Elasticsearch query by the same body at the same time ,but total is different


i can't believe what i saw,but it happend, our elasticsearch version 1.5.2,i'm updating source and adding a field by python code,and observe the run , the total change a lot , sometime is 1888282 sometime is 2095010 and sometime is 1932892
"filter": {
"exists": {
"field": "why"

(system) #2