Another serious bug in the API...

[JayBee]

I am building a bot that monitors all prices for all runners in all horse races.

Hundreds of times per day the bot will identify an increase in volume traded on a runner through the totalMatched value for the runner and yet there is no increase in size for any price for the traded volume on that runner.

Why is the totalMatched being updated with new volume and yet there is no update in the list of price/size?

Now I am going to be asked by Betfair to provide examples.

I FLATLY REFUSE to do unpaid work for Betfair but I WILL point out to users of the API that the API is riddled with bugs and we are not being paid to debug it.

I pointed out the duplicate runner bug last year and was told that I was imagining things. I provided an example and was told it would be fixed. It has not been fixed to this day. I provided more examples and was told just to keep sending examples. I am not a Betfair developer so I am no longer going to assist Betfair in its debugging but I will be pointing out all the bugs to the people on this forum.

[Mr Magoo]

It'd be a start if Betfair actually replied to some of the messages on this forum and discussed API issues with us.

At the moment, this place just seems to be yet another place for Betfair to ignore us.

[BetfairDeveloperProgram]

Hi JayBee,

Thanks for bringing this to our attention. We are investigating this issue and will provide an update shortly.

Neil

[JayBee]

Hi JayBee,

Thanks for bringing this to our attention. We are investigating this issue and will provide an update shortly.

Neil

Thank you.

I can also add that totalMatched never equals the total of individual size values in traded volume for any runner in any race.

[Betfair Developer Program]

Hi JayBee,

Please can you provide an example relating to the first issue? We can then check if this is due to a specific business rule or something else.

I can also add that totalMatched never equals the total of individual size values in traded volume for any runner in any race

We'll investigate this further as we can see there is a discrepancy in the amounts. This may be due to the way the various matched values are rounded.

Thanks

Neil

[JayBee]

Sorry but as I said in my original post I am not prepared to do this work unpaid.

It would be a simple task for your developers to note on a runner that the totalMatched has increased.

You then loop through the size values for all the volume to see if any of them has increased.

You will find many instances where the totalMatched increases and yet the size values for the previously matched prices does not increase.

If your developers are unable to do this simple task then maybe your manager would like to employ me. I can supply a CV on request.

Hi JayBee,

Please can you provide an example relating to the first issue? We can then check if this is due to a specific business rule or something else.



We'll investigate this further as we can see there is a discrepancy in the amounts. This may be due to the way the various matched values are rounded.

Thanks

Neil

[BetfairDeveloperProgram]

Hi JayBee,

We have attempted to capture instances of this issue but have not been able to see this behaviour while looking at all UK win/place horse markets over a couple of days.

However, there are a couple of possibilities regarding why you may think that this issue may be occurring:

1) Floating point (double) precision artifact:

In the following example you can see that the traded volume seems to have changed and a bot may believe this is the case depending on how it compares doubles. But in fact the traded volume has remained the same (99) and the difference is caused by how floating point numbers work.

Time: 2014-08-19 17:59:53.605
Market Id: 1.115065189
Old:
Runner{selectionId='4980984', tradedLadder={5.7=5.600806632310105, 4.4=4.0, 5.2=5.4, 4.9=6.0, 3.9=10.0, 4.2=6.0, 4.3=3.9997759354694153, 5.6=12.0, 4.0=26.0, 5.5=14.0, 5.3=6.0}, tradedVolume=99.00058256777952}
New: 
Runner{selectionId='4980984', tradedLadder={5.7=5.600022400179202, 4.4=4.0, 5.2=5.4, 4.9=6.0, 3.9=10.0, 4.2=6.0, 4.3=3.9992159937279497, 5.6=12.0, 4.0=26.0, 5.5=14.0, 5.3=6.0}, tradedVolume=98.99923839390715}

If the total traded volume is increasing by more than 1 this would rule out this possibility. Please can you confirm this?

2) Perhaps when you are adding up the sizes on the traded ladder you are not taking into account that a new price point could exist on the ladder with a size that explains the increased total traded volume. You may just be adding up the prices from the previous ladder. Although we would expect that you have accounted for this already.

Without an example demonstrating the issue, the cause is difficult to explain, particularly as we are unable to recreate it.

Kind Regards

Neil