Syntax to extract a particular key-value from BSON message

Hi,

 

I’m new to q language. My question is

what is the syntax to extract a particular key-value from BSON message?

For instance if I need SourceSystemName from the key value pair in BSON message for all 50k records  how can i extract that?

 

Thanks,

Priya

You can index at depth:

records[;`SourceSystemName]

https://kx.com/blog/kdb-q-insights-parsing-json-files/