Are Miners free to exclude whatever transactions they want?

[dscotese]

Bitcreditscc suggested I ask Gavin Andresen, so Gavin, if you read this and have a reply, that would be helpful.

Gavin's proposal from 2012 includes the text "Mining pools and solo miners have already started implementing their own fee policies, and will, of course, be free include or exclude transactions based on whatever policy they like."

You people get emotional and stop thinking rationally. All you are saying is that we should be at the mercy of the top 10 pools because they produce the majority of blocks. ie everyone's ability to transact is in the hands of ten people.

LOL  @ quoting Gavin Andresen. Go ask him now if he thinks it's a good enough idea to make it protocol.

Granted, bitcreditscc has slightly misrepresented what "you people" are saying since the "top ten people" will most likely never be "the miners", but his interest in the subject is still warranted.  Is there any protection built into the protocol that would prevent miners from including or excluding whatever valid transactions they want?

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[TimS]

Miners can include and exclude whatever transaction they want from the blocks they mine. If they want to build upon previous blocks, though, they have to accept the whole block as-is.

What this means in practice is that each individual miner has very little control over what ends up in the blockchain. Even if e.g. the top 80% of hash power decided to exclude your transactions from their blocks, that'd just mean you have to wait 5 times as long for your first confirmation. Unless they're willing to reject blocks that contain your transaction; this could be a sort of 51% attack, but it's only effective if the colluding miners control >50% of the hash power.

[findftp]

Miners can include and exclude whatever transaction they want from the blocks they mine. If they want to build upon previous blocks, though, they have to accept the whole block as-is.

What this means in practice is that each individual miner has very little control over what ends up in the blockchain. Even if e.g. the top 80% of hash power decided to exclude your transactions from their blocks, that'd just mean you have to wait 5 times as long for your first confirmation. Unless they're willing to reject blocks that contain your transaction; this could be a sort of 51% attack, but it's only effective if the colluding miners control >50% of the hash power.

So to summarize, it's a non issue.
Thanks for clearing it up.

[cr1776]

Just to be clear, miners have always been able to pick and choose what transactions are included in blocks they mine.  It isn't something new.  Some have included no transactions, some tilt towards more free transactions, some set fee policies different than others.  The main limit is the size of the blocks.

With p2pool, each miner can set their own parameters and if you (as part of p2pool) mine the block, your parameters are used for that block.  The next block that p2pool mines will use the parameters that the person who mines it has set. This differs from other concentrated pools where the pool owner sets the parameters used.

[jonald_fyookball]

So to summarize, it's a non issue.
Thanks for clearing it up.

I wouldn't agree 100%.

The fact that miners can exclude transactions could
be problematic in certain situations.

[findftp]

So to summarize, it's a non issue.
Thanks for clearing it up.

I wouldn't agree 100%.

The fact that miners can exclude transactions could
be problematic in certain situations.

Can you explain why? In what situations

[jonald_fyookball]

So to summarize, it's a non issue.
Thanks for clearing it up.

I wouldn't agree 100%.

The fact that miners can exclude transactions could
be problematic in certain situations.

Can you explain why? In what situations

one situation is 51% attack where miner controls all the blocks for a while.

other is if users and miners can't agree on fees.

[findftp]

So to summarize, it's a non issue.
Thanks for clearing it up.

I wouldn't agree 100%.

The fact that miners can exclude transactions could
be problematic in certain situations.

Can you explain why? In what situations

one situation is 51% attack where miner controls all the blocks for a while.

I agree on this, although the possibility is very small since it will need a lot of hashing power.

other is if users and miners can't agree on fees.

I agree as well, but if the market can't agree on fees, bitcoin (and other crypto currencies) have failed in my optic.

[amaclin]

I agree on this, although the possibility is very small since it will need a lot of hashing power.

s/since/while

[findftp]

I agree on this, although the possibility is very small since it will need a lot of hashing power.

s/since/while

I'm sorry not natively english speaking. 

What's the difference? 

[amaclin]

What's the difference?

The difference is time.
You needed a lot of hashing power yesterday.
You need a lot of hashing power today.
But it does not mean that this is forever.

[findftp]

What's the difference?

The difference is time.
You needed a lot of hashing power yesterday.
You need a lot of hashing power today.
But it does not mean that this is forever.

Ok, thanks. I think I got it.
I probably misuse the term anyway since while since it is hardwired in my brain