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Questions tagged [block]

This tag should be used for questions related to Bitcoin blocks

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42
votes
6answers
21k views

Why is downloading blocks taking longer and longer?

First off, this really needs to get fixed. I'm downloading blocks for at least 8 hours now, and it's still not done. I know the problem of having to download the entire block chain is being worked on, ...
25
votes
1answer
14k views

When a block is “discovered” how is the nonce determined?

I know that a block is based on a random number called a nonce, but if that number is random and unknown to the miner, how is that number actually verified as the correct nonce and not some arbitrary ...
25
votes
4answers
72k views

The bitcoin mining algorithm from a programmer's viewpoint

This page: Blocks said mining is actually to solve a mathematical problem, but reading Block hashing algorithm doesn't give much help. I also tried reading bitcoind source code, but reading code takes ...
21
votes
2answers
4k views

What are the arguments for and against the increase of the block size limit?

Can someone give a quick point by point list, what arguments the proponents and opponents of increased blocksize have for their case?
20
votes
6answers
2k views

What encourages Bitcoin miners to relay blocks?

Lets say I'm mining bitcoins, and I've just received a new block that someone else has mined. What encourages me to send that block to anyone else. I can understand how the original miner wants to ...
18
votes
1answer
7k views

What is the expected time until the next block is found?

https://bitcoin.stackexchange.com/a/3908/659 says: Luckily, you'll only have to wait five minutes on average for a block to be found (blocks are one every ten minutes, so the expected delay until ...
16
votes
3answers
7k views

How to calculate new “bits” value?

Every 2016 blocks one needs to calculate new bits value. What is the formula to calculate it?
16
votes
3answers
5k views

What is the number of transactions in a block?

What determines the number of transactions that can be validated in a block?
16
votes
3answers
1k views

What are the advantages/disadvantages of a continuously decreasing block reward compared to the current method?

The current method to control the bitcoin supply to a maximum of 21 million BTC is to reduce the block reward (currently 50 BTC/block) by 50% every 210000 blocks. In this forum post there is a ...
15
votes
4answers
15k views

Why does each block store a Merkle root?

I understand how a Merkle root is calculated and stored in the block. But how do miners verify a transaction using the Merkle root? Here are 18 conditions that verify a transaction. None of them uses ...
15
votes
2answers
2k views

What's the purpose of a maximum block size?

Bitcoin has a maximum of 1 MB of transaction data in each block. Why is this limit present? When was it added? Was it intended to be temporary?
15
votes
1answer
1k views

What happens when a miner does not claim all fees/generated coins?

Suppose that a miner for some reason has the generation transaction of their blocks not take all the possible coins. This can happen for a variety of reasons, almost all of which are bugs: An off-by-...
15
votes
1answer
3k views

Bitcoin Block Size - What are the rules?

What is the maximum size a block can be? Is there a minimum size? Can you have a block with 0 transactions included?
15
votes
1answer
1k views

How can a non-miner store data in the block?

If I am not a miner and would like to put arbitrary data in the block chain, is there currently any method or protocol to get a miner to add it for me?
14
votes
2answers
5k views

How do you make a Genesis block?

What is involved in creating a genesis block? What makes it different from the other blocks in the chain.
14
votes
2answers
908 views

Does block size effect Miner's Hashing speed?

From my last question: Bitcoin Block Size - What are the rules? I learned that the block size can vary from a few kB up to a MB. This leads to my next question: Does the block size effect a miner's ...
13
votes
2answers
10k views

Why can we have small fractions of a Bitcoin?

I didn't study the inner workings of Bitcoin (yet), but already since when I just started using it, I wondered why a Bitcoin can be split up in parts. Because there is a limit on the amount of Bitcoin ...
13
votes
3answers
7k views

What is the exact formula for calculating transaction fees?

According to the Wiki: If the blocksize is more than 250 kB, transactions get increasingly more expensive as the blocksize approaches the limit of 500 kB. Sending a transaction when the blocksize ...
13
votes
1answer
9k views

How to get a bitcoin address's balance?

I know blockchain.info has an API: https://blockchain.info/q/addressbalance/134dV6U7gQ6wCFbfHUz2CMh6Dth72oGpgH gets the bitcoin address's balance,but it's not open source and must connect to the ...
12
votes
2answers
2k views

Who mined the infamous block 364422?

Block 364422 contains a transaction that takes a long time to verify. This transaction design demonstrates a way a denial of service attack could be executed. This prompted Gavin Andresen to propose ...
12
votes
1answer
3k views

Has any illegal data been saved in the Block Chain?

Has any illegal data been saved in the Block Chain, such as an illegal number, or illegal prime?
12
votes
2answers
2k views

Two blocks, two transactions, same hash

Would a block containing a transaction with an identical hash as a previous transaction be considered valid? That is, if someone made a transaction for generating Bitcoins and solve two blocks with ...
12
votes
3answers
10k views

Number of transactions per block

I am just starting to understand the internals of bitcoin. I am a CS graduate and familiar with most bitcoin terminologies. I've read Satoshi's paper and researched the question but I couldn't find ...
12
votes
2answers
729 views

Is it possible for the network to stop finding valid blocks?

The hashing problem is by design computationally hard, because SHA-256 hashes are for all intents and purposes random strings with no direct link to their inputs, and there's no (known) way to ...
11
votes
6answers
6k views

So I mined a block, but why would other nodes accept my mined block?

When a miner finds a hash and is thus able to confirm a block of transactions, that miner will then broadcast the confirmation (block?) to the other Bitcoin nodes so that it can be added to the ...
11
votes
4answers
15k views

Can there be a blockchain without mining?

This is a question about Blockchain in general, not about Bitcoin as a currency on top of Blockchain technology. Let's say I want to issue a vote on top of, lets say, multichain. I would issue an ...
11
votes
4answers
6k views

Which is the relation between transactions and blocks?

I don't quite understand the relation between a transaction and a block. I imagine it as a list of blocks, and each block having a list of transactions but I have some doubts. When I do a transaction....
11
votes
1answer
5k views

What is the magic number used in the block structure? [duplicate]

What is the Magic no used in the block structure, why is the value always 0xD9B4BEF9 and what is it used for ? Thanks
10
votes
3answers
7k views

What are the equations to convert between bits and difficulty?

If we take block hash 0000000000000006770c3806960539ca83a24facbd99ea212f37f2a0e6a5629a for example. The difficulty as a 32 bit float is 50810339.04827648. The difficulty in bits as an unsigned 32 bit ...
10
votes
1answer
11k views

Is there a limit on number of transactions included in a block? [duplicate]

As per my understanding, every transaction is included in a block and the difficulty to find a block gets adjusted such that one block is found for every 10 minutes. Is it the case that all ...
10
votes
1answer
3k views

Where is the UTXO data stored?

When a new transaction is received it is added to the memory pool (after checking for conflicts). While mining, only the transactions which are in the pool are considered. What happens to the ...
9
votes
8answers
3k views

Can more than 1 block be solved per 10 mins on average (LONG TERM)?

I am wondering whether it is possible for a supercomputer to find the next 1000 blocks in a very short amount of time. Hypothetically, if a government agency concentrated a supercomputer on hashing, ...
9
votes
2answers
7k views

How is a proof-of-stake block mined at the block level, and how does it accomplish it's goals?

I've seen many broad overviews of proof-of-stake mining, and descriptions, but I have not seen any good description of what goes into actually mining and verifying a proof-of-stake block, and how it ...
9
votes
1answer
1k views

What is the motivation for miners to include all recent transactions in a block?

I think I understand the basic operation of the Bitcoin protocol. Blocks are the "long-term memory" of the network used to prevent double spending (and the way the network agrees in first place). ...
9
votes
1answer
28k views

Whats the process of Creating a Block on the BlockChain

have been mining on pools and blindly going a long for the ride of > generating a block Can somebody walk through the process in simple terms of the steps involved in creating a block on the ...
9
votes
2answers
4k views

Locating transactions by the relayed by IP in blockchain.info

I'm working on some stats and I was wondering if the relayed by IP on Blockchain.info can be used to get an approximate (country level) origin of the transaction. Would it be reasonable to assume that ...
9
votes
1answer
818 views

Does the synced blockchain always grow in size?

Every time the Bitcoin-Qt is launched, the blockchain syncs to update to its latest state. Does this mean the data stored locally will always grow continously, eating up all available space eventually?...
8
votes
2answers
3k views

What is chainwork?

If I run the RPC call getBlock on the bitcoin-qt client it gives me field called chainwork containing a hash. I cant find any information what this value is about. Request: getblock ...
8
votes
2answers
26k views

How many Bitcoin are mined per day?

A block is generated every ten minutes. The reward changes periodically, and will halve 32 more times. What is the approximately daily reward across the entire network?
8
votes
4answers
603 views

Can Bitcoin blocks be organized into shards?

Bitcoin Scalability is a hot topic. In database architecture design data is segmented into shards or the data is partitioned such that it can be spread among large number of machines. In the ...
8
votes
3answers
14k views

How many blocks are there in blockchain as of today?

I have currently downloaded 300,000 blocks and the last one is generated 1 year and 19 weeks ago. I wonder how many blocks are more to go, before I am up to date.
8
votes
2answers
388 views

Why is the Block Header txn_count field always zero?

According to the Protocol Specification, the txn_count field of a Block Header is always set to 0, why is that? What are the intended future uses of this field?
8
votes
1answer
1k views

How does merged mining work on a technical level?

In bitcoin, miners hash the header twice with the SHA256 function. This header consists of the fields listed below, as described by this question. version previousHashBlock merkleRoot time ...
8
votes
1answer
992 views

How do blocks signal whether it supports segwit for the 95% threshold?

Ideally, I'd also like to see graphs that indicate how close we are to segwit adoption and the number of minimum blocks we are away from actual segwit adoption.
7
votes
1answer
31k views

How many transactions in One Block? [duplicate]

Block is collection of transactions.Who can decide Number of transactions per block? and How transactions are selected in block? and How does the priority works for fee transactions? Thanks
7
votes
3answers
3k views

How can I recover from a corrupted blkindex.dat on Ubuntu 12.10?

I've installed Bitcoin-Qt after a clean WUBI install, and installed Bitcoin-Qt directly. Now it suddenly says "Error loading blkindex.dat". I assume my blkindex.dat file is corrupted, and I tried ...
7
votes
4answers
501 views

How is it possible that transactions can be added to a block currently being mined?

It seems counter-intuitive that the current block can be hashed and transactions can be added to it, however that is what this thread indicates. Can someone help me connect the dots (not necessarily ...
7
votes
2answers
1k views

What would happen if two blocks had the same hash?

Consider the following scenario: January 2016 block A gets submitted. Its hash is 0001010. January 2017 block B gets submitted. Its hash is also 0001010 (collision). 10 minutes later, block C gets ...
7
votes
2answers
2k views

When does a miner decide to stop collecting transactions and start calculating hashes to try to win?

I am confused about whether a miner chooses to wait for more transactions (more fees) or starts as soon as it receives the first transaction from the network. Once a miner has started calculating the ...
7
votes
2answers
2k views

How to prevent a miner from stealing another miner's block?

Many articles only contain a phrasing like A miner A solves the hash problem and gives the result to the network to check. Once a majority of the network confirms, A gets the reward. But how does ...