Hello @prathamesh_h
There is great documentation on rowkey design here: https://hbase.apache.org/book.html#rowkey.design
At a high level, you want to ensure that your rowkeys are as evenly distributed as possible. If you have very few sites and many articles for each site, you may not see great performance.
You can consider ways to break your articles into smaller buckets within each site, and including this in your rowkey.