Number of rows in QueryPropertyHistory

[preddy-2]

Hello All,

I have a confusion in, how many number of rows valuestream querypropertyhistory returns?

I have a device with 3 properties (i,j,k) and I am updating these values every minute in timer event.

In the mashup, I bound thing's  'querypropertyhistory' to the Grid. And I am refreshing 'querypropertyhistory' every minute.

Result is, number of rows is totally unpredicted way...

The distance between two time stamps is 1 minute as my timer event is for every minute.

But I wonder why for few time stamps two entries and for other time stamps, only one entry is there.  Can anyone has better explanation?

Thank you.

With B/R,

Praveen.B

[ttielebein]

Hello,

This is the grid as it appears in a mashup, right? When you query the value stream directly on the Thing, does it display like this also? It is possible that some data is not being written to the value stream in that case. Otherwise, there may be something wrong with the way it is displaying in the grid.

Thanks!

Tori

[preddy-2]

Hi Tori,

Yes...that is the grid in mashup. I queried directly thing value stream, that result also same. Below is the screenshot.

Not sure how to understand this.

With B/R,

Praveen.B

[ttielebein]

Ok, so it looks like some data is not being written to the value stream properly. Can you please go to the Application Log and see if there are any error messages?

[preddy-2]

No.I do not see any relevant application log errors also.

With B/R,

Praveen.B

[ttielebein]

How is your value stream set up? Do properties log to it whenever there are changes? Are you sure properties are updating when they are supposed to?

[Aanjan]

Praveen, here's an article on how QueryPropertyHistory works when using multiple properties.

[preddy-2]

Hi Ravi,

Thank you for the reference data.Even with that explanation also,I don't see any case of multiple entries for same time stamp.

In my case, few of the time stamps came twice in the table. How can it be possible?

With B/R,

Praveen.B