3 files changed, 47 insertions, 1 deletions
diff --git a/lib/gitlab/database/migrations/observation.rb b/lib/gitlab/database/migrations/observation.rb
index 54eedec3c7b..a494c357950 100644
--- a/lib/gitlab/database/migrations/observation.rb
+++ b/lib/gitlab/database/migrations/observation.rb
@@ -1,3 +1,4 @@
+# rubocop:disable Naming/FileName
 # frozen_string_literal: true
 
 module Gitlab
@@ -14,3 +15,5 @@ module Gitlab
     end
   end
 end
+
+# rubocop:enable Naming/FileName
diff --git a/lib/gitlab/database/migrations/observers.rb b/lib/gitlab/database/migrations/observers.rb
index 140b3feed64..b890e62c2d0 100644
--- a/lib/gitlab/database/migrations/observers.rb
+++ b/lib/gitlab/database/migrations/observers.rb
@@ -9,7 +9,8 @@ module Gitlab
             TotalDatabaseSizeChange,
             QueryStatistics,
             QueryLog,
-            QueryDetails
+            QueryDetails,
+            TransactionDuration
           ]
         end
       end
diff --git a/lib/gitlab/database/migrations/observers/transaction_duration.rb b/lib/gitlab/database/migrations/observers/transaction_duration.rb
new file mode 100644
index 00000000000..a96b94334cf
--- /dev/null
+++ b/lib/gitlab/database/migrations/observers/transaction_duration.rb
@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Database
+    module Migrations
+      module Observers
+        class TransactionDuration < MigrationObserver
+          def before
+            file_path = File.join(output_dir, "#{observation.version}_#{observation.name}-transaction-duration.json")
+            @file = File.open(file_path, 'wb')
+            @writer = Oj::StreamWriter.new(@file, {})
+            @writer.push_array
+            @subscriber = ActiveSupport::Notifications.subscribe('transaction.active_record') do |*args|
+              record_sql_event(*args)
+            end
+          end
+
+          def after
+            ActiveSupport::Notifications.unsubscribe(@subscriber)
+            @writer.pop_all
+            @writer.flush
+            @file.close
+          end
+
+          def record
+            # no-op
+          end
+
+          def record_sql_event(_name, started, finished, _unique_id, payload)
+            return if payload[:transaction_type] == :fake_transaction
+
+            @writer.push_value({
+                                 start_time: started.iso8601(6),
+                                 end_time: finished.iso8601(6),
+                                 transaction_type: payload[:transaction_type]
+                               })
+          end
+        end
+      end
+    end
+  end
+end