Txs have dependency relationships with each other, blocks have a byte limit, blocks have a sigop limit. Even if you assume all txs are valid with the context of a mempool, you cannot assume any subset is valid and you cannot assume that you have a consistent mempool by simply relying on the mempool message.

e

> On May 20, 2019, at 08:06, Oleg Gavrilchenko <Gavrilchenko@???> wrote:
>
> Why should I select of subset from mempool returned txs? I suppose, that txs are valid. And txs will be invalid relatevly rare.
>
> From: Eric Voskuil [mailto:eric@voskuil.org]
> Sent: Monday, May 20, 2019 6:05 PM
> To: Oleg Gavrilchenko
> Cc: libbitcoin@???
> Subject: Re: [Libbitcoin] FW: How use libbitcoin for get mempool information?
>
> Once you have the mempool txs how would you select a subset valid for the next block?
>
> e
>
> On May 20, 2019, at 07:20, Oleg Gavrilchenko <Gavrilchenko@???> wrote:
>
> I think, that my device can send mempool request to any full-node in bitcoin P2P network. And the full-node send new valid txs to my device. And then my device does not need to download full blockchain.
> Or am I wrong?
>
> From: Eric Voskuil [mailto:eric@voskuil.org]
> Sent: Monday, May 20, 2019 5:05 PM
> To: Oleg Gavrilchenko
> Cc: libbitcoin@???
> Subject: Re: [Libbitcoin] FW: How use libbitcoin for get mempool information?
>
> How would the node answering your request know what txs it could select if it didn’t have the chain?
>
> On May 20, 2019, at 05:40, Oleg Gavrilchenko <Gavrilchenko@???> wrote:
>
> I think, I need to send mempool request, get all new transactions and include its in new block. Or am I wrong?
>
> From: Eric Voskuil [mailto:eric@voskuil.org]
> Sent: Monday, May 20, 2019 2:06 PM
> To: Oleg Gavrilchenko
> Cc: libbitcoin@???
> Subject: Re: [Libbitcoin] FW: How use libbitcoin for get mempool information?
>
> How would you know which txs to select?
>
> e
>
> On May 20, 2019, at 03:47, Oleg Gavrilchenko <Gavrilchenko@???> wrote:
>
>
> Hi!
> Thank you for answer.
> I would like to clarify some things.
> 1. I need to have full blockchain or only full headers for new block generation?
> 2. Why do I need full blocks for new block generate?
> 3. How can I get block template and generate new block with libbitcoin?
>
> From: Eric Voskuil [mailto:eric@voskuil.org]
> Sent: Friday, May 17, 2019 8:57 PM
> To: Олег Гаврильченко
> Cc: libbitcoin@???
> Subject: Re: [Libbitcoin] FW: How use libbitcoin for get mempool information?
>
> No code can generate a valid block without maintaining the chain.
>
> e
>
> On May 17, 2019, at 02:02, Олег Гаврильченко <Gavrilchenko@???> wrote:
>
> Hello!
> I develop FPGA mining device and I don’t want use bitdoind. Bitcoind for work download full blockchain(300GB).
> I wand write lightweight cliend, without bitcoind, that get information from Bitcoin P2P similar like “getblocktemplate” request and if my device find bloc hash (J) send it to network.
> Say me please, how I do this with libbitcoin ?
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