Bitcoin Forum

Bitcoin => Development & Technical Discussion => Topic started by: genjix on May 07, 2011, 12:33:22 AM



Title: Limit on transaction speed
Post by: genjix on May 07, 2011, 12:33:22 AM
Hey,

I met a web designer guy who last night made a point about the number of transactions being limited because of the block size. I did some calculations. Can somebody confirm these numbers for me?

MAX_BLOCK_SIZE = 1000000 bytes

Average transaction = ~200 bytes (conservative lower limit)

Average number of tx per block = 1000000/200 = 5000

Each block has an interval of ~10 mins

that means 5000 confirmed tx / 10 mins OR 500 tx / min OR
8 tx / s

---------------

Visa must do thousands of tx a second or maybe more.


Title: Re: Limit on transaction speed
Post by: Garrett Burgwardt on May 07, 2011, 12:34:36 AM
When we start bumping up against the top of the block size limit, we can raise it. Until then it's just low to prevent spam.


Title: Re: Limit on transaction speed
Post by: slurch on May 07, 2011, 12:36:36 AM
Here's a good article on the wiki:

https://en.bitcoin.it/wiki/Scalability (https://en.bitcoin.it/wiki/Scalability)


Title: Re: Limit on transaction speed
Post by: genjix on May 07, 2011, 12:41:08 AM
When we start bumping up against the top of the block size limit, we can raise it. Until then it's just low to prevent spam.

Wouldn't this fork the chain? And don't you need the mutual agreement from loads of differing clients that might not upgrade simultaneously?


Title: Re: Limit on transaction speed
Post by: Garrett Burgwardt on May 07, 2011, 12:47:34 AM
There was an upgrade before, where the software was set to change to the new protocol after block XXXXX, and it was far enough away that most people upgraded before then.


Title: Re: Limit on transaction speed
Post by: genjix on May 07, 2011, 03:03:39 PM
I'm skeptical of this happening. Right now it's easy to upgrade while the community is small and people download their client from one source.

But once everybody is running different flavours of Bitcoin, network-wide upgrades are not a solution.

Take a look at ipv4 and ipv6 today. The internet runs slower, less secure and is running out of addresses but nobody upgrades. Eventhough there's been many years to enable ipv6 and the running out of ipv4 addresses was well predicted in advance.


Title: Re: Limit on transaction speed
Post by: grue on May 08, 2011, 12:27:29 AM
I'm skeptical of this happening. Right now it's easy to upgrade while the community is small and people download their client from one source.

But once everybody is running different flavours of Bitcoin, network-wide upgrades are not a solution.

Take a look at ipv4 and ipv6 today. The internet runs slower, less secure and is running out of addresses but nobody upgrades. Eventhough there's been many years to enable ipv6 and the running out of ipv4 addresses was well predicted in advance.
that's because ipv6 required an hardware upgrade.


Title: Re: Limit on transaction speed
Post by: genjix on May 08, 2011, 12:50:37 PM
How about banks though that are all running decades old software from the 80s?


Title: Re: Limit on transaction speed
Post by: caveden on May 08, 2011, 03:40:46 PM
I'm skeptical of this happening. Right now it's easy to upgrade while the community is small and people download their client from one source.

But once everybody is running different flavours of Bitcoin, network-wide upgrades are not a solution.

I share your concern, that's why I proposed this: http://bitcointalk.org/index.php?topic=1865.0

It would still need one backward incompatible change, but just one. Gavin once showed himself open to the idea, if somebody manages to implement it safely. Now we "only" need somebody good enough in C++ willing to give it a try...


Title: Re: Limit on transaction speed
Post by: Mike Hearn on May 10, 2011, 03:37:35 PM
I'm not planning on implementing block size checks in BitCoinJ. Most users will end up on lightweight clients that don't implement every single check, so it'll probably be OK.

That said I think we should be bumping up the block size sooner rather than later.


Title: Re: Limit on transaction speed
Post by: gigabytecoin on May 11, 2011, 10:24:58 AM
That said I think we should be bumping up the block size sooner rather than later.

Agreed.

Why not build Bitcoin so that it doesn't need to scale from the start?