What happens to the transaction data that doesn’t make it to the blockchain?

[Asiska02]

The memory pool of a node can only store a specific amount of data they’re programmed to hold onto and will be in the memory pool for the time being programmed for it to stay there. What happens to a transaction data that doesn’t make it to the block/blockchain after the time elapse for the node to hold on to it??

[BlackHatCoiner]

They simply dump it. If two weeks have passed (as a default value) and the transaction hasn't got into a block yet, they'll dump it to free space. I suspect that the transaction is removed from the overwhelming majority of nodes, but most importantly, from most mining pool's mempool.

[Charles-Tim]

They simply dump it. If two weeks have passed (as a default value) and the transaction hasn't got into a block yet, they'll dump it to free space. I suspect that the transaction is removed from the overwhelming majority of nodes, but most importantly, from most mining pool's mempool.

I think that depends from node to node, like on Bitcoin Core, it is actually 14 days as you commented. Also this can get frustrating, normally the central server or node will keep on rebroadcasting it especially if the person's wallet is sychronize with the blockchain, that is why it is better for such person to never let his wallet not to sychronize during the time for it not to rebroadcast over and over again.

I remembered I had a transaction unconfirmed for two months from February 2021 to beginning of April 2021 when the mempool was so congested.

Also it is good to use a wallet that supports replace-by-fee so if the transaction is not included into a block faster and getting longer, the person would be able to pump the fee so for it to get confirmed earlier than using previous fee.

[HeRetiK]

They simply dump it. If two weeks have passed (as a default value) and the transaction hasn't got into a block yet, they'll dump it to free space. I suspect that the transaction is removed from the overwhelming majority of nodes, but most importantly, from most mining pool's mempool.

I think that depends from node to node, like on Bitcoin Core, it is actually 14 days as you commented. Also this can get frustrating, normally the central server or node will keep on rebroadcasting it especially if the person's wallet is sychronize with the blockchain, that is why it is better for such person to never let his wallet not to sychronize during the time for it not to rebroadcast over and over again.

Good point about wallets automatically rebroadcasting transactions, potentially causing the transaction to stick around the mempools for longer.

IIRC Electrum "gives up" at one point and let's you manually decide whether to try again or to remove the unconfirmed transaction from your history for good. Not sure how Bitcoin Core and other wallet implementations handle it though.

[bitmover]

They simply dump it. If two weeks have passed (as a default value) and the transaction hasn't got into a block yet, they'll dump it to free space. I suspect that the transaction is removed from the overwhelming majority of nodes, but most importantly, from most mining pool's mempool.

That is not very common to happen,  but yeah it does.

Nodes have by default about 300mb of space for transactions,  which is about hundreds of blocks. Now  the mempool has 14mb (you can check in mempool.space)

It happened once to me
 I made a 1 sat/vtbye transaction when the mempool was more than 250mb.
it deopped a few days later. i just rebroadcasted the transaction with about 10sat/vbyte and it was completed