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15 votes
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Why will the v5 fork raise the min block size to 300,000 bytes?

@Jollymort will probably answer this better but the current dynamic size algorithm didn't work well with RingCT transactions. It worked well with non RingCT transactions, which were smaller. Once a ...
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13 votes
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What security risks are associated with accepting Instant Transactions?

The risk is that this transaction will not be included in a block, ever, and thus never pays the merchant. The risk are the same as with Bitcoin, since Monero uses the same type of PoW system, so you ...
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12 votes
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Does Monero use replace-by-fee?

There is no such system in Monero. Now, miners will mine transactions that have the highest fee/byte ratio first. But once a miner accepted a transaction in its txpool, it will not accept another one ...
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  • 34.6k
12 votes

What does "transaction failed" mean in simplewallet?

Once the wallet creates a transaction, it can fail at several steps. The first one is to be rejected by the daemon. This can happen if the daemon sees that transction uses already spent key images, ...
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11 votes
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How many transactions can fit in a block?

There is no easy answer, since both the block size limit and the transaction sizes are variable. currently, the block size limit sits at its low limit, which is 60 kB. A transaction size can range ...
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9 votes
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Will 2 minute block times discourage retail merchant adoption?

Actually, instant (well, speed of information) payment channels are possible with monero, even now (no protocol changes to monero necessary). First we will just start with one way payment channels. ...
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  • 3,120
7 votes

What does "transaction failed" mean in simplewallet?

Failed means two things happened: the wallet sent a tx, which was accepted by the daemon. sometime later, the wallet doesn't find it in the pool nor the blockchain. There are fixes for this in newer ...
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  • 5,656
7 votes
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How long are unmined transactions kept in the memory pool?

Transactions drop from the txpool: after 7 days if they were included in a block that was orphaned after 24 hours otherwise The orphaned block case can happen with invalid transactions, if they were ...
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6 votes
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Can I cancel a transaction?

No, not really. If you didn't include a big enough fee or something it will fall out of the mempool after a day or so, but there's no way to ask all the nodes that have your TX in their mempool to ...
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5 votes
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How can the network or monero community reduce the txpool size?

Not really. Rapid growth in hashrate would only be slightly useful short term until the difficulty retargets which happens rather fast. This is only because you'd reduce the time between the blocks ...
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5 votes
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Why does proposed transaction fee fluctuate heavily sometimes?

Output selection is random. That is, simplewallet will pick one random output in your available outputs list, then again, and again, until the total is enough to satisfy the amount to send plus the ...
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  • 34.6k
5 votes

Why does proposed transaction fee fluctuate heavily sometimes?

It all depend how much outputs are needed to build-up you transactions. A higher mixin transactions can result in a smaller size transactions because it so happened that it needed less outputs to ...
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  • 1,271
5 votes
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maximum number of transactions in memory pool

It really depends on the amount of RAM/swap you have. There is no code to stop accepting transactions at any point at the moment, and if you eat up all you can in a spam attack, your kernel will kill ...
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5 votes
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What is the rationale behind keeping transactions in the mempool longer after they were in an orphaned block?

Based on current transaction volume (and a small reorg) there does not appear to be a need for a 7 day period for such transaction (because they can be confirmed much faster. However if transaction ...
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4 votes
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What causes transactions to exit the Memory Pool?

Usually, a timeout, if the transaction could not find its way in a block within a day (the timeout is seven days if the transaction was added in a block which was reorganized away). Why the ...
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4 votes

Why are pools not mining large blocks?

Because it's not economic for the pool or miner. There's also a "hard" cap (which goes up with median) at 2x the median. If a miner mines a too big of a block, he loses some base block reward (...
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4 votes

Monero double spends in the txpool

First one to get in a block wins, there can be no other way as far as I understand. I mean, who has the authority to say which one came first? For this, we have PoW and the blockchain - to avoid ...
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4 votes
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Global index of output

You cannot. It will be set when the transaction is mined.
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  • 34.6k
4 votes
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can a transaction never enter txpool but be included in blockchain

Yes, you can include a tx in a block without it being in the txpool. If you mine the block and send it to other peers, they will request the transaction since they don't have it in their txpool and ...
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  • 34.6k
3 votes

How do fees affect tx priority and how did these specific high fee tx's sit unconfirmed for > 1hr

I asked the same question over on reddit, and although I did not get to the bottom of why these particular txs sat there so long, I did learn several things which may be helpful/interesting for ...
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  • 61
3 votes

Where is the mempool stored?

The transaction pool is not stored on the blockchain: it is the set of transactions that are used to feed new blocks. Nodes store it in memory, and a poolstate.bin file when the node exits. The wallet ...
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  • 34.6k
3 votes
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How to query the memory pool?

monerod has a get_transaction_pool RPC call: curl -X POST http://127.0.0.1:18081/get_transaction_pool -d '{}' -H 'Content-Type: application/json' This will return the current state of the tx pool. ...
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3 votes
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Calculating the cost of a double spending attack

It depends heavily on how much work has to be (provably) redone. If you act upon a transaction that has just hit the txpool, there is not work yet to be redone by a miner, so it's cheap. Same as for ...
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3 votes

Why are there transactions in the Mempool that are invalid or over 50 hours old?

how is that even possible? ... What is wrong with the other TX that don't get confirmed (over 50 hours old)? Transactions can stay in the mempool for 7 days if they are found in an orphaned ...
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3 votes
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Will Chained Mempool Transactions ever be possible?

in addition to janowitz answer, chained transactions in monero are currently impossible because inputs are referenced with an index ID that is created when the tx makes it into a block. Thus, in order ...
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  • 5,656
2 votes

Does Monero use replace-by-fee?

I'm fairly certain it does not as RBF is a mechanism to get around the fact that it is crippled at 1MB, and there is a danger the transaction will never get included due to full blocks and being stuck ...
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2 votes

Where is the mempool stored?

Is the mempool stored on the blockchain? As the name suggests the mempool is the pool of transactions that exist in memory on one or more nodes in the network. Typically these are transactions that ...
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  • 1,386
2 votes

Where is the mempool stored?

I'm not sure about the cli wallet, but the the GUI wallet shows the tx's in mempool that belongs to you. It's a relatively new feature so to try it out you either need to build the GUI yourself or ...
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