On 15 November, the Bitcoin mempool saw its biggest flood since January 2018, with the mempool size hitting 94 MB at one point. However, it only took two days for the mempool to completely clear out in this case. This situation is a testament to the efficiency of the Bitcoin network.
The mempool is all of the transactions that are unconfirmed, meaning they have not been included in a block yet. The mempool periodically spikes to 5-15 MB, but this week 90,000 transactions totaling 94 MB flooded in all at once. Apparently this mempool flood was caused by a Bitcoin user consolidating all of their dust transactions.
Essentially, over time a Bitcoin wallet can build up dust in it, which is small transactions on the order of 1-100 satoshis, where a satoshi is the smallest unit that a Bitcoin can be divided into. Dust is accumulated due to transactions leaving all but 1 satoshi in a Bitcoin address for example.
Due to network fees, this dust is usually inaccessible, but due to a slowdown in Bitcoin activity fees have recently dropped low enough so that users can profitably consolidate their dust. This is why a Bitcoin user decided to consolidate nearly 100 MB of dust transactions all at once on 15 November.
Fortunately, network activity remained low, so it only took two days for all of these dust transactions to be confirmed and leave the mempool. This shows that the Bitcoin network is currently highly efficient in clearing out large mempool backlogs.
Image Courtesy: Pixabay