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. 14. The one or more computer-readable storage media as recited in claim 12 , the acts further comprising, prior to the storing, further filtering the filtered log files based on the expected values or variances of the relevancy between the filtered log files and the search request to filter out a log file having a respective expected value or variance less than or equal to a predefined threshold, wherein the storing comprises: storing the search request and the identifiers of the filtered log files that are further filtered based on the expected values or variances of the relevancy as the keys into the search data structure; and storing the expected values of the relevancy between the search request and the filtered log files that are further filtered based on the expected values or variances of the relevancy as respective values into the search data structure.