Why no minimum # of TX in a block?

[prophetx]

Now that bitcoin gets a fair amount of use, why isn't their any logic built in to qualify each block not only with a nonce but with a minimum # of transactions?

for example check this out, it happened to be mined 1 minute after the previous block

https://blockchain.info/block-index/448193/00000000000000003108adad355650e57f214587c287cc5b0e9bb6da482b3b77

I know this would encourage different behavior like miners keeping some reserve transactions but there must be enough no mining fee tx floating around to meet that need 

[Remember remember the 5th of November]

The number of transactions in a block is determined by the max block size, which in turn is determined by the size of transactions. Also, the bigger the fee, the higher the chance the tx gets included in a block. But some miners might decide, hey, I want only high fee transactions, in which case max block size may never get hit, and only say 50 TXes get included in a block.

[prophetx]

The number of transactions in a block is determined by the max block size, which in turn is determined by the size of transactions. Also, the bigger the fee, the higher the chance the tx gets included in a block. But some miners might decide, hey, I want only high fee transactions, in which case max block size may never get hit, and only say 50 TXes get included in a block.

yes i know that, however that block which I linked has no tx other than the network subsidy

[grue]

What's preventing miners from adding a bunch of filler transactions to satisfy the quota?

[gmaxwell]

What's preventing miners from adding a bunch of filler transactions to satisfy the quota?

Nothing, which is why it would be pointless.

for example check this out, it happened to be mined 1 minute after the previous block

It was probably mined seconds after the prior blocks. The timestamps are only approximate.

[prophetx]

What's preventing miners from adding a bunch of filler transactions to satisfy the quota?

good point

[Remember remember the 5th of November]

The number of transactions in a block is determined by the max block size, which in turn is determined by the size of transactions. Also, the bigger the fee, the higher the chance the tx gets included in a block. But some miners might decide, hey, I want only high fee transactions, in which case max block size may never get hit, and only say 50 TXes get included in a block.

yes i know that, however that block which I linked has no tx other than the network subsidy

The reason for this is, because the block was found so soon after the previous, the mempool of the miner was empty at the time, i.e it didn't choose to not add TXes, it just happened.

[Quokka]

Now that bitcoin gets a fair amount of use, why isn't their any logic built in to qualify each block not only with a nonce but with a minimum # of transactions?

for example check this out, it happened to be mined 1 minute after the previous block

https://blockchain.info/block-index/448193/00000000000000003108adad355650e57f214587c287cc5b0e9bb6da482b3b77

I know this would encourage different behavior like miners keeping some reserve transactions but there must be enough no mining fee tx floating around to meet that need  

The failsafe I guess you could say is the fact that miners benefit from including transactions in a block as that means they get paid the fee (Assuming there is one). So fortunately there shouldn't be a situation where miners are deliberately mining transactionless blocks. Occasionally it happens by pure chance but that's just the random nature of block generation.

Of course I suppose you could argue that a miner might mine transactionless blocks in order to cut down on the block size for faster propagation, but that'd seem pretty counter productive.

[Rannasha]

So fortunately there shouldn't be a situation where miners are deliberately mining transactionless blocks. Occasionally it happens by pure chance but that's just the random nature of block generation.

Of course I suppose you could argue that a miner might mine transactionless blocks in order to cut down on the block size for faster propagation, but that'd seem pretty counter productive.

Except that it isn't necessarily counterproductive to mine empty blocks to get faster propagation. The propagation time depends on the number of transactions in the block, so a miner could make an estimate of the odds of a block being orphaned due to slow propagation and weigh the potential losses of an orphaned block against the certain losses of not including fee-paying transactions.

With fees still being a very small part of the block reward, the answer may not be obvious.

[Quokka]

Except that it isn't necessarily counterproductive to mine empty blocks to get faster propagation. The propagation time depends on the number of transactions in the block, so a miner could make an estimate of the odds of a block being orphaned due to slow propagation and weigh the potential losses of an orphaned block against the certain losses of not including fee-paying transactions.

With fees still being a very small part of the block reward, the answer may not be obvious.

True, let's look at the numbers on that. According to Blockchain.info's orphan block graph (And I qualify this by saying that I don't know how accurate this graph is) you could pretty reasonably estimate that the odds of a block being orphaned is close to 2% (144 blocks a day, around 2 or 3 are orphaned per day). So as long as transaction fees are worth at least 1/50 of the block reward there shouldn't be any significant motivation to mine empty blocks. Currently that would mean .5 BTC worth of transaction fees per block, and as you said currently the fee per blocks is generally much smaller than that.

Is my math right on this?

EDIT: I just realized that I forgot to account for the fact that sending an empty block does not completely remove the possibility of that block being orphaned. Unfortunately I don't know exactly how one would calculate the odds of a block containing transactions being orphaned vs. the odds of an empty block being orphaned.

[PolarPoint]

It would be better for the bitcoin network if we introduce a rule to require a block to contain a minimum number of transactions. If all miners decide to "strike" and mine without any transactions, the bitcoin network will be at a stand still.

[gmaxwell]

11 posts in and we've gone full circle already!

He's probably just blindly posting without reading any of the messages in order to get his signature spam more widely distributed.

I'm going to lock this thread since it seems like the question was asked and answered and isn't making any more progress.