First, I want to make sure that a sufficient number of lightweight wallets are connected to the node.
There's very little use of BIP37 today, and it's not even served by default by modern versions of Bitcoin Core. The chance that anybody would even connect to you and supply filters to you is extremely low. It was always a terrible idea to begin with, giving ...
Unconfirmed transactions are relayed only once. If you were not online, you will only learn about the missing transactions when they are included in a block.
As you may know, Bitcoin employs a gossip protocol to relay transaction and block information. When a new transaction gets submitted to the network, the spender wallet will announce it to its ...
The memory pool (mempool) is not limited to a specific transaction count, but limited by the amount of data the deserialized transactions take up in the node's memory. The default memory pool limit is 300 MB. The limit can be configured by passing -maxmempool <n> where the n is the number of megabytes allowed.
The default mempool limit is 100MB. Not limiting at all would be a significant denial of service risk. Raising the limit will increase the performance of your node in some situations, lowering it will reduce the resource usage by a small amount.
27GB as of 2020-06-14
You yourself can check this via going to .bitcoin/blocks/index folder. Where .bitcoin folder is usually hidden folder on home when using linux.
It depends if you have pruned than the index folder might appear less in size. As of today my index folder is 105.4 MB since I've prune=1000 and it would remain the same in future as well.