Thanks Vani. Stephen posted this question on behalf of me.  Thanks to both of you. I have verified the attribute Cookies , it is enabled in our data for most of the cases where we are seeing post_visit_high /low are NULL. exclude hit-  our configuration not used it seems- we are seeing either NULL o...

another question If post_visid_high/low are null. Do we consider these records are valid visits ? or not. how do we calculate the no of visits if these are null ?

Thanks Stephen Can you please help to understand which column can express MCID service deployed with grace period activated or not ? or which column I can refer for 'aid' I would like to see the data pattern where post_visid_high/low are NULL.  

I understand that Post_visid_high and Post_visid_low attributes can be used to determine a unique user of the visits. But some cases, we have got NULL values of these attributes. would like to know, how to understand these records.