@youssefmrini @erigaud 

I have a similar issue, and I've pretty much tried the solution mentioned above. However, I'm not noticing any changes when I use a temporary table or persist the table.

My main table contains 3.1 terabytes of data with 42 billion records, and the incoming staging table has 7 gigabytes of data with 90 million records. The staging table is also similarly partitioned as the main table, and I can see that almost 90% of the main table has been scanned. 

For Your Information. I am using 15.2 DBR. 

Regards,

Gokul