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Questions tagged [blocks]

This tag is for questions dealing with the structure of blocks.

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2answers
63 views

Who are the miners?

In blockchain there are some miners who calculate hash and get reward but my question is who are the miners or how can I be a miner (assume). If there are then I can be connected to a miner? I am ...
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2answers
284 views

Modify number of confirmations

By default there are 24 confirmations but I am running a testnet with just 3 miners and I would like to change this number bucause it makes not sense to have 24. I have been checking ...
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1answer
195 views

How to read previous blocks data?

I'm new to block chain technology. I'm trying to store and read blocks using testRPC along web3.js. I'm able to get the latest block data but not able to fetch previous blocks data. Please some one ...
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1answer
16 views

How do Miner choose transactions for a block?

i am wondering how a Miner chooses the transactions, he want to mine inside a block. For example, a Miner has got the Transactions T1 and T2 at the moment he starts a new mining work. This Miner is ...
0
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1answer
195 views

How to get erc20 contract deploy time / block number

I am building a framework for ERC20 tokens. Aim is to scan all events (Transfer and Approve) generated by ERC20 contract, for which I am using web3.js getPastEvents. I have set the toBlock to web3....
2
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1answer
22 views

Can the block number be set back in ganache?

I know about tools like ganache-time-traveler that let you advance the block number. But is it possible to go back to a lower value?
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1answer
14 views

In ethereum network how data structured and is every data stored, is public?

Let's say, 3 companies are using ethereum network. Company A Company B Company C Company A put some data, block01 and block02. So ethereum network looks like, Genesis Block -> block01 -> block02 ...
12
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4answers
7k views

How can I get the data of the latest 10 blocks via web3.js?

How can I get latest 10 block data by using web3.js like most block explorer does?
1
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1answer
290 views

How to get the value of the transaction?

I am using web3.py but I need help to know the value of the transaction sent. I know that the information is stored in the input but how do I parse the string. I know nothing about ABI. Here is the ...
0
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2answers
25 views

Does a transaction that consumes the block gas limit take an entire block by itself?

Does a transaction that requires the entire block gas limit to be executed (currently ~8M) take the entire block by itself? And if that's true, will that transaction take longer to get confirmed than ...
1
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3answers
175 views

Transaction receiving ether from a contract address

Are transactions sending ether from contract addresses to normal addresses listed in block.transactions or are they not trivial to detect? If not in block.transactions than how to detect?
1
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1answer
63 views

Looking for an Ethereum sniffer

I have been looking for a sniffer similar to Bitcoin P2P Network Sniffer (https://github.com/sebicas/bitcoin-sniffer) which could allow me to connect to Ethereum nodes and listen to blocks and ...
0
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1answer
25 views

Is there any library to estimate timestamp of future block?

I am in need of a library that estimates a date or some sort of timestamp when fed with a future block number (on mainnet or any major testnet). For instance, https://etherscan.io/block/countdown/...
1
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1answer
21 views

Make sure I don't jump any blocks

I'm making a simple program to track transactions in and out of an address, I have a function that gets the latest block and then I run it consecutively. When I run the function sometimes the block ...
23
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3answers
11k views

Is it possible to cancel a transaction?

Is it possible to cancel a transaction broadcast to the blockchain? Suppose I broadcast a transaction and want to cancel it before it has been mined. Is this possible? This could be useful on ...
0
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1answer
13 views

Can I rely on certain oracle to know the precise and reliable timestamp?

I am learning the security impact of smart contract on system properties like block.timestamp and block.number. I understood that block.timestamp can be controlled by the miner to certain degree and ...
1
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3answers
195 views

Increase block number on Ganache

How can we increase block.number on Ganache for testing purpose ? If not possible do you know an alternative like passing X fake transactions to artificially increase block.number. Or if we have to ...
1
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1answer
36 views

How will Proof of Stake affect blockhash generation

When (and if) Ethereum switches to proof of stake, how will the hash of blocks (most likely) be set?
1
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1answer
22 views

“The bigger the block size, the greater the computational power needed to mine a block” Does this make sense?

I was going through one of the papers and the authors in the paper mentioned this statement. I am not able to find the correlation as such. I do understand that Larger blocks may propagate slower ...
1
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1answer
27 views

Fetching block template from node

The most famous opensource pool uses eth_getBlockByNumber method with parameter "pending" to get block template and generate jobs from it. But now, in parity, I found that this parameter is deprecated ...
1
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1answer
38 views

Getting the last synced block is 0

I am trying to get last synced block but it always 0. So I have run geth --syncmode fast -cache 4096 --rpc Here is a logs INFO [12-19|09:47:50.058] Imported new state entries count=...
5
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1answer
31 views

Will block numbers be sequential on a sharded blockchain

When Ethereum shards (assuming it does) will the block numbers across the multiple shards be unique? I doubt it (I don't think the shards can have sequential block numbers and be independent of the ...
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0answers
14 views

Mining pool assign blocks

I've been researching mining pools to figure out how they assign work to miners. I understand that pool would get a job from the blockchain they only has a header, dag, difficulity, probably block ...
3
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2answers
232 views

Avoid using “now”

I am using "now" to save the block timestamp details. But there is a warning to avoid its usage. If we need to avoid it what is the best alternative to it.
1
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1answer
30 views

Are transactions to EOA included in a block guaranteed to be successful?

Regardless of the source of the transaction (externally owned address / smart contract) and the data included within the transaction, if the destination is an EOA and the transaction was included in a ...
2
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1answer
35 views

Are transactions with zero data included within a block guaranteed to be successful?

I know there are transaction receipts to verify that a transaction included in a block was executed successfully and funds were actually transferred. But can receipt verification be skipped if I'm ...
0
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1answer
10 views

How to get blocks from which an adress has taken coins&

I need to undeerstand how to find out from which blocks come coins that are currently stored at somee adress.Will be pleased to hear any suggestions.
2
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2answers
93 views

What is the difference between account nonce and block nonce?

Block and accounts both use a value called "nonce" but they seem to represent something very different. For account I understand that the nonce is an integer quantity indicating the number of ...
18
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3answers
4k views

What is the default ordering of transactions during mining, in e.g. geth?

I know that the yellow paper does not specify how transactions are to be ordered in a block and this is up to the miner to decide. But I am interested in how this is practically handled (I assume not ...
4
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1answer
48 views

Timestamp in Ethereum

I have a smart contract where the user inputs temperature readings, I'd like to add a time stamp to relate those reading with a current time of submission. I understand that in Ethereum we only have ...
0
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1answer
37 views

How to calculate average gas price of several blocks?

I want to calculate average gas price of several blocks (in Gwei), however I don't see how a field on blocks for gasPrice. Do I have to calculate it by grabbing the gasPrice of each transaction in ...
0
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0answers
17 views

Parity synced at not existing block 4839212

I have problem with parity, cant get synchronization in archive mode to end, anything, changing arguments, max-, min-, snapshot-peers, parity verisions do not help. I have blockchain in archive mode ...
0
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0answers
29 views

Is latest block returned by eth.getBlockNumber fully processed

According to web3 docs, web3.eth.getBlockNumber returns the number of the most recent block. My question is simple. Is it safe to assume block's transactions and events are already in the node or ...
0
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0answers
45 views

What is the m_seal fields in the block header used for?

Can someone please explain what these extra fields in the block header are and what are they for? Edit: Oh, I just understood myself -- mixHash and nonse are stored here. But why is this data ...
3
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1answer
232 views

When is a new block created?

I am currently reading an interesting book about solidity, and I'm reading about block creation. This gives a good overview: The book mentions that the maximum size of a block is determined by the ...
1
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1answer
19 views

Can I get the timestamp for a transaction added to mempool?

Can I get the time stamp on when a transaction was added to the mempool and when it was successfully added to a block? Is there an API to do this?
0
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2answers
37 views

Uploading big contract to the Ethereum blockchain

As far as I understand, there is a limit on the block size. But what if I want to upload a large contract that exceeds the blocksize? Will it not be allowed?
1
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1answer
48 views

Is there a smart contract recording all block hashes on in the ethereum blockchain, as they come in?

I'm wondering whether anyone has already made a contract and corresponding off-chain service which, once every 30 minutes or so, triggers the contract to record all the block hashes which have gone by ...
6
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1answer
1k views

My friend sent me a screenshot of a transaction hash, but when I search for it I find divergent data. What happened?

This is the transaction hash: 0x90e923ee01d9dfeb95ee176819eeec67d247fc6cb009c8cdc4d8ae1939e5ecc6 And this is the screenshot my friend sent me: If you check the hash in Etherscan, some informations ...
2
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1answer
33 views

Known cases of miners withholding blocks when used as randomness?

There are some applications that use the blockhash as a source of randomness, often with a payout similar to a lottery. I've heard of attacks where it would be more profitable for a miner to withhold ...
1
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1answer
488 views

How reliable is it to use Block number to calculate Time in Smart contract?

I have seen contracts use block numbers to manage when the crowdsale should start and stop. How reliable is this? I understand the average time in ethereum is 17secs between blocks, but can this be ...
3
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2answers
73 views

Reading most recent blocks without syncing chain

I would like to be able to read the newly created blocks and list of transactions it included within, without storing the chain on my desktop. Can that be done? Thanks.
1
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1answer
67 views

Get the time a block was mined

My front-end displays the timestamps of various contract actions that have taken place. However, the current block.timestamp it's using isn't very accurate, because the miner has some leeway in ...
1
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2answers
53 views

All my blocks has deleted

I have a private network for testing. My problem is when ever I stop running geth network, all of my mined blocks are gone. I run like geth --datadir "ethereum/node1" --port 30301 --networkid 1234 --...
1
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1answer
89 views

Examples of light-client interactions to extract Merkle proofs?

I'd be grateful for pointers to working examples of interacting with the geth/parity light-client protocols. I'm particularly interested in working code which shows how to extract the Merkle proof ...
0
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1answer
13 views

changing source of random number based on reward?

Would this be an acceptable way to produce a random number dependent on the reward? Say if the reward is high enough to entice a miner to manipulate the block then the contract will utilize oraclize. ...
0
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0answers
12 views

How to read the data from block?

In my smart contract, I am inserting plain text message. I can also update the message. After updating, if I want to see the previous message, is it possible? Can I see all the data in etherscan.io?...
1
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0answers
41 views

How to mine a Empty Block or reject transaction?

How Can a miner can mine a empty block,reject honest transactions to be added into block ; does it mean we could tweak the miner client , if yes could someone tell how it is done and what are the ...
1
vote
1answer
151 views

How can i implement deadlines in smartContract?

Suppose I am running a gallery and ask participants to submit there paintings before a specific date. After passing that date participant should not be able to submit their entry. How can I implement ...
2
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0answers
67 views

How to read block propagation delay from ethstats.net?

I am wondering what is the average (or mdeian) time it takes to propagate a block in the Ethereum blockchain? I found ethstats.net provides a cummlative graph for block block propagation but do not ...