[{keyword:"hello",section_name:"talk",category_path:"info",username:["joy","sadness"]},{keyword:"hello joy",section_name:"talk",category_path:"info",username:["joy"]},{keyword:"shoes",section_name:"market",category_path:"sell",username:["joy"]}]

db.collection.find({"keyword":{$regex:"hello|my|name|is|joy"},"section_name":"talk","category_path":"info"})