NXT :: descendant of Bitcoin - Updated Information

[mcjavar]

What does this mean?


[2014-02-14 10:39:40.346] DEBUG: Will pop block 5073332198957728923 at height 66148
[2014-02-14 10:39:40.347] DEBUG: Will pop block 8348856438008341233 at height 66147
[2014-02-14 10:39:40.348] DEBUG: Reversal of alias assignment not supported
[2014-02-14 10:39:40.348] DEBUG: Popping off last block not possible, will do a rescan
[2014-02-14 10:39:40.349] Re-scanning blockchain...
[2014-02-14 10:39:54.734] ...Done
[2014-02-14 10:39:54.737] DEBUG: Generate block failed: Previous block id doesn't match

Jean-Luc?

[greyw00lf]

please, can i get some coin?  my nxt address is 1954727322887273577

thanks
im convinced in this currency

Hi ErosLp, you can use the faucet at http://nxtra.org/faucet to get your first Nxt
or take a look at http://mynxt.org/#nxt
or use exchanges to buy some Nxt: http://mynxt.org/#exchanges

[jl777]

Depends which cost function you take into consideration. The size of the block part occupied by a multi-transaction would still be O(n) as are n transaction. So, yes, it could be cheaper by a factor of 2 or so.

A key thing that Nxt *has* over its rivals is fast txs. If I have a tx with 100 outputs and 1 sig vs. 100 outputs and 100 sigs then the latter is going to be slower both in terms of data size and sig verification.

So I think that Nxt should allow such more compact txs in order to provide the "leanest and meanest" tx system in the crypto currency world.

Agreed. We might as well be the best in all areas.

[greyw00lf]

@JL

Code:

[2014-02-14 18:23:55.255] Database is at level 13
[2014-02-14 18:23:55.267] DEBUG: Will apply sql:
ALTER TABLE block DROP COLUMN IF EXISTS index
[2014-02-14 18:26:26.984] DEBUG: Will apply sql:
ALTER TABLE transaction DROP COLUMN IF EXISTS index
[2014-02-14 18:33:32.807] Updated database is at level 15

Didn't the additional indexes help?

Question: Is it possible to re-use the nxt_db directory when upgrading from 0.7.4 to 0.7.5  without downloading the whole blockchain again?

Raspis do have a tough time doing that, crashes 1-3 each time, must be restarted, takes severla hours in total...

I don't have problems downloading the whole blockchain with my RPi (not overclocked), no crashes, no restarts. It takes hours... hmm yes maybe 1-2 hours, but you don't have to do that on every update. The last time i did was when i switched to 0.7.2. From then i always copied the db to my new nxt-folder.

No, no. It does not. Just overclock it at medium level. Works like a charm for me.

And yes, you can re-use the db of 0.7.4.

In fact the nxt.log above shows the migration from 0.7.4 to 0.7.5.

I didn't overclock mine. To what CPU-rate did you overclock it? Do you use some kind of cooling? My RPi is just in an ordinary plastic-case, no cooling at all...

[jl777]

P.S. I am trying to make sure that even after NXT goes above $1000 we can still buy a lollipop at a precise price.

even if Nxt goes to $1000, 0.00001 would be 1 cent

Too many decimal points bring confusion.

How much does a single crypto cost? One that is .0000000013 BTC? I just want to be able to not have to worry about bundling very small valued things so we dont have the quantization problem.

The GUI can hide the extra precision. I am not talking about display. I am talking about what the low level protocol supports.

I am also not talking about reducing the fee to .00000001 NXT. The fee should be reduced an order of magnitude at a time as we find that it is a problem.

Reworking the code to add precision is the time where we can figure out how to add the most digits without adding too much overhead. We dont have to use or display that precision, but if we can get it essentially for free, why not?

James

[Jean-Luc]

Question: Is it possible to re-use the nxt_db directory when upgrading from 0.7.4 to 0.7.5  without downloading the whole blockchain again?

Yes, it is designed to be possible to upgrade without having to delete the nxt_db directory, that's the reason I bother with applying those SQL statements.

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

[Jean-Luc]

What does this mean?


[2014-02-14 10:39:40.346] DEBUG: Will pop block 5073332198957728923 at height 66148
[2014-02-14 10:39:40.347] DEBUG: Will pop block 8348856438008341233 at height 66147
[2014-02-14 10:39:40.348] DEBUG: Reversal of alias assignment not supported
[2014-02-14 10:39:40.348] DEBUG: Popping off last block not possible, will do a rescan
[2014-02-14 10:39:40.349] Re-scanning blockchain...
[2014-02-14 10:39:54.734] ...Done
[2014-02-14 10:39:54.737] DEBUG: Generate block failed: Previous block id doesn't match

This is all normal, works as intended. It is telling you exactly what is happening - popping off a block, doing a rescan because alias assignment cannot be simply undone in a pop-off. The block generation attempt failed because in the meantime another block arrived and was accepted.

[l8orre]

Thanks! I am reluctant about the overclocking, but I run it with -856xmx ...

What does -856xmx do?

It is the memory available to the jvm, I quoted it wrong:

ps -ax
 2040 ?        SNl   61:45 /usr/bin/java -Xms128m -Xmx856m -jar start.jar STOP.PORT=7873 STOP.KEY=0815


-Xms128m is the minimum that is reserved at the start, and -Xmx856m is the maximum it can have, in megabytes. I often had crashes with a maximum smaller 450MB, but with giving it almost all the memory, it runs quite good.

Except that dl'ing the whole blockcahin is quite some venture.

[l8orre]

Question: Is it possible to re-use the nxt_db directory when upgrading from 0.7.4 to 0.7.5  without downloading the whole blockchain again?

Yes, it is designed to be possible to upgrade without having to delete the nxt_db directory, that's the reason I bother with applying those SQL statements.

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

once the blockchain is complete 0.7.4 is running quite smoothly at 1-3% cpu, and given lots of ram:

top
                                                              
 2040 pi        26   6  993m 385m 2768 S   1,0 88,0  61:54.85 java                                                                      
 3318 pi        20   0  4880 1324  976 R   1,0  0,3   0:01.18 top        

I think also the blockchain download was faster with 0.7.4, but I can't really tell, because I did not monitor the dl all the time ...

[ChuckOne]

Question: Is it possible to re-use the nxt_db directory when upgrading from 0.7.4 to 0.7.5  without downloading the whole blockchain again?

Yes, it is designed to be possible to upgrade without having to delete the nxt_db directory, that's the reason I bother with applying those SQL statements.

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

What exactly do you mean by performance?

1) startup is slow as always. Especially these migrations

2) running is as good as always. Does not go above 5%.

3) RAM consumption is 1% lower. Still 87% of total memory.

[l8orre]

Question: Is it possible to re-use the nxt_db directory when upgrading from 0.7.4 to 0.7.5  without downloading the whole blockchain again?

Yes, it is designed to be possible to upgrade without having to delete the nxt_db directory, that's the reason I bother with applying those SQL statements.

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

What exactly do you mean by performance?

1) startup is slow as always. Especially these migrations

2) running is as good as always. Does not go above 5%.

3) RAM consumption is 1% lower.

yes, which is why having the option of using the nxt_db is quite helpful

[ChuckOne]

Not, if the runtime for calculating a sig is dependent on the number of bits of the payload.

It is a common misconception that basic operations are in O(1), but that's wrong. Even addition and multiplication of larger numbers take longer than of smaller numbers. The same hodls for sig function.

I like the conceptual idea of having set-based transactions because set-based thinking is one of the principle of modern computer science.

What I was trying to explain to you was that you should not make not unproven statements.
Show me the runtime complexity of the sig function in terms of payload length and we'll see.

NRS signs SHA256 of a message.

1 signature takes 100 times more CPU ticks than SHA256(32_random_bytes). Signing of a transaction that is 100 times longer ~ 2 ordinary signatures.

Not sure, I got it.

The runtime complexity is still O(n)? But the factory in between is 100? (n = number of bits)

[ChuckOne]

Question: Is it possible to re-use the nxt_db directory when upgrading from 0.7.4 to 0.7.5  without downloading the whole blockchain again?

Yes, it is designed to be possible to upgrade without having to delete the nxt_db directory, that's the reason I bother with applying those SQL statements.

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

What exactly do you mean by performance?

1) startup is slow as always. Especially these migrations

2) running is as good as always. Does not go above 5%.

3) RAM consumption is 1% lower. Still 87% of total memory.

yes, which is why having the option of using the nxt_db is quite helpful

Why is that? Or maybe, I didn't understand what you mean.

[l8orre]

Question: Is it possible to re-use the nxt_db directory when upgrading from 0.7.4 to 0.7.5  without downloading the whole blockchain again?

Yes, it is designed to be possible to upgrade without having to delete the nxt_db directory, that's the reason I bother with applying those SQL statements.

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

What exactly do you mean by performance?

1) startup is slow as always. Especially these migrations

2) running is as good as always. Does not go above 5%.

3) RAM consumption is 1% lower.

yes, which is why having the option of using the nxt_db is quite helpful

Why is that? Or maybe, I didn't understand what you mean.

when you update, you just dump the old nxt_db directory into the nxt_db in the unzip directory of the new version, and the blockchain won't be downloaded -just as with before, when you could just dump the blocks.nrs and transactions.nrs into the new version.
only then it would crash very often, and now with sql it hopefully won't.

At least that's what I understand from it.

[ChuckOne]

when you update, you just dump the old nxt_db directory into the nxt_db in the unzip directory of the new version, and the blockchain won't be downloaded -just as with before, when you could just dump the blocks.nrs and transactions.nrs into the new version.
only then it would crash very often, and now with sql it hopefully won't.

At least that's what I understand from it.

Well, I see. I don't think we were talking about the 'manual performance of upgrading' but the runtime performance, though.

But, you are right. That's the idea of having a database which is able to handle transactions, rollbacks, caching, indexing etc. at once. Much better than inventing your own serialization format. +1

[mcjavar]

What does this mean?


[2014-02-14 10:39:40.346] DEBUG: Will pop block 5073332198957728923 at height 66148
[2014-02-14 10:39:40.347] DEBUG: Will pop block 8348856438008341233 at height 66147
[2014-02-14 10:39:40.348] DEBUG: Reversal of alias assignment not supported
[2014-02-14 10:39:40.348] DEBUG: Popping off last block not possible, will do a rescan
[2014-02-14 10:39:40.349] Re-scanning blockchain...
[2014-02-14 10:39:54.734] ...Done
[2014-02-14 10:39:54.737] DEBUG: Generate block failed: Previous block id doesn't match

This is all normal, works as intended. It is telling you exactly what is happening - popping off a block, doing a rescan because alias assignment cannot be simply undone in a pop-off. The block generation attempt failed because in the meantime another block arrived and was accepted.

Alias assignment being undone? I didn´t touch the client when this message came.

[Come-from-Beyond]

Not, if the runtime for calculating a sig is dependent on the number of bits of the payload.

It is a common misconception that basic operations are in O(1), but that's wrong. Even addition and multiplication of larger numbers take longer than of smaller numbers. The same hodls for sig function.

I like the conceptual idea of having set-based transactions because set-based thinking is one of the principle of modern computer science.

What I was trying to explain to you was that you should not make not unproven statements.
Show me the runtime complexity of the sig function in terms of payload length and we'll see.

NRS signs SHA256 of a message.

1 signature takes 100 times more CPU ticks than SHA256(32_random_bytes). Signing of a transaction that is 100 times longer ~ 2 ordinary signatures.

Not sure, I got it.

The runtime complexity is still O(n)? But the factory in between is 100? (n = number of bits)

Complexity of signing is O(1).

[jl777]

Question: Is it possible to re-use the nxt_db directory when upgrading from 0.7.4 to 0.7.5  without downloading the whole blockchain again?

Yes, it is designed to be possible to upgrade without having to delete the nxt_db directory, that's the reason I bother with applying those SQL statements.

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

Does this mean that we are actually generating checkpoint files on all the nodes all the time? If so, how much work would it be to have newly installed nodes query for the most recent db files and start with that, instead of redownloading the entire blockchain. Of course, must be peer verified checksums, etc.

How fast does the DB grow at 1000TPS?

[ChuckOne]

Not, if the runtime for calculating a sig is dependent on the number of bits of the payload.

It is a common misconception that basic operations are in O(1), but that's wrong. Even addition and multiplication of larger numbers take longer than of smaller numbers. The same hodls for sig function.

I like the conceptual idea of having set-based transactions because set-based thinking is one of the principle of modern computer science.

What I was trying to explain to you was that you should not make not unproven statements.
Show me the runtime complexity of the sig function in terms of payload length and we'll see.

NRS signs SHA256 of a message.

1 signature takes 100 times more CPU ticks than SHA256(32_random_bytes). Signing of a transaction that is 100 times longer ~ 2 ordinary signatures.

Not sure, I got it.

The runtime complexity is still O(n)? But the factory in between is 100? (n = number of bits)

Complexity of signing is O(1).

That is plain wrong. The more bits you have to sign the longer signing takes. The question is: how long in terms of the input length.

[ChuckOne]

Question: Is it possible to re-use the nxt_db directory when upgrading from 0.7.4 to 0.7.5  without downloading the whole blockchain again?

Yes, it is designed to be possible to upgrade without having to delete the nxt_db directory, that's the reason I bother with applying those SQL statements.

If too slow for Raspberries, do whichever is faster, upgrade or download from scratch.

Did I manage to improve the Raspberry performance with the last release?

Does this mean that we are actually generating checkpoint files on all the nodes all the time? If so, how much work would it be to have newly installed nodes query for the most recent db files and start with that, instead of redownloading the entire blockchain. Of course, must be peer verified checksums, etc.

How fast does the DB grow at 1000TPS?

du says: 257480 for current nxt_db folder