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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TX Validation: Can a miner choose specific tx to validate from mempool?

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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19 views

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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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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19 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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40 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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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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56 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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189 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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67 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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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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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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41 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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39 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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248 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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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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272 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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219 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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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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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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40 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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152 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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how to get txid with sha256

I am trying to get a txId from a transaction without any bitcoin libraries. I can use low level libries though such as crypto, sha256 and so on. I have a class which contains version, vins, vouts, ...
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244 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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492 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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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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68 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 ...
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382 views

Clarifying descendants/ancestors in error cases for too-long-mempool-chain

In practice I've seen two instances of the too-long-mempool-chain error when trying to send a transaction: When there are too many unconfirmed transactions chained together: "too many descendants ...
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Does the mempool size as reported by Blockchain.com include the size of txs only?

Does the mempool size as reported by (for instance Blockchain.com) include the sum of the 'size' of transactions only? Or does it also include the overhead (due to indexes, allocation overhead, ...
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Why are the fee value and modified fee value always the same?

I do not see any transaction in the mempool having differing values for the fee and modified fee fields. Does nobody modify or accelerate their transactions? How do transactions with modified fees ...
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68 views

How to recognize dependent transactions sitting in the mempool?

I am trying to find out the relation among dependent transactions in the mempool. I have already used the "depends" field and tracked the transaction ids to go through. But I still can not ...
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1answer
61 views

Does testmempoolaccept check all possible rejection rules?

Is there any rejection rule that testmempoolaccept will not check, or is it safe to assume that if it passes testmempoolaccept validation it will be at least broadcast? Mostly concerned about complex ...
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My unconfirmed BTC transaction on blockchain just disappeared [duplicate]

I had an unconfirmed BTC transaction on blockchain.com for about 2 days plus and now I log in and there's no transaction again. I checked blockchain.info using the hash; all wiped nothing is showing, ...
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46 views

What valid transactions are not broadcastable?

Many valid transactions are not broadcastable by default in bitcoin core to avoid attacks that could harm the network. These would rarely be found in a node's mempool but could, however, be found in ...
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How to accelerate mempool data access with bitcoind

What could I do to accelerate access to the data I get when I call for example: bitcoin-cli getblocktemplate ? If I would like to be able to be the fisrt one who get information about all the new tx ...
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83 views

What is the default number of transactions a full node have in its mempool?

Is there a default limit to the number of transactions a node can keep in its memory pool? Or do we have to explicitly declare maxmempool=xyz to restrict the number of transactions a node can have in ...
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677 views

What happens to transactions in the mempool when their parent transaction expires?

I was just reading the Coin Metrics Newsletter #53, and it included a section about the recent mempool congestion. After mentioning transactions that got evicted due to the network's queue of ...
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153 views

What if two people want to spend same input at the same time

Lets say me and my friend both have access to same private key which can sign some new transaction. What would happen if me and my friend broadcast transaction with same input at the same time to a ...
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51 views

How does having a large mempool and allowing a greater transaction ancestry set change the interaction with your peers?

Bitcoin Core by default allows up to 300 MiB of mempool data, and restricts unconfirmed transaction trees to an ancestry set of at most 25 transactions and 101 kvB of transaction data. Since these are ...
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Why is my mempool count so much lower than that of block explorers?

I have been running a full node for about two days. I wanted to get a list of all mempool txs (using getrawmempool false), and found that it only came back with around 3,000 even though all the block ...
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Can edit mining node pool transactions list?

if I have a mining node that is attached to a bitcoin mining pool, can edit the order of the transactions sent by the pool to be mined by my node, and edit it, and even add manually transactions to ...
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1k views

What if the mempool exceeds 300 MB?

The bitcoin mempool size is at 108 MB and still climbing according to chain.so. It is slowly approaching 300 megabytes, which is said to be the mempool limit for BTC. What happens after 300 MB?
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desktop btc wallet “bitcoin core” incorrectly shows the amount of my balance

I have "bitcoin core" win 10 - 64 installed. I haven’t opened my wallet for a long time and haven’t synchronized it. Once again I opened the wallet, the wallet synchronized with the network and I ...
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The difference between mempool “bytes” and “usage”

getmempoolinfo returns bytes and usage. Currently, the value I have for bytes is 1316363 and the value I have for usage is 4826112. I'm assuming that bytes is how much space these transactions would ...
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Question about transactions added to mempool

When bitcoin transactions are made, I know that they are put into the mempool. After certain transactions are added to a block and that block gets verified, what happens to all the other transactions ...
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46 views

Monitoring BIP125 transactions in the mempool

Let's say I have a transaction with txid=A which has bip125-replaceable=True. If I bump the fee the original transaction will be removed from the mempool and replaced by the new one, so how do I know ...
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123 views

Transaction Status: 0 / not confirmed, not in mempool

Trying to send BTC, but fail. The transaction is not in mempool. What to do with these and how to solve the problem? I already returned BTC canceled the transaction
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6k views

What is the meaning of “Position in mempool” for a transaction?

I am using Electrum as my wallet and when I am receiving a transaction, I see an attribute with the name "Position in mempool" and the value is "8.61 MB from tip". Since the ...
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What will happen if transactions are being generated by multiple person with same one private key?

Let's assume people got the same private key of 1 BTC amount(Unspent state) for somehow lucky. Let's call that wallet address is WALLET_A. So people trying to send all the balance to their each own ...