Merge branch 'improve-mirror-queries' into 'master'

Improve mirror queries

See merge request gitlab-org/gitlab-exporter!111

lib/gitlab_exporter/database/row_count.rb

@@ -12,8 +12,13 @@ module GitLab
       class RowCountCollector < Base
         WHERE_MIRROR_ENABLED = <<~SQL.freeze
           projects.mirror = true
+          AND projects.archived = false
           AND project_mirror_data.retry_count <= 14
-          AND (projects.visibility_level = 20 OR plans.name IN ('early_adopter', 'bronze', 'silver', 'gold'))
+          AND (
+            (projects.visibility_level = 20 AND root_namespaces.visibility_level = 20)
+            OR
+            plans.name IN ('early_adopter', 'bronze', 'silver', 'gold')
+          )
         SQL
 
         MIRROR_QUERY = {