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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34 views

Is there a way to know how good a miner is choosing its transanctions to be mined from a fee maximization point of view?

Well, this is the way I've tried: When a mined block arrives to my node, I compare it against a transaction selection algorithm using my mempool. (I know my mempool it's different than the miner's one,...
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If we allow zero fee transactions within new policy rules for package relay why not also allow zero satoshi outputs?

In the proposed package relay the requirement that a transaction must meet the minimum relay fee rate is relaxed (the fee rate can be zero by the new policy rules) as long as the package in its ...
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How to fetch the last month's block and transactions from mempool?

I want to fetch last month's block and transactions from mempool using typescript. And then persist this to MongoDb. In mempool API-REST there is a code of "GET_Block". import mempoolJS from ...
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55 views

Validate raw transaction hex without broadcasting

I would like to check the validity of a raw transaction (i.e. whether it would be accepted by network nodes), without broadcasting the transaction to the network. I am interested in knowing what is ...
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3answers
672 views

Why is a synchronized mempool necessary in the network?

My understanding is that nodes maintain a mempool of unexecuted transactions. They use a bloom filter to query other nodes for transactions they do not currently have in their own mempool... thus ...
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Huge dependency graphs for transactions in mempool

I'm creating a web page to monitor bitcoin mempool https://mempoolexplorer.com/ and I've realized that sometimes exists huge transactions dependency graphs in the mempool. I'm talking about +-700 ...
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17 views

Connection Reset after sending mempool message

I build a python script to talk to bitcoin test nodes. When I'm sending mempool messages, my connection is getting is reset. Also sometimes when connecting to Jimmy Song's testnet node (testnet....
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49 views

Why does Bitcoin Core store the block height and the time of each transaction in the memory pool?

...given that one can be derived from the other? Surely the unsigned integer of height would be sufficient without the addition uint64_t of the time (to the second), wouldn't it?
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67 views

After mining rewards go down to 0, can someone clog the Bitcoin network by creating millions of transactions with no fees?

After mining rewards go down to 0, it is possible miners will not pick up transactions with 0 fees. In that case, could someone create millions of transactions with no fees, to congest the mempool and ...
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80 views

Error 400 when pushing tx hex to mempool.space's API

I am using the code syntax provided by mempool.space for a POST transaction request from their website here: https://mempool.space/api const mempoolJS = require("@mempool/mempool.js") const ...
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297 views

Is the `mempool` message reliable?

According to https://github.com/bitcoin/bitcoin/blob/master/src/net_processing.cpp#L3775-L3801, it seems like the mempool message is only responded to in certain cases. Can someone help understand how ...
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41 views

Unbroadcast count doesn't change as expected after 15 minutes

Related question: Test that mempool reattempts delivery of locally submitted transaction I tried running hidden RPC mockscheduler, I think it worked that day after relaunching nodes few times and ...
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Test that mempool reattempts delivery of locally submitted transaction

Test: https://github.com/bitcoin/bitcoin/blob/master/test/functional/mempool_unbroadcast.py I am trying this manually with below steps: Run two nodes (regtest): Node1: bitcoind -port=18333 -rpcport=...
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Reorgs and MEV in Bitcoin

Recently one of the altcoin that has lot of other issues is in news because of MEV (Miner Extractable Value). Honestly I don't care if someone exploits it or it affects the altcoin in any other way. ...
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48 views

Making regtest's generatetoaddress work with blocksonly=1

I'm setting up a regtest scenario in which I want to send transactions which should be included in new blocks created via the generatetoaddress RPC call. However, I want to disable transaction ...
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57 views

Can I transfer some BTC with 0 tx fee now, when the mempool is empty?

I wanna send a tiny amount of BTC (0.001BTC). I am not in a hurry and I noticed the mempool is sometimes empty these days because the market is cold. So can I set the network fee to 1sat/byte or even ...
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337 views

What happens if nSequence is set to 0x00000000?

I know setting nSequence 0x00000001 means the transaction is not valid until 1 block has elapsed since its's prevout confirms. At most one spend per two blocks. What happens if it's set to 0x00000000? ...
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42 views

A question about CPFP relaying policy

Let's say I broadcast a transaction tx0 signaling RBF replaceability. Later on, send another transaction tx1 that spends the same inputs of tx0, but this time with higher fees. In this case, tx0 is ...
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42 views

what happens to low-fee or forgotten transactions

If a transaction has a fee that is too low then it is possible for the transaction to either age out of the mempool (14 days) or get removed because the mempool reaches its max size. So what happens ...
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99 views

How to save the mempool information immediately before the node receives a block?

I want to use Bitcoin RPC API 'getrawmempool' to save the snapshot of the mempool immediately before my full node receives a block. This requires modification of the Bitcoin source code. How should I ...
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Sent transaction on 30 march 2021 still unconfirmed in mempool what can i do? [duplicate]

I made small BTC transaction from my bitcoincore wallet to account of Binance on March 30, 2021. I did set the fee low. But i wait a month for the transaction to back to my wallet. But it said still ...
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165 views

How are txns sorted correctly in Merkle trees between nodes and validated via Proof of Work

I am interested in exactly what happens to transactions in the pending block (block that is being mined at the time). From what I understand, transactions are the stored as a Merkle tree hash inside ...
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696 views

Why does the mined block differ so much from the block template?

I am looking at the specific block at height 680175. At the time when the block was not mined yet, I received the block template via bitcoin-cli getblocktemplate '{"rules": ["segwit&...
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TX Validation: Can a miner choose specific tx to validate from mempool? [duplicate]

I have made two TXs few days back and they remain unconfirmed so far. Can I be a bitcoin miner and validate them myself? And what happens if it remains as it is? There are some big amount of utxo ...
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Miner's pool and Mempool relationship

I am wondering why we need Mempool (central and aggregated pool) while each miner has its own pool? If we need the Mempool as an architectural design, how we can make sure that miners are sending ...
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157 views

How can an output be spent while the transaction is in mempool

I have seen transactions on a block explorer where the transaction is in mempool (unconfirmed) but one of the outputs already appears as spent, I am curious how this works. This question is a ...
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45 views

What is the difference between the txsize in mempool and mempool dynamic usage?

There is a table for the txsize in mempool and dynamic memory usage of mempool on statoshi.info's mempool overview? The default size of mempool defined in Bitcoin is 300MB, so is this default size the ...
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63 views

Where can I get a list of stale RBF'd transactions?

I would like to prove that a certain transaction was in the mempool on a certain date before it got replaced via RBF with another transaction. Is there any service that provides this data?
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225 views

Trying to understand the mempool and how transactions are picked

I am very new to blockchain and try to understand it completely. What I think I understood is, that every transaction is going to the mempool first and these transactions are getting picked by miners. ...
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Bitcoin Transactions confirmation [duplicate]

I'm new to crypto trading and id like to know if bitcoin transactions have ever taken more than 7 days to confirm? kind regards rob
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1answer
113 views

Does my node rebroadcast its mempool transactions on startup?

Say my node has transactions in its mempool and then gets shut down and restarted. Does it save the mempool to disk and reload this mempool when it starts back up, or does its mempool get lost on ...
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201 views

Will nodes configured with a larger-than-default mempool automatically retransmit transactions that have been dropped from the default mempool?

If a transaction is sent and dropped from the default mempool before it is included in a block, but nodes with a larger-than-default mempool size exist that still have the transaction, will those ...
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Sending less than 0.001 BTC from my Bitcoin Core Wallet not in memory pool

I recently managed to recover my wallet.dat and passphrase and have been trying to send the 0.00126913 BTC balance from my Bitcoin Core wallet into my Binance account, however the transactions stay ...
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156 views

Bitcoin transaction failed to broadcast (code 66)

I am using bitcoind. I got this error while trying to send a transaction: CommitTransaction(): Transaction cannot be broadcast immediately, mempool min fee not met, 6835 < 7865 (code 66) The ...
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35 views

What unconfirmed transactions in Mempool get into a block? [duplicate]

I have a question regarding picking unconfirmed transactions from the mempool. Let's say, there are 1000 transactions in the mempool. Can I randomly select some transactions, say, transaction a, b, c, ...
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91 views

Where in ~/.bitcoin are mempool and UTXO pools written?

Where in ~/.bitcoin are the two pools in question stored when their size grows above the size set by dbcache and maxmempool in bitcoin.conf. Is UTXO pool written to such location at Bitcoin Core's ...
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60 views

Do miners mine their own transactions or submit them to the network?

I am wondering how miners are behaving toward their own transactions. Do they send their own transactions to the mempool or can they process/confirm them directly? I am assuming that the miners are ...
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154 views

How to choose the transactions for a block?

From my understanding, the memory pool (or transaction pool) contains "open" or "unconfirmed" transactions that have to be validated and can be chosen (arbitrarily?) to be part of ...
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323 views

Unconfirmed transaction for 6 days now. need assistance for using CPFP

I have an unconfirmed transaction that has been sitting there for 6 days now. The fees only got higher sins i've made the transaction and i do not feel comfortabel waiting. I'm unable to use RBF sins ...
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46 views

Why are the drops in mempool unconfirmed transaction count not of constant height?

I was just browsing the following mempool visualization and couldn't come up with a good explanation why the drops in unconfirmed transaction count are not of pretty much constant height but vary ...
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1answer
366 views

What is the network mempools unconfirmed transaction expiration time?

I sent a bare $1000 multisig transaction using sendrawtransaction with a too low fee. When I create a new transaction with a higher fee, I m getting txn-mempool-conflict error, and when I use the ...
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2answers
291 views

Why can't default minimum fee rate be changed to 0.1-0.2 sat/vByte?

Main question (focus on this incase you are looking to close it as "needs focus"): Why can't we change default minimum fee rate to something below 1 sat/vByte? It was done in past: https://...
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54 views

Which tool can I use to calculate the best fee for a specific time?

Let's say I'm okay with a transaction to be included in a block in about 24h. The fee is obviously dependent on the network congestion. Which (online) tools can I use to calculate the optimal fee ...
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107 views

Where can I find a survey on different fee estimation algorithms?

I am looking for a comparison or summary of different fee estimation algorithms. Does anyone know of one? I would like to see what the best starting point is in order to see where optimization can be ...
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1answer
49 views

Better fee estimation and fee/tx/mempool management in wallets

Right now mempool has 65 MB of transactions waiting for miners to be included in blocks. 90% of the transactions are below 10 sat/vbyte. I am observing this trend from last few days and think it will ...
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193 views

Change -mempoolexpiry in BitcoinCore 0.20.1

I have accidentally made a transaction with a very low fee (5 sat/byte) and I doubt that it will be confirmed any time soon. Replace-By-Fee is not available since my transaction has no change. Abandon ...
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340 views

Transaction being ignored by miners, I mean Ignored, Not "not mined because low fees"

I'm working on a project to visualize the mempool and (also) check if a transaction is being ignored by miners. I have my own mining queue, to compare "my first block" with the block that ...
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814 views

Can you explain some of the dynamics that drive the variations in mempool depth?

I often see mempool graphs such as Jochen Hoenicke's that show significant fluctuations in mempool depth and hence the fee needed to get into upcoming blocks. Can you explain some of the dynamics that ...
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130 views

DumpMempool() and LoadMempool() in src/validation.cpp

My understanding is that DumpMempool() saves the memory pool state (unconfirmed txs received from other peers and if any txs broadcasted from this node) to disk and LoadMempool() is used if this state ...
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121 views

How do I get new unconfirmed transaction from mempool?

I know there is a function that allows me to see all transactions that are in mempool, but is there a way to see every new transaction that enters mempool? Like log to file whenever new unconfirmed ...