Use PG to detect the column

In the previous commit we're using a wildcard to select all columns,
now by using PGs information_schema we query if the column exits.

lib/gitlab_monitor/database/ci_builds.rb

@@ -27,12 +27,39 @@ module GitLab
           "    AND ci_builds.status = 'running' " \
           "    AND ci_builds.updated_at < NOW() - INTERVAL '1 hour'".freeze
 
-        PER_RUNNER_QUERY =
+        PER_RUNNER_QUERY_EE =
           <<~SQL.freeze
             SELECT
               ci_builds.runner_id,
               ci_runners.is_shared,
-              projects.*,
+              projects.mirror,
+              projects.pending_delete,
+              projects.mirror_trigger_builds,
+              ci_pipelines.pipeline_schedule_id,
+              ci_builds.trigger_request_id,
+              COUNT(*) AS count
+            FROM ci_builds
+            JOIN ci_runners
+              ON ci_runners.id = ci_builds.runner_id
+            JOIN projects
+              ON projects.id = ci_builds.project_id
+            JOIN ci_pipelines
+              ON ci_pipelines.id = ci_builds.commit_id
+            WHERE ci_builds.type = 'Ci::Build'
+              AND ci_builds.status = 'running'
+            GROUP BY
+              ci_builds.runner_id,
+              ci_runners.is_shared,
+              ci_pipelines.pipeline_schedule_id,
+              ci_builds.trigger_request_id
+          SQL
+
+        PER_RUNNER_QUERY_CE =
+          <<~SQL.freeze
+            SELECT
+              ci_builds.runner_id,
+              ci_runners.is_shared,
+              projects.pending_delete,
               ci_pipelines.pipeline_schedule_id,
               ci_builds.trigger_request_id,
               COUNT(*) AS count
@@ -59,7 +86,9 @@ module GitLab
           results.merge!(get_builds(BUILDS_QUERY))
 
           results[:stale_builds] = get_general(STALE_BUILDS_QUERY)
-          results[:per_runner] = get_per_runner(PER_RUNNER_QUERY)
+
+          query = mirror_column? ? PER_RUNNER_QUERY_EE : PER_RUNNER_QUERY_CE
+          results[:per_runner] = get_per_runner(query)
           results
         end
 
@@ -115,6 +144,20 @@ module GitLab
         rescue PG::UndefinedTable, PG::UndefinedColumn
           results
         end
+
+        def mirror_column?
+          @mirror_column ||=
+            begin
+              connection.exec(
+                <<~SQL
+                SELECT EXISTS
+                  (SELECT 1 FROM information_schema.columns WHERE table_name='projects' AND column_name='mirror')
+              SQL
+              )[0]["exists"] == "t"
+            rescue PG::UndefinedColumn
+              false
+            end
+        end
       end
 
       # The prober which is called when gathering metrics

spec/database/ci_builds_spec.rb

@@ -6,14 +6,16 @@ describe GitLab::Monitor::Database do
   let(:builds_query) { "SELECT BUILDS" }
   let(:stale_builds_query) { "SELECT NOT UPDATED RUNNING" }
   let(:per_runner_query) { "SELECT ALL RUNNING PER RUNNER" }
+  let(:mirror_column_query) { "SELECT EXISTS \n  (SELECT 1 FROM information_schema.columns WHERE table_name='projects' AND column_name='mirror')\n" }
   let(:connection) { double("connection") }
 
   before do
     stub_const("GitLab::Monitor::Database::CiBuildsCollector::BUILDS_QUERY", builds_query)
     stub_const("GitLab::Monitor::Database::CiBuildsCollector::STALE_BUILDS_QUERY", stale_builds_query)
-    stub_const("GitLab::Monitor::Database::CiBuildsCollector::PER_RUNNER_QUERY", per_runner_query)
+    stub_const("GitLab::Monitor::Database::CiBuildsCollector::PER_RUNNER_QUERY_EE", per_runner_query)
 
     allow_any_instance_of(GitLab::Monitor::Database::CiBuildsCollector).to receive(:connection).and_return(connection)
+    allow_any_instance_of(GitLab::Monitor::Database::CiBuildsCollector).to receive(:mirror_column?).and_return(true)
 
     allow(connection).to receive(:exec).with(builds_query)
       .and_return([{ "shared_runners_enabled" => "f", "status" => "created", "namespace_id" => "1", "count" => 10 },