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Questions tagged [mempool]

Every node has their unique memory pool in which it tracks unconfirmed transactions. Use this tag for questions on how transactions enter and exit the mempool, how the mempool is delimited and other aspects of how it works.

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What happens when transaction bandwidth is exceeded?

A search for definitive information turned up literally nothing, so, what happens when transaction bandwidth is exceeded for an extended period? After a period of two weeks (default) transactions are ...
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33 views

How to avoid conflicts in a peer-to-peer topology (Bitcoin)?

For example in Bitcoin, if I want a miner to verify whether other miners store a transaction, before deleting it from his mempool. How can I handle the case more than one miner doing the verification ...
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Getting transactions from mempool to block

I have a question about getting transactions from mempool to be added to block. Imagine the situation where we have 500 transactions in mempool, when we decide that is enough to start adding them to ...
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Each full node has different mempool?

I don't understand if each full node has different mempool inside. With RPC command getblocktemplate I can Get the information about candidate block. I can Find all transaction verified but ...
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On the Bitcoin testnet, will transactions with higher fees get mined quicker?

I wonder if anyone here has spent enough time on the Bitcoin testnet to give me some insight on how the market forces there work. I am a teaching assistant in a university blockchain course with ~75 ...
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179 views

How to cleanup mempool

I want to cleanup mempool. I googled and knew -zapwallettxes might clean up mempool. But when I do the following command, mempool is still loaded. ./bitcoind -testnet=3 -server -rest -dbcache=4000 ...
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The question about “failedTx set” after add TX to new block done

Try to understand the whole process of mempool working. There is one thing I can't figure out: after add TX to new block done, how to deal with those TXs in failedTx set (those TXs add to failedTx ...
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42 views

Why some transactions disappear from the mempool?

Just before block 537562, I had the following transactions in my mempool: 'a4ca904361952c8a27bcf1fd36e5bc8ccdc5d42ceb72cfba60c017fb9cbbb0e5' '...
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What is the difference between Compact Blocks, Thin Blocks, Xthin and Graphene Compression?

What is the difference between these block propagation techniques in terms of size / bandwidth & computation requirements and also compatibility & reliability? All the above techniques try to ...
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41 views

Will every message x reach all connected peers in time t?

I've asked similar question here: Is gossip protocol in Bitcoin perfect? But I didn't get an answer to my question really. I am ideating a consensus algorithm and I need definitive answer. Can we ...
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202 views

How are the transactions chosen from the Mempool if every node has its Mempool?

I have this scenario: So whenever a wallet user is initiating a transaction, this goes as far as I understood into a Mempool. And that each node has its own Mempool. I have some questions though: Do ...
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224 views

get mempool transactions of some bitcoin node?

May I connect to any bitcoin core node, for example, this node 119.23.63.114:8333 using telnet and get its mempool transactions or even broadcast some transaction? I've read that section https://...
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What is the lockPoints in cTXMemPoolEntry for?

If a TX with locktime setting, before the locktime reached the TX will not be accepted by node to put into mempool. But for mempool there is a data member lockPoints seems related with locktime. What ...
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How “Transaction Package” in Mempool working?

Did a lot of research, still can't figure out: 1) how the Transaction Package in Mempool defined? 2) what's the process a new Transaction Package in Mempool constructed? Help me please and thanks.
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TX nLocktime and mempool

Where is a broadcasted TX located at before it's nLocktime reached? in mempool or not? I have tried a lot can't figure out. Help please.
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How does bitcoin deals with timing issues

How does Bitcoin system deal with that nodes are offline for a long time? Do the nodes have to get updated before participating in transactions again. Also, how does Bitcoin handle with all the ...
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102 views

How to return Tx to mem pool from orphan block

This question is centered around the implementation of how transactions on an orphan block return to the mem pool. In my understanding, once a block becomes orphan all it's transactions (that aren't ...
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Does a transaction in Bitcoin Mempool reach many miners during mining or only a single miner?

I'm trying to understand the logic around the Mempool. What I understand is a miner will pick transactions based on an incentive given by the sender, i.e. a fee, so that the higher fee, the faster ...
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is it possible to get mempool transactions as hex using bitcoin-core?

getrawmempool returns only TXID (verbose off), what I'm doing is calling getrawtransaction for each transaction ID to get a transaction hex. Bitcoin core doesn't support batch requests and each RPC ...
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Does a node validates a transaction that comes with a block if it's already in its mempool?

Except for checking for double spends, if there's a transaction in a block that's already in the node's mempool, it can theoretically skip its validation. Does it actually happen, or the nodes ...
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42 views

How can you send a transaction directly to the memory pool?

Is it possible to send a transaction to the bitcoin memory pool directly to have it mined without validating it?
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71 views

Transactions in a shorter blockchain branch

As I understand it, in a situation where two miners solve a block at the same time, a branch is created on the blockchain which is resolved when one branch is built upon, and thus becomes longer than ...
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340 views

How does the mempool work? What happens to the mempool when there are two equal length chains on the network?

Is there just one mempool or does each node keep a copy of the mempool? From my understanding each node needs to keep a copy of the mempool. If that is true then how is mempool consensus reached? ...
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How did these zero-transaction fee transactions make it into the Bitcoin network?

I thought someone said in this forum that the Bitcoin network screens out zero transaction fee-transactions because they are "dust" transactions and if anyone could submit zero-transaction-fee ...
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has anyone lost funds after performing -zapwallet to clear a transaction in bitcoin core wallet?

Ok so admittedly new to bitcoin but I'm a techie so not a complete noob. I was trying to make some purchases the other day with very small transaction fees that took too long to confirm and so my ...
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Why different pages report different number of mempool transactions? [duplicate]

I see different reports of transactions in mempool. From 35k (statoshi.info) over 170k (blockchain.info) to 215k (bitaps.com). All pages claim to report in realtime. Why is that? The difference is so ...
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What to do about “stuck” transactions? [duplicate]

(Copied from reddit) Hey. I recently made a bitcoin transaction for the first time in a while. The transaction fees have gone through the roof (!!) since the last time I used it, and I figured it ...
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Clearing 2 week old transactions from mempool

I can see a lot of questions posted on Reddit similar to "My transaction is not confirmed for X days. What do I do?". The most common answer is "Transactions are cleared from mempool after 2 weeks". ...
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Why is Bitcoin's unconfirmed transaction count rising and what effect does it have on the network?

I see that blockchain.info is reporting a large and steadily growing number of unconfirmed transactions. I assume that these are all transactions broadcasted to the network but never confirmed as a ...
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How to view a specific unconfirmed transaction with an online service? [closed]

Is there a web service out there that could show mempool transactions based on a specific filter (eg. arbitrary destination address)? Note: I expect a bitcoin client such as Electrum can do that ...
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1answer
1k views

Bitcoin transaction has been unconfirmed for over 24 hours… What should I do? [duplicate]

I'm pretty new to Bitcoin and although the technology is pretty exciting, I feel as though the sluggish confirmation times are letting it down... On 18th December I instructed a Bitcoin transaction (...
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1k views

I cann't send BTC on wallet Blockchain

When I try to send BTC i get error: BitcoindException(super=com.neemre.btcdcli4j.core.BitcoindException: Error #-26: 66: mempool min fee not met, code=-26). My wallet is on blockchain.info, I set ...
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420 views

Synchronize mempool between 3 nodes

Three bitcore nodes (version of bitcoind is quite old - 0.12.1) are deployed to the servers on different cloud platforms. All instances have the same bitcoin.conf files (except of rpcallowip, rpcuser ...
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Use bitcoin blockchain as a way to send messages to another address purposely setting a 0 fee or a very low fee?

Having that bitcoin nodes are all over the world. Is it possible to broadcast a transaction sending to 20 different addresses with a piece of the message embedded into each address? The goal is to ...
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152 views

Varying mempool statistics across multiple sources

I understand that each node is different and will have a different mempool (and size). But in looking at https://tradeblock.com/bitcoin/ it is showing a mempool size of around 20MB (http://...
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Is it possible to get CPFP information from full node, without requesting full mempool dump?

I want to get CPFP information out of full node - that is, ancestorsize and ancestorfees - in order to calculate the necessary fee for either CPFP, or RBF if possible. Can I get this information ...
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612 views

Transactions from Bitcoin-qt wallet not entering the mempool

I bought some BTC a few years ago and they've sat in an old Bitcoin-qt wallet (0.8.5) on a USB drive ever since. I'm hoping to transfer them out into Coinbase or something similar, but none of my ...
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93 views

How to create an inventory message and send it?

I am trying to create an inventory message of specific hashes that I select. Assuming I have all the hashes stored in a vector, how do I create the message 'manually'? (i.e stuff like getting total ...
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610 views

How much memory(RAM) is used by the mem pool and UTXO pool

I know I can set -dbcache=<MB> when starting bitcoind. Does this effect how much RAM is allocated for the UTXOPool or UTXOPool + mempool? How can I know how much RAM does each database take in ...
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Does miner with CPFP look through all the possible combinations of descendants to find the one with the highest fee?

When there is a transaction with more descendants, does CPFP policy look through all possible combination of descendants to consider "together", to find which one has the best fee? For example, when ...
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Does parent also pay for child?

One Bitcoin core mining policy is CPFP - child pays for parent. That is, transaction with high fee pays for its parent. Does it also work the other way - that is, does transaction with high fee pays ...
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100 views

What is `modifiedfee` in mempool dump, how is it related to actual fee?

In mempool dump through getrawmempool true, I see something called modifiedfee. It seems to be the same in all cases (just by looking at the dump). What exactly is it, how does it relate to fee (that ...
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1answer
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Why my bitcoin node does not show the same mempool size than a web blockexplorer?

It's supposed to match after a while. When several bitcoin nodes are running for days they should have the same mempool, but my bitcoind node shows arround 2k transactions less than blockchain.info ...
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262 views

What going to happend with transactions that is in both rejectend AND accepted chains?

I have been reading about blockchain forks and the longest chain situations and I cannot really understand what is going to happend in the situation when the transacton were included in both accepted ...
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3answers
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Why did the Mempool suddenly drop to zero

What caused the huge drop of the mempool from 60 MB to Less then 1 MB? These transaction didn't get processed there was no 60 MB block mined at the time. This occurred at 10:38 pm 29th August 2017 ...
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Why do I have more unconfirmed tx than getmempool info reports?

I presently have 39 unconfirmed tx that I've sent according to my local bitcoind: $ bitcoin-cli listunspent 0 0 | grep account | wc -l 39 (note: the above command gives the correct answer because ...
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461 views

Aborting/cancelling a transfer transaction

I'm running Bitcoin Core and I'm 7 days behind syncing currently. Last night, I initiated a transfer of some bitcoins to another person (He bought it from me) However, 4 hours later, he closed his ...
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Who is spamming the bitcoin cash mempool and why?

When looking at the last hours of bitcoin cash (BCH/BCC) transactions I saw a massive increase in low(or no)-fee transactions: Usually the graph looks similar to the BTC case (see below), just ...
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564 views

How to receive newly broadcasted transactions immediately with bitcoin-core RPC?

With getrawmempool it gets me txids, however it just dumps the whole mempool on me. This isn't convenient if I want to quickly detect new transactions. Is it possible to only get newly broadcasted ...
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Is it possible to set a dynamic -minrelaytxfee?

When I start bitcoind, I like to set a -minrelaytxfee to save bandwidth on transactions that will likely never make it in to the blockchain (because their fees are too low). However, when the network ...