Differences between wallet.dat file back up from different time

[RapTarX]

What’s the difference if I have my wallet.dat file back up from 2020 for instances and a back up from 2021? If I'm correct, I'm still able to recover my all fund received till now from the 2020 back up file. What will I miss if I use the 2020 back up file for recovering the wallet? This is something I'm little knowledged; in fact I'm comfused.

[ranochigo]

Previously, Bitcoin Core generates the addresses randomly, 100 addresses at a time is maintained. That requires the user to backup their wallet every 100 transactions.

Afterwhich, the hierarchical deterministic mode is introduced and allows the wallet to generate addresses based on a fixed seed. You only need to backup your wallet once, unless you did a password change. There should be a HD symbol at the bottom right to indicate whether it is a hierarchical deterministic wallet or not. Wallet files are backwards compatible.

A slight correction, was just reading through my posts. Core actually generates the address as soon as an address is taken out from the keypool so that the keypool always maintains at least 100 or 1000 (depending on version or your own configuration). The rule of thumb is to have a backup every 100 transactions so even if your data is lost at the 50th transaction, you still can restore your wallet using the wallet.dat as all of the 50 addresses used were in the keypool when you made a backup at the start.. Note that this applies to both sending and receiving(with a new address), Core uses change address which makes for an extra address being used from the keypool. Ideally, I would overlap the wallet.dat, so I'll probably back it up every 90th transaction or so, just in case I forget.

Good thing is, HD wallet still contains a keypool but the addresses are generated from a seed, which as I've highlighted doesn't change unless you were to change the password. In the case of a password change, the keys from the keypool are dumped into the new wallet.dat and new addresses are generated in the keypool from a new seed within the wallet.dat. That is why you have to back up the wallet after a password change.

[nc50lc]

-snip- What will I miss if I use the 2020 back up file for recovering the wallet? This is something I'm little knowledged; in fact I'm comfused.

AFAIK, just the labels that you've set after the backup.

You're right about the funds since it should be an "HD wallet" if it's a wallet created on 2020,
considering that you're using the latest Bitcoin Core version at that time.

[hugeblack]

wallet.dat is a recovery file generated by bitcoinCore, so talking about the years is not as meaningful as talking about bitcoin Core versions that generate those files.

AFAIK, since Bitcoin Core 0.13 there is no substantial changes in the way data is recovered.
anyway read this for more ----> https://bitcoin.stackexchange.com/questions/61024/how-do-i-migrate-my-bitcoin-core-wallet-to-an-hd-wallet/61025#61025