12. One or more computer-readable storage media storing computer-executable instructions that, when executed by one or more processors, configure the one or more processors to perform acts comprising: obtaining exposed log files from a log system; filtering the exposed log files based on global parameters to filter a log file having a respective global parameter less than a predefined threshold; after filtering the exposed log files, computing Bayesian posterior probabilities for relevancy between the filtered log files and a search request; computing expected values of the relevancy between the filtered log files and the search request; storing the search request and identifiers of the filtered log files as keys and the expected values of the relevancy between the filtered log files and the search request as respective values into a search data structure; in response to receiving a search request submitted by a user, finding expected values of relevancy between the search request submitted by the user and log files that are relevant to the submitted search request from the search data structure; and ordering the found log files according to a descending order of the found expected values.
12. One or more computer-readable storage media storing computer-executable instructions that, when executed by one or more processors, configure the one or more processors to perform acts comprising: obtaining exposed log files from a log system; filtering the exposed log files based on global parameters to filter a log file having a respective global parameter less than a predefined threshold; after filtering the exposed log files, computing Bayesian posterior probabilities for relevancy between the filtered log files and a search request; computing expected values of the relevancy between the filtered log files and the search request; storing the search request and identifiers of the filtered log files as keys and the expected values of the relevancy between the filtered log files and the search request as respective values into a search data structure; in response to receiving a search request submitted by a user, finding expected values of relevancy between the search request submitted by the user and log files that are relevant to the submitted search request from the search data structure; and ordering the found log files according to a descending order of the found expected values. 13. The one or more computer-readable media as recited in claim 12 , wherein the filtering comprises: selecting log files that have been exposed once and have not been clicked from the exposed log files; and filtering, from the selected log files, the log file having the respective global parameter less than the predefined threshold according to a filtering criteria formula β r , d < 1 / E th 1 3 / 1 2 ⁢ E th , wherein β r,d is a global parameter, β ^ r , d = min ⁢ { 1 , 2 ⁢ N r , d N r , d + N ~ r , d } , N r,d is the number of occurrences for a situation when log files located at position r and r+d are clicked and log files located at positions between r and r+d are not clicked in a same click sequence including the selected log files, Ñ r,d is the number of occurrences for a situation when a log file located at position r is clicked, a log file located at position r+d is not clicked and log files located at positions between r and r+d are not clicked in the same click sequence including the selected log files, a value of r is a natural number that is less than or equal to M−1, and a value of d is an integer that is less than or equal to M−r, M representing the total number of log files in the same click sequence including the selected log files, and E th is a predefined threshold value corresponding to an expected value of relevancy between a log file and a search request.