Sub 1sat/vB transaction discussion and reversal of decision to mine them on solo ckpool.

Block 910440 is the first block that solo ckpool has mined that has included sub 1sat/vB transactions. I made this change because the bulk of the mining pools are now mining transactions below the default (until now) mempool policy of mining transactions only 1sat/vB or above. The reason for switching solo ckpool was partially out of necessity - if the mempool differs substantially from what other pools are mining, when other pools mine a block with low fee transactions, solo ckpool will be slow to build new blocks. The reason is because of the disparity in what is in the pool's mempool and it missing transactions included, so it would have to ask for the missing transactions before it can build a full block.

Now that solo ckpool has mined a block with sub 1sat/vB transactions I have data on the reward mined as the result of a low transaction fee period. Of the ~4900 transactions mined in this block, ~3300 were sub 1sat/vB transactions. It took some time to sift through the data of these transactions to determine what the mined fees were. They amounted to ~.0018 BTC more in fees, or ~$220. This is ~.06% of the current 3.125 BTC block reward.

These particular low fee transactions were very small and appeared to create 1-2 UTXOs each.

In light of how ridiculously small the extra fees mined were by accepting these transactions, and the potential for creating a significant number of new UTXOs, I am reversing my decision to mine these transactions. To maintain solo ckpool's ability to be aware of these transactions in the mempool I will only be setting the minrelaytxfee to accept and forward them, but not setting a lower blockmintxfee to mine them.

The block reward needs to have dropped substantially for such low fee transactions to add meaningful reward to mining pools, and I would only consider doing so if the reward was at least 1% more. The block reward would need to have dropped below 0.2 BTC total meaning we are decades away from such fees to be significant. By that time the landscape is likely to be very different to the current one, and it is unknown if fees will remain low that far away. A lower minimum fee is also likely to worsen fees' ability to be a significant contributor to mining rewards as block subsidy diminishes.

I implore other pool owners to do their own calculations and reconsider their decision to mine them at this stage.