Getstatistic.jsp caching data server side?

API
#1

I’m currently using /service/r2/getstatistic.jsp to get energy generated in watt hours for a range of dates, or for the current day. However, I’m noticing that if I pass the current date to date from and date to (df and dt), it sometimes caches data for the current day. For instance, I’ll make a request and it gives me statistical data that was valid 20 minutes ago, but not right now.

Is this a bug in the API, or is getstatistic not something I should be using for getting real time data? And if it’s not something that should be used for real time data, I think that there should be a note in the API specification that the server caches statistics and that it’s not real time like getstatus is.

I know this is not client side caching because I tested this on two different computers and get the same result. I also tried passing “Cache-Control: no-store” and “Cache-Control: no-cache” for my headers, but that doesn’t seem to do anything.

#2

For current data you probably should use today’s date for from and tomorrow’s date for to.

#3

I could do that, but that shouldn’t have an affect on the data I get back unless the system I’m requesting a statistic from has data for what my program thinks is tomorrow, which shouldn’t happen unless I get timezones or something wrong, which I know isn’t the problem because I’m using the correct date based on the system’s timezone.

I’ll probably end up using getstatus for this, but I might end up testing your suggestion and if that for some reason makes it stop caching data, I’ll have to decide between the two.

#4

Get Statistic provides summary data and is cached for 2-hours.

The cache is reduced to 15-minutes for donation enabled accounts.

1 Like
#5

Gotcha, that makes sense. I think that should be added to the documentation.

Also, it would be nice if returned data could somehow indicate the last time the data was calculated/cached, but that would probably break someone’s program.

#6

But it is strange that:
https://pvoutput.org/service/r2/getstatistic.jsp?c=1&crdr=0&df=20210317&dt=20210317
provide:
11133,0,11133,11133,11133,1.776,1,20210317,20210317,1.776,20210317,0,0,0,0,0,0,0,0
which is old data but when c=0 it is ok
https://pvoutput.org/service/r2/getstatistic.jsp?c=0&crdr=0&df=20210317&dt=20210317
10696,6847,10696,10696,10696,1.706,1,20210317,20210317,1.706,20210317
Is it expected behaviour ?

#7

If I remember correctly, passing different parameters will result in it recaching/recalculating the data. However, if you request the same parameters again, I think it uses the cached data. So it’s like there are multiple caches depending on what parameters you pass. That’s how I remember it at least, I could be wrong.

I think if you continuously have c=0 it will start to use the cached data. So the first time you request, it will look right, but I think after a little while it will be off.