How to extract Json in AppInsights Analytics Query

Hi,

This seems to be an issue of data types.

If your customDimensions field had been a String, the extractjson method you used would have worked well. For example, see this query.

However, your customDimensions field is of type dynamic, so you should instead use the parsejson method as shown here. In your case it should be:

... | extend duration = customDimensions["1"]

As for the text search, a more efficient solution would be something like this:

... | where customDimensions["{OriginalFormat}"] contains "Time taken to process validation message with operation Id"

HTH,

Noa