Questions tagged [blockchain]

The Ethereum blockchain is a distributed database based on the Ethereum whitepaper specification and stores both the full transaction list and the most recent state.

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1answer
6k views

Optimal sync mode for running an ethereum node that can process transactions

I need to run a local ethereum node, I've downloaded mist wallet but I've had some issues. I have to redownload the whole blockchain again, and I noticed that the problems I had could be related to ...
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1answer
316 views

Why does geth -light start importing block headers from 3297471

I've been using geth to download the blockchain (on full) and one of the requirements for my research involves the use of light clients. I used 2 computers to download the blockchain on the -light ...
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1answer
185 views

Smart Contract different behaviour on testnet vs Solidity Browser

The following smart contract behaves differently on Solidity Browser and testnet: pragma solidity 0.4.2; contract mortal { address owner; function mortal() { owner = msg.sender; } ...
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2answers
438 views

Geth 1.6.1 hangs throwing “unexpected fault address” fatal error

Since upgraded to version 1.6.1, Geth node hangs form time to time (once a week) with following fatal error: fatal error: fault [signal SIGSEGV: segmentation violation code=0x1 addr=0x7f6453b72c88 pc=...
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1answer
653 views

I'll never reach final block updating with geth, it's too slow

I´m updating my ethereum blockchain with geth. But I feel it is going really slowly. Each block is done in 1 minute, sometimes 30 seconds, but at this pace I'll never reach the final block, ...
2
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1answer
640 views

How is the block gas limit dynamically adjusted?

What mechanism lies behind adjusting the block gas limit dynamically? Is it the miner that mined the most recent block who decides whether to adjust the gas limit or not? How much can the block gas ...
2
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3answers
619 views

Why don't Ethereum increase the block gas limit?

Why don't Ethereum increase the block gas limit? In my understand, it can increase total throughput(transactions per second), but also increase uncle block rates either. But i couldn't find any exact ...
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1answer
793 views

Is Quorum production ready

Quorum is private permissioned blockchain network.Is it production ready or still in beta/Proof of Concept stage?
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1answer
1k views

Updating a Value in a Struct

Hi i am trying to update a value in a struct and i feel like i have tried everything. i think there is something important i do not know about using solidity structs. my contracts is defined as: ...
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2answers
193 views

Parsing contract method output as an array of fields

I have a constant method in a Smart Contract that returns this array: (uint256 _field1, uint256 _field2, uint256 _field3, address _field4, string _field5) When invoking it I got this hex result: ...
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1answer
118 views

What is the difference between create and newAccount in web3js?

There are two ways to create account one is web3.eth.accounts.create() and web3.eth.personal.newAccount(); function, When I use newAccount() function account is created in my local geth client but ...
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1answer
615 views

peers keep connects and disconnects into private Ethereum blockchain

I have two servers that are connected into local private ethereum blockchain successfully and they do mining as well. After few minutes one of them disconnects and after that it re-connects again and ...
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1answer
483 views

Can a contract read the address of past miners?

I am trying (in solidity) to write a contract that needs some statistics on the past few miners. E.g., who mined the last 100 blocks. I know that for the current block I get the address as explained ...
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1answer
394 views

What is the proof that Mainnet can't be reset?

It has been argued that the Morden testnet can be reset any time. How can one verify that this is not possible with the mainnet?
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1answer
14k views

Is there a way to track block synchronization progress in geth? [duplicate]

I just started up geth after importing my presale wallet. I'm getting a lot of block import messages like this: I0305 17:40:03.815435 10833 blockchain.go:1251] imported 256 block(s) (0 queued 0 ...
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1answer
414 views

Error in download full data with Geth ( transaction field in Block is empty)

I'm trying to download full data of ethereum block chain. But when I check the result, I found an error. From block 1 to 46146, field tx is empty,it means that there is no data for transaction. Does ...
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3answers
1k views

Storing data pointer on blockchain

How can I store user data on smart contract without exposing it to other nodes to read ? I read somewhere that you can store data pointers instead of data on contract and use it for offline data ...
4
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1answer
277 views

How can empty accounts with a nonce of zero appear on the blockchain?

Recently I have heard about zero balance accounts with a nonce of zero appearing on the blockchain. My understanding is that any account that has been used in a transaction must have a nonce greater ...
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0answers
165 views

Solidity benchmarking metrics [duplicate]

I am trying to figure out the best ways of benchmarking Solidity contracts. As with normal benchmarking, I presume one would basically want to measure computational effort and storage overhead: gas ...
3
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1answer
266 views

Blockchain syncs in Mist, but not in Geth?

I'm trying to mine. When I try syncing in Geth, all my handshakes fail and I cannot add peers. My port 30303 is open and syncing still doesn't occur with the --nat=none flag. Mist syncs no problem. I'...
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1answer
192 views

what is the use of difficulty in ethereum blockchain?

Why ethereum has introduce difficulty and what is the use of difficulty in blockchain? I have seen that we can use static difficulty for blockchain . So why we not use static difficulty for public ...
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1answer
114 views

Ethereum - Does it only have a single blockchain?

I still do not get if ethereum creators want it to be single blockchain or not? If not, where are instructions for creating my own blockchain to play with?
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0answers
137 views

Read function returning blank array in geth

I have deployed a smart contract on geth which has 2 simple read, write functions in it. Then I called the write function; e.g. payment.place_order("Laptop", 10,{from:eth.accounts[0]}). After the ...
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1answer
3k views

Block time and confirmation time

I have been reading in different papers and comments these two concepts and I would like to know the difference between them(if there is, sometimes it is a bit confusing). I understand that the block ...
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2answers
8k views

Getting transaction history for a particular account

I want to get the list of all the transactions which have been performed by/on an account in my private blockchain. I tried using the function getTransactionsByAccount(accountAddress, ...
2
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1answer
948 views

Ethereum chain size

Currently I don't have an up to date version of the real/test net on my PC. I've tried to find a blockchain explorer that will show the size of the chain in GB. Specifically for Geth, or atleast for ...
2
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2answers
894 views

Where can the parity blockchain files be found?

On my Mac I am looking for the Parity blockchain file for the ropsten chain. I checked the following locations: ~/.parity and ~/.local but both directories don't exist. ~/.ethash contains 1gb sized ...
2
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1answer
121 views

When 2 blocks or more are distributed at the same time, but the longest one delayed

I have a problem understanding the concept of handling two or more blocks that distributed at the same time (in the blockchain network). As far as I understood, When I get 2 or more blocks at the ...
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1answer
229 views

How Ethereum consensus validates same transaction from different miners? [duplicate]

In an Ethereum node, my brief understanding regarding transaction flow is below. When a client initiates a transaction, all mining nodes receives this request. Based on gas price, miner choose to ...
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1answer
47 views

How could return events of specific args?

In my solidity contract, I just have one event which is: transferOwnerShip (uint id, address indexed newowner); and I want to filter the events log in order to retrieve only the events that belong ...
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3answers
1k views

authentication needed: password or unlock

We're using Microsoft Azure, and NodeJS on the server. When we address Microsoft Azure via NodeJS, sometimes we get the 'Password or Unlock' error. But when we use Truffle and address the same setter, ...
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1answer
2k views

web3.eth.blockNumber is undefined

I have a running blockchain on 128.230.208.73 . I have created local-node on my system using following commands: geth --datadir bkc_data --networkid 89992018 --bootnodes enode://...
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1answer
640 views

Fatal: Error starting protocol stack: missing block number for head header hash

I didn't check on the running Geth instance and when I executed a function that logs everything in the Blockchain, I had an error that the port I was listening to wasn't responding. I figured out that ...
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2answers
1k views

Deposit and withdraw from multiple accounts

I have a scenario of deposit the amount on a particular address and keep the record of the total amount deposited at this address. The same way one can also withdraw the amount from this address and ...
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1answer
43 views

Are the timestamps of blocks for Ethereum only accepted when they are monotonically increasing?

Are the timestamps of blocks for Ethereum only accepted when they are monotonically increasing? If yes, why? And why other blockchains like Bitcoin and other blockchains with shorter block time can ...
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0answers
83 views

Why is my node taking so long to sync? [duplicate]

I downloaded the ethereum wallet, and its taken a few days yet its still syncing. Im on block ~701,000 thus far. Is something wrong? Is it supposed to take this long?
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1answer
611 views

problem when deploy smart contract in Quorum using web3j

I'm using web3J when i try to deploy contract i get Error processing transaction request: Non-200 status code: &{Status:400 Bad Request StatusCode:400 Proto:HTTP/1.1 ProtoMajor:1 ProtoMinor:1 ...
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1answer
1k views

Ethereum Mining: Do miners get a fee AND create new ether as a reward? [duplicate]

So far what I get is that when I send ether or any contract via the ethereum network that I then have to pay for this transaction by paying gas (which again has a price in ether and so on). So miners ...
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2answers
894 views

One to Many relationship in Contract

If id(Eg:1) field in structure is not unique and different names are mapped with same id=1. Can all names mapped with id=1 could be fetched from blockchain? pragma solidity ^0.4.4; contract ...
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1answer
158 views

How do short confirmation times negatively contribute to blockchain security?

The Ethereum whitepaper states: The motivation behind GHOST is that blockchains with fast confirmation times currently suffer from reduced security due to a high stale rate - because blocks take a ...
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1answer
37 views

Is the following scenario doable by a smart contract?

I have 2 persons ( say A or B). They want to have the following agreement. Person ‘A’ specify a deposit (x coins ) for user ‘B’ under a certain condition with a future time lock ‘t’. If user ‘B’ ...
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1answer
241 views

How to connect with Metamask and Smart contract?

I am ready with my frontend design. I have only 3 files HTML, CSS, and JAVASCRIPT. So, I didn't create any project or DAPP to have other files. Now next step is to connect with metamask and smart ...
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1answer
2k views

Where can I start learning to develop Decenteralized apps? [duplicate]

I have been trying to understand this development process of making DaPPs using ehtereum from various sources, some of them are outdated because this technology is evolving pretty fast as of now. ...
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2answers
1k views

Can I use ICO (Initial Coin Offering) to fund for a non-blockchain project?

I did a fair amount of googling before posting. Let's just say, I am planning to create a yet-another-blog-engine which is noway related to blockchain. Can I use ICO (Initial Coin Offering) to fund ...
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1answer
254 views

How do I export ethereum blocks with quickblocks to a JSON file?

I am looking for how to export or save data from ethereum blocks in a json file using quickblocks.
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1answer
2k views

Transfer ERC20 Token using Ropsten Infutra with Web3

I created a contract token using the Ethereum.org token solidity code. It has a function called transfer to send tokens between accounts: function transfer(address _to, uint256 _value) I need to now ...
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1answer
195 views

What exactly is Ether currency in Ethereum? [duplicate]

What is exactly Ether currency in Ethereum? Is it a token or a set of some functions that generate some tokens? If so, how many of those functions exist and what do they do? Are they hardcoded in the ...
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2answers
1k views

What is the maximum number of blocks in a blockchain?

What is the maximum number of blocks in a blockchain?
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1answer
156 views

Synchronous call of external contract function in Solidity

I have two Solidity contracts, where contract Caller depends on a second contract Callee. Contract Callee provides a public view function which checks the validity of a string (e.g. an password), ...
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2answers
48 views

Integrate more then one user with one ethereum account

I have many users inside the organization and I want to use same ethereum account for all the users , but with different usernames, so it there anyway to do that ?