I do realize this is an old post, however, I had the same issue of slight fluctuations in search results. During the course of examining this issue, I stumbled upon this yet unanswered question. In my search query, I use the perc() function. Its documentation says the following: The perc and upperperc functions give approximate values for the integer percentile requested. The approximation algorithm that is used, which is based on dynamic compression of a radix tree, provides a strict bound of the actual value for any percentile. This means, sometimes it might be perc50.3, in the next run perc49.6, etc. In my case, this was the cause for the fluctuations I observed. Once I swapped it for a function like avg(), search results were steady.
... View more