Why does wallet.dat change?

[cjg]

I've noticed that wallet.dat changes even though I've not generated new addresses, carried out any transactions, etc.

Under what circumstances does wallet.dat change?

[willphase]

it stores the header of the highest block you've downloaded, so it can quickly request and validate the next block.  Otherwise, as you mentioned, most wallet modifications happen when you perform transactions.

Will

[Maged]

it stores the header of the highest block you've downloaded, so it can quickly request and validate the next block.  Otherwise, as you mentioned, most wallet modifications happen when you perform transactions.

Will

The reason we now store that in the wallet is so that you can swap wallets in and out and they'll know how far back they have to rescan. Before, you had to do a full rescan of the blockchain whenever you swapped your wallet back in and had a transaction to/from the wallet since you swapped it out.

[cjg]

Well, that explains it.

It just made me concerned because I was backing up my wallet.dat, but then I could see it had changed since the backup.

wallet.dat seems like a counter-intuitive place to keep information on the latest blocks.

[DDreez]

I think it would be much more user-friendly to actually CREATE, NAME and SAVE your
own wallets (prompt the first time you open the client). Imagine a family sharing the same computer and having to copy/move around a bunch of files all named wallet.dat. Unnecessarily tricky! I'm sure there are lots of plans on incoporating better wallet handling in future versions.