What is the default number of transactions a full node have in its mempool? Is there a default limit to the number of transactions a node can keep in its memory pool? Or do we have to explicitly declare maxmempool=xyz to restrict the number of transactions a node can have in its memory pool?
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 &lt;n&gt; where the n is the number of megabytes allowed.