how to check an txid input coin has been spend or not ?

[bit_kevin]

Somebody send me 1 BTC to address with txid(t01). Than I spend this 1 BTC to somebody else with txid(t02), this address's amount should be empty.

Now I create raw transaction with txid(t01), than I broadcast it. How does other bitcoind node found it has already spend out? Review all transactions after t01 to check?

[jackjack]

I didn't check the source code about that part but I think so...
I'm interested too btw

[🏰 TradeFortress 🏰]

There is a pool of unspent outputs.

[bit_kevin]

There is a pool of unspent outputs.

a pool of ALL unspent outputs ?

[🏰 TradeFortress 🏰]

There is a pool of unspent outputs.

a pool of ALL unspent outputs ?

Yeah. ALL unspent outputs. I'm not sure how to query it.

[Zeilap]

There is a pool of unspent outputs.

a pool of ALL unspent outputs ?

Yes, you can see its size with the command 'gettxoutsetinfo'.

Yeah. ALL unspent outputs. I'm not sure how to query it.

You don't, at least not without modifying the client to add a new RPC command.

[jackjack]

Where is that pool? Disk? Not RAM I suppose...

[Zeilap]

Where is that pool? Disk? Not RAM I suppose...

LevelDB (it's what the chainstate directory is for). It's partially cached in RAM though.