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Questions tagged [transaction-selection]

Questions about what criteria influence the selection of unconfirmed transactions for block inclusion.

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how does a miner choose which transactions go into the next block?

how does a miner choose which transactions go into the next block? do all transactions go through or is there a lottery process? I understand transactions with higher fees are given priority.
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334 views

Who decides who verifies Alice's transaction?

Let's say the transaction got picked up into a block by miner A and into a block by miner B. Both are working on those separate blocks, and each block contains information about Alice's transaction ...
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392 views

Can a Bitcoin miner process their own transactions for free?

Can I become a Bitcoin miner by setting up multiple nodes to give higher priority to my own transactions to process them for less fee or for no fee? My understanding is that a confirmation is when a ...
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Does Stratum cause mining to be more centralized than getBlockTemplate would?

I read the question "I don't understand the "51% attack" problem. Why does a mining pool have power with a 51% share?" and its anwers. That made me wonder that since the GBT protocol is ...
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443 views

Why does only the earliest transaction matter for double spending?

On page 2 of Bitcoin paper, it says: The problem of course is the payee can't verify that one of the owners did not double-spend the coin. A common solution is to introduce a trusted central ...
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3answers
539 views

Why are there always some unconfirmed transactions?

As far as I know, a miner begins creating a new block as soon as it receives a valid block from another miner. It then begins to construct and hash the next block on top of the block it just received ...
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57 views

What, other that Fees and Luck, controls the time to confirmation?

Are there any factors that contribute to how fast a transaction is confirmed other than the Fee (sat/B), and a little bit of luck? Does it matter what service is used? How large the transaction is? ...
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Once SegWit is implemented, could updated miners still choose to ignore SegWit transactions?

Regular transactions can be ignored. What about SegWit transactions?
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224 views

Why is the network congested?

I'm reading a lot of people saying that is taking around 3/4 days to confirm a transaction. What are the reasons for this being happening?
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Transactions are not guaranted to be validated

I have read some posts about transactions never to be confirmed, but those post implied small transfers with no fees. In my case my two transactions have something like 0.000428 BTC of fee. I don't ...
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392 views

How does a miner know if a transaction has already been included in the block chain? Does he traverse through the complete chain to conclude this?

I am confused on what incentive a miner has on including a transaction apart from the transaction fee. So, if adding a transaction wastes any time, any miner should ideally not add transactions that ...
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How often are mining nodes updated with new transactions [duplicate]

Apologies if this has been asked, I'm a bitcoin noob. I'm having a hard time understanding how bitcoin scales. If bitcoin scales massively, to millions or billions of transactions per day, how will ...
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192 views

Is it OK not to sort transactions at all?

According to Mastering Bitcoin. Mining - Transaction Age, Fees, and Priority, miners sort transactions, using special parameter, called priority, which looks like Priority = Sum (Value of input * ...
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Is the probability of generating invalid blocks reduced by mining transactions unknown to others?

I've got a question concerning a possible mining strategy. I've not found any proof of the strategy, but it seems reasonable to me. If two mined blocks inserted in the block chain include the same ...
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2k views

As of 2017 is it still possible to get a transaction confirmed without a fee?

In the past it was possible to get a transaction without a fee confirmed if the inputs and outputs had a high enough priority and followed some rules. As of 2017 is a "free" transaction still possible ...
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221 views

What happens between submitting a transaction to the network and it being confirmed?

I am very new to bitcoin, appreciate any help that I can get for below queries. 1) Is there any way (site or app) to know, to which node my current (latest) transaction is headed to? Does it go to ...
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Why does Antpool mine so many empty blocks?

AntPool, the largest mining pool mines a lot of empty blocks (quick stat over the last 100 blocks they mined at time of writing shows 20% <10kB). While I understand that sometimes it is useful to ...
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2answers
377 views

Are any miners still considering priority in their transaction selection?

A new answer on Who gets Bitcoin transaction fees? has spawned discussion on the paradigm shift from selection by priority (= coin age × spent value) to selection by fee rate `(= fee / transaction ...
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Minimum number of transcation in blocks one must include? [duplicate]

Anybody as the miner can just include 1 transaction and mine 12.5 award transaction and nonce and although it may not speed up my process as (number of transaction +Award+ Nonce)=some Constant to be ...
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220 views

Restarting mining on new transaction

I understood that when a new transaction comes in, the miners have to start over, or at least change their merkle-tree to include the new transaction, essentially starting from scratch again. If I ...
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1answer
356 views

How is the mempool incorporated in the calculation of the block hash?

So I've been reading about how the nonce is calculated. There is one part that I don't get. So there is a mempool, and each node (or mining node) takes a part (or the whole part) of that mempool, ...
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2answers
799 views

Creating empty blocks vs creating full blocks

I've already read many different answers to this topic. Is it correct that the miner decides on his own if he includes any transactions in his block and how many (as long as the block size is <...
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2answers
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When we can agree on mempool sorting order, we can just confirm first n-transactions that are at least 10 mins old. What's missing?

When we can agree on a mempool sorting order, we can just confirm first n-transactions (or 80% of transactions) that are at least 10 minutes old. Then, we can transfer (broadcast) the block header ...
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What is the largest number of blocks a transaction has ever waited for confirmation?

What is the largest number of blocks a transaction has ever waited before eventual confirmation? Please exclude: Transactions with no fee Transactions delayed because of unconfirmed inputs ...
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431 views

How does getblocktemplate select transactions?

I wrote a script that compares the transactions listed in the memory pool with the transactions included in getblocktemplate: http://learnmeabitcoin.com/explorer/node/memorypool (I've ordered the ...
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2answers
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How are transactions collected into new block?

How are the latest transactions collected into new block to send them to miners for hashing? Which part of the network is responsible for giving miners the correct block to hash?
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Is there a way to create a transaction that it can only be confirmed after another unrelated transaction has been confirmed?

Is there a way to create a transaction A that cannot be confirmed until B has been included in a block, although A does not build on any UTXO B creates? B would have already been broadcast by another ...
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Are sequential blocks more likely to be “empty” if solved by the same entity?

If not SPV mining, so-called "empty blocks" occur if there are no available transactions to include and is usually when the previous block was solved a short period of time previously. Is there any ...
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2answers
379 views

How often do miners recalculate the merkle root they're working on?

I think that I understood most of the things about Bitcoin but there is still a mystery. We can see on https://blockchain.info/ that there are up to 4/5 new transactions every seconds. My question ...
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1answer
354 views

How does Bitcoin Core sort memory pool transactions by fee?

I'm trying to understand the algorithm Bitcoin Core uses to sort memory pool transactions by fee. Gavin's fee rework proposal states: Next, sort all remaining memory pool transactions by fee-paid-...
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1answer
2k views

How can a miner choose which transaction to include in the next block?

This question is not a duplicate of Can miners choose which transactions to mine? Everybody seems to agree on the fact that miners can select which transactions they are mining. But I can't find a ...
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2answers
347 views

Will a new block be found immediately, when there are enough transactions to fill a block?

I am trying understand the Bitcoin verification process. What happens, if a new block has not been found and there are enough transactions waiting to fill the current block size limit? Will a new ...
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1answer
249 views

Why is utxo time a priority for miners?

I've understood (maybe mistakenly) that once free transactions arrived to be collected into new block the miner will prioritize them by fee, then by maturity, meaning will take the transaction with ...
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297 views

Transaction inclusion into block

What are reliable and good sources for understanding the procedure of transaction inclusion into a block? Problem outline: Given, there are multiple peers - let's say 5 - in a test network, where 3 ...
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326 views

What is the motive of a miner to include transaction in a block?

My question is divided into different parts : Can a block include only coinbase transaction ? Why should a miner wait \ include more transaction after starting to create a block ? If a miner stops ...
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1answer
239 views

Are transactions in a block decided by mining pool operator?

My assumptions: Most pools have an operator. All individual miners part of the pool work on block with address of the coinbase transaction owned by pool operator. pool operator gets all the bitcoins ...
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1answer
398 views

What is criteria of mining priority except for transaction-fee?

I am reading "Mastering Bitcoin written by Andreas" and I found this explanation of mining. Transactions are added to the new block, prioritized by the highest-fee transactions first and a few ...
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2answers
506 views

How are unconfirmed transactions divided into different blocks?

According to https://bitcointalk.org/index.php?topic=216938.0 one transaction can only be contained in one block. If I understand correctly, miners can freely decide what transaction they include in ...
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168 views

What transactions will be included in the next block?

The miners decide whether a transaction will be included in the block. What information do miners have about unconfirmed transactions? How can I know, in detail, what transactions are going to be ...
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1answer
593 views

Can miners choose which transactions to mine?

I'm curious if miners can choose which transactions to mine? I know that there are limits to the minimum size of a transaction fee (around 5400 satoshis) but I'm wondering if miners can ignore those ...
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1answer
215 views

Transactions used to form a block

I've read the Developers Guide ( bitcoin.org/en/developer-guide ), asked a few peers and I still don't understand how the transactions are used to form the block. I did get that the transactions are ...
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1answer
283 views

What if some group of people start sending small transactions from wallet to wallet just to make the blockchain bigger?

What if some government start using their computers to move the tiniest amount of Bitcoin possible, from wallet to wallet, just to make the blockchain REALLY big? Is this possible? And also, is it ...
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1answer
921 views

How often do miners update their block transaction list?

Assuming an interval where no block is found, do we know how often the typical miner updates his block transaction list with new transactions from the mempool? I found a reference which suggests that ...
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1answer
2k views

Bitcoin transaction priority calculation

From the Bitcoin wiki page on transaction fees: Transaction priority is calculated as a value-weighted sum of input age, divided by transaction size in bytes: priority = sum(...
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1answer
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Can zero-fee txs get into a block?

What happens if a transaction is set to have zero fees? Can it get into a block? Also, if you updated a coin's code to accept zero-fee transactions, would this cause a hardfork? (e.g. made tx's in ...
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2answers
274 views

How Is Block Assembled?

I think I understand mining well enough, but what I don't get is how the blocks of transactions are assembled. According to this post - What exactly is Mining? - the miners assemble the blocks and ...
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2answers
782 views

Does a new block necessarily include all transactions that occurred before its generation? What about network latency?

I read What exactly is Mining? and What are bitcoin miners really solving?, but was left wondering: What happens if a new transaction comes in, whilst mining? To answer that, I found Do transactions ...
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1answer
161 views

Mine valid but nonstandard transactions

Is there a way to configure cgminer to accept valid but nonstandard transactions for mining? If not, where, theoretically, would be a good place to look if I was interested in mining nonstandard ...
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2answers
661 views

How exactly does a block get constructed and verified?

From what I understand, a new block contains all the transactions within the last 10 minutes. So when Alice sends Bob 10 BTC, how does this information get put onto the newest block? I guess I am ...
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How long do miner collect transactions to include in a block? [duplicate]

I don't really understand which transactions a miner includes in a block. Since the transactions are hashed, any newly included transaction in a block should cause a restart of finding the correct ...