know how to remedy something like this, which the links in the first reply has covered together with pictorial illustrations.

[sheenshane]

AFAIK, Electrum and Blockstream Green Bitcoin wallet support both coin control, RBF and CPFP.

Newbies don't have to know the technical stuff behind RBF or CPFP, or anything to that extent. They just need to know how to remedy something like this, which the links in the first reply has covered together with pictorial illustrations.

I tend to agree when there is a stuck transaction from a newbie and we suggest this RBF and CPFP might don't know the proper procedure.  However, there's an alternative when there's a stuck transaction, you can also use accelerator service and I highly suggest using ViaBTC as the best service to accelerate your stuck Bitcoin transaction.

Anyway, for those who didn't know how to use RBF and CPFP, this thread is very helpful.  BTW, can you also include the relevance between RBF and CPFP?

[Charles-Tim]

<...>

Thanks for the corrections, as the article is right now, adding infographics to it will still require more explanations like choosing a specific wallet like electrum, explaining how to enable RBF will increase the word contents along, but I have this more in mind already in case of next time. I have tried to reduce the contents, especially I deleted the ending parts.

BTW, can you also include the relevance between RBF and CPFP?

Do you mean the importance of both? It is included in the article, but not just as subtopic, but one of the main reason I created the thread.

[tranthidung]

No offence, the post is actually extremely wordy and some better structuring would be needed.

Well it still wordy for me. I read the first few paragraphs with full attention and then just scanned the rest of the paragraphs and trusting that you will not put anything wrong. It will be better if you can simplify it more. I do not think at the current format and wording many people will be interested to finish the entire article.

It is my dear opinion for your style with which you try to sketch your sentence as long as possible. It is unnecessary. If it is only me talk about it, it likely is my biased or distorted opinion but if a few people discussed it with dear intention to help you, it can be a correction for your style.

Take or skip it, it is your decision.

I discussed it with you long time ago and it seems you ignored it and kept trying to sketch your sentence.

I tried my best to reduce the post contents, but will result to missing of important information for newbies. Just trying to simplify it as it could be.

With same content, the shorter the better. Because the more succinct your sentence is, the more probability that readers will read it all.

In short, there are at least two big problems with your posting style

• Sentence is too long. You can make it shorter, always. You think you can not make it shorter, it is not true.
• Punctuation, conjunction words
• Writing is different than speaking but they have a common thing: no one want to read or hear if your write too much (unnecessary) or talk-ative. In the other words, such style results in side-effects.

Hope you read what I posted above, I think it is clear how I mentioned 'it depends'.

Your post is very long and I don't read it all. Another minus point in your post is bad punctuations. Frankly said, it is my contribution for your writing. It is not my attack.

I bet that anyone can understand your sentence

Admin recommends the same thing.

When trying to write quality posts, a lot of people act as though they're writing a book report for school: putting facts that we already know into their own words. Nobody wants to read that, and you will not get merit for it. Moreover, the length of your post and the quality of your English are only minor factors. In trying to write a quality post worthy of merit, you should offer new ideas, personal experiences, or perspectives that other forum users will actually find new and interesting.

[Quickseller]

Using wallet that support RBF and CPFP
One thing is that a transaction that support RBF can still support CPFP, it depends on the wallet you are using. As a sender, I can say all noncustododial wallet support CPFP at the senders side, but as for receiver to make use of it, not all wallets support CPFP, also there could be a possibility of the sender wallet not to make use of CPFP, which means it is better to get a wallet that support coin control to be able to be certain that as a sender, you are sending from the parent transaction change address UTXO. Using a wallet that support spending of unconfirmed transactions is necessary if you are the receiver, a good wallet that support all this is electrum. Also not all wallet that support RBF but electrum wallet also support it. So, let me use electrum as the standard wallet and use it as an example. If you enable a transaction to supoort RBF, it is also still supoorting CPFP on electrum so far you have changed address UTXO as a sender and spending from it with higher fee that can get two transactions confirmed, or if you are the receiver, you can spend from the unconfirmed transaction with a high fee that can get two transactions confirmed. That is the reason all transactions should be enabled to support RBF, so it is still your choice to still determine which one that best suit you at the time you want to unstuck the transaction based on what I have explained above, although there are few cases of the receiver telling sender not to enable RBF.

One thing that I would note about RBF is that whoever is receiving the transaction from you is going to trust the transaction less, and will require more confirmations before considering the payment they received as "paid". For example, a business that normally accepts transactions after 1 confirmation might want 2 confirmations before accepting the payment. If a RBF is included in a block that gets orphaned, the sender could potentailly double spend the transaction if it is not included in the block that is not orphaned.

[Charles-Tim]

Newbies don't have to know the technical stuff behind RBF or CPFP, or anything to that extent. They just need to know how to remedy something like this, which the links in the first reply has covered together with pictorial illustrations.

The first link you are talking about does not contain any pictorial illustration, no image included. Also, the link only covers one aspect of CPFP (while spending unconfirmed transaction), no illustration about how sender can also make use of CPFP. But, it is a very nice article.

• Sentence is too long. You can make it shorter, always. You think you can not make it shorter, it is not true.
• Punctuation, conjunction words
• Writing is different than speaking but they have a common thing: no one want to read or hear if your write too much (unnecessary) or talk-ative. In the other words, such style results in side-effects.

This is highly unnecessary. You do not need to rush while reading for you to understand someone, that article is coherently structured. Also, no need to repeat what has been posted by previous posters which I have tried and corrected. If you still insist, is the first link suggested by ranochigo short for you, or among which you will criticize along.

[ranochigo]

The first link you are talking about does not contain pictorial illustration, no image included. Also, the link only covers one aspect of CPFP which is when spending unconfirmed transaction, no illustration about how sender can also make use of CPFP. But, it is a very nice article.

Links in the first reply.

This is highly unnecessary. You do not need to rush while reading for you to understand someone, that article is coherently structured. Also, no need to repeat what has been posted by previous posters which I have tried and corrected. If you insist, is the first link suggested by ranochigo short for you, or among which you will criticize along.

Its up to you whether you want to change the structure or not. I found it far too wordy to be in the beginners and help section as well. There are 4 links in the first reply to this thread.

[tranthidung]

This is highly unnecessary. You do not need to rush while reading for you to understand someone, that article is coherently structured. Also, no need to repeat what has been posted by previous posters which I have tried and corrected. If you still insist, is the first link suggested by ranochigo short for you, or among which you will criticize along.

If you can not see difference between your topic, your sentences and achow101's, it is you failure.

There could be stuck transaction, and the sender unable to pump it using replace-by-feeas the the transaction does not support replace-by-fee, what then comes to the mind of few is to use child-pay-for-parent to unstuck the transaction, but because the sender or the receiver was still using low fee in another (child) transaction, the transaction could still remain stuck, it would be one transaction (parent transaction) before and it became two transactions (parent and child transaction) that will be stuck, the other transaction is the child one.

Do you think this sentence is good? I don't mention about the content of that sentence. If a sentence is too long, breaks it into a few sentences. Readers don't want to read such sentence, and do you see it is failure of writing?

If readers are patient enough to read, they will be challenged (by you and your sentence) to understand the meaning. It is another failure of writing.

You write many sentences like that. Another one.

If the original transaction hash (txid) is necessary in a transaction in certain payment, and you want to unstuck the transaction, you can not use RBF as the txid will be changed as the coin is double spent, but higher fee will be required for CPFP as explained above to create another transaction with high fee so the parent transaction can have high chance to get confirmed in a block mined

It is up to you.

This post is the last time I talked about this. I get nothing when I give you my advice. No offence, no attack. Again, as I said, if it is only me, you can say I am attacking you personally but look who gave you advice?

Naturally, people think they are doing the best, before the times they do something better and when they look their past works, they will realize something.

My advice is what I learned, from my teachers, lecturers, and textbooks about Writing. If you have yet read any textbook for Writing skills, let's try to read one such book.

• 10 Amazing Books That Will Improve Your Writing Skills
• I did not read any of those books (simply searched and found them) but I shared because good books for Writing do mention what I told you.
• Did you know the saying "If you can't explain it simply, you don't understand it well enough"?