FIX: Add time retention limit to search logs

3 years is a very conservative limit that allows for a very wide buffer
for year-over-year analysis. The max is set to 5 years because that is
the policy listed for logging in hosted Discourse.

app/models/search_log.rb

@@ -134,6 +134,7 @@ class SearchLog < ActiveRecord::Base
     if search_id.present?
       SearchLog.where('id < ?', search_id[0]).delete_all
     end
+    SearchLog.where('created_at < TIMESTAMP ?', SiteSetting.search_query_log_max_retention_days.days.ago).delete_all
   end
 end
 

config/locales/server.en.yml

@@ -1069,6 +1069,7 @@ en:
     search_recent_posts_size: "How many recent posts to keep in the index"
     log_search_queries: "Log search queries performed by users"
     search_query_log_max_size: "Maximum amount of search queries to keep"
+    search_query_log_max_retention_days: "Maximum amount of time to keep search queries, in days. Default is 3 years (1095 days)."
     allow_uncategorized_topics: "Allow topics to be created without a category. WARNING: If there are any uncategorized topics, you must recategorize them before turning this off."
     allow_duplicate_topic_titles: "Allow topics with identical, duplicate titles."
     unique_posts_mins: "How many minutes before a user can make a post with the same content again"

config/site_settings.yml

@@ -1362,6 +1362,9 @@ search:
   search_query_log_max_size:
     default: 1000000
     max: 1000000
+  search_query_log_max_retention_days:
+    default: 1095 # 3 years
+    max: 1825 # 5 years
 
 uncategorized:
   version_checks: