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jholl016 Frequent Visitor
Frequent Visitor

Missing data when querying Log Analytics

When I query my Log Analytics workspace, the returned results are missing "windows" of data at various locations in the results table.  Here is my kusto query in LA:

Event 
| where EventLog == "Talon"
| search EventData contains ":Filename=TafsMtPt:"
| parse RenderedDescription with "Result=" Result ":error=" Error "Smiley Tongueeer=" Peer "Smiley Very Happyirection=" Direction ":Mode=" Mode ":Filename=TafsMtPt:" Filename ":File Size=" FileSize ":Bytes Exchanged=" BytesExchanged ":Transfer Efficiency=" TransferEfficiency "Smiley FrustratedID=" UserSID
| project Computer, Result, Error, Peer, Direction, Mode, Filename, FileSize, BytesExchanged, TransferEfficiency, UserSID, TimeGenerated, EventLevelName
| project-rename EventTime = TimeGenerated, LogType = EventLevelName
| where Filename !contains "-temp." and Filename !contains "desktop.ini" and Filename !contains "~$" and Filename !contains ".tmp" and Filename !endswith "_placeholder_"

When I run this query in the Azure portal, I get complete results, with no missing data.  Visualizing the results in a Log Analytics workspace summary by counting the number of events in hourly bins, you see spikes in the number of events for each weekday.

LA_WorkspaceSummary.png

But when I export the kusto query to M Query for Power BI, the resultant data set is missing a significant amount of data.  Two of the weekday peaks are missing entirely.

PowerBI_Results.png

 

I am using the latest edition of Power BI desktop.  What on earth is going on here?

 

1 ACCEPTED SOLUTION

Accepted Solutions
jholl016 Frequent Visitor
Frequent Visitor

Re: Missing data when querying Log Analytics

I resolved this. My missing data was due to a results table that violated the 64,000,000 bytes maximum enforced by the Log Analytics API.  I will have to re-architect my queries with this limitation in mind.  The Log Analytics API limitations are documented here:

 

https://dev.loganalytics.io/documentation/Using-the-API/Limits

2 REPLIES 2
Community Support Team
Community Support Team

Re: Missing data when querying Log Analytics

Hi @jholl016 ,

 

Based on my test, I cannot reproduce your issue here. I recommend you to create a support ticket for help if you are a pro user.
 
https://powerbi.microsoft.com/en-us/support/

Support Ticket.gif

 



Community Support Team _ Frank
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
jholl016 Frequent Visitor
Frequent Visitor

Re: Missing data when querying Log Analytics

I resolved this. My missing data was due to a results table that violated the 64,000,000 bytes maximum enforced by the Log Analytics API.  I will have to re-architect my queries with this limitation in mind.  The Log Analytics API limitations are documented here:

 

https://dev.loganalytics.io/documentation/Using-the-API/Limits