12. One or more storage media storing computer-executable instructions that, when executed by one or more processors, cause the one or more processors to perform acts comprising: obtaining exposed log files from a log system; computing Bayesian posterior probabilities for relevancy between the log files and a search request; computing expected values of the relevancy between the log files and the search request; filtering the log files based at least in part on the expected values or variances of the relevancy between the 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; after filtering the log files, 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 relevant log files according to a descending order of the found expected values.
13. The one or more storage media as recited in claim 12 , wherein prior to computing the Bayesian posterior probabilities, the method further comprises filtering the exposed log files based on global parameters to filter out a log file having a respective global parameter less than a predetermined threshold, wherein computing the Bayesian posterior probabilities comprises computing Bayesian posterior probabilities for relevancy between the search request and log files that remain after the filtering based on the global parameters.