why is it important to save the whole blockchain

[schnuber]

Hello
This is probably a dumbass question but I need some clarification.

To verify a transaction it is sufficient to get it confirmed by 6 blocks. So if six confirmations are normaly enough to confirm a block, why do we have to save the whole blockchain. Could we not just save let's say the last 1000 blocks of the blockchain and dismiss all that was before? Because the last 1000  blocks would be sure enough to prove the integrity of the blockchain.

Thank you

[caveden]

How do you know if an address has the money it needs to perform a transaction?

Plus, for the integrity of the chain, you must have at least all the headers. That's the only way to know which chain is longer.

[Gabi]

Because the blockchain contain all the transactions happened, it is needed to know how many bitcoins an address has. If you keep only the last 1000 blocks, then this info would disappear

It is true that not EVERY transaction is required, probably in the future the chain will be pruned to contain only the current situation of the addresses and not every transaction

[schnuber]

Ok I got it.
Thank you very much guys

[bitcoingenerat0r]

Try web based clients (blockchain.info) or the Electrum which store the blockchain in the cloud. Multiple server for the redundancy.

[truy]

Saving the whole blockchain multiple times (decentral) increases robustness too

[cp1]

If you're worried about the time it takes bitcoinQT to catch up, as the person above said there are other computer based wallets that don't require you to wait as long to get the blockchain -- multibit is another that wasn't mentioned.

[cp1]

Oh -- also you can torrent the blockchain to get started faster.

[madamamialin]

I'm a newb here so please don't flame me.
I'm not sure if there's a date of creation recorded for an address.
If so, we could check if the sender and receiver address is new (in the more recent blockchain)
Then there's no need to have all the previous blockchain

However, when we try to send to old address, we will face a problem...

[Gabi]

The chain only contain transactions.

Simply, the chain could only contain the last movements of the bitcoins. If i send bitcoins to address A and then to address B there is no need to keep in the chain the first transaction, it could be pruned and thus reduce the chain size  Maybe one day it will be done.

[cp1]

I'm a newb here so please don't flame me.
I'm not sure if there's a date of creation recorded for an address.
If so, we could check if the sender and receiver address is new (in the more recent blockchain)
Then there's no need to have all the previous blockchain

However, when we try to send to old address, we will face a problem...

If you created both addresses then you could record when they were created and that would be fine.  But there's no public record.  Addresses aren't actually created either, you just pick a random one to use.