feat: Support prepend SQL comment for PG instrumentation (#690)

Co-authored-by: Ariel Valentin <arielvalentin@users.noreply.github.com>
Co-authored-by: Kayla Reopelle (she/her) <87386821+kaylareopelle@users.noreply.github.com>

instrumentation/pg/lib/opentelemetry/instrumentation/pg/patches/connection.rb

@@ -112,7 +112,9 @@ def span_attrs(kind, *args)
 
           def extract_operation(sql)
             # From: https://github.com/open-telemetry/opentelemetry-js-contrib/blob/9244a08a8d014afe26b82b91cf86e407c2599d73/plugins/node/opentelemetry-instrumentation-pg/src/utils.ts#L35
-            sql.to_s.split[0].to_s.upcase
+            # Ignores prepend comment
+            comment_regex = %r{\A\/\*.*?\*\/}m
+            sql.to_s.sub(comment_regex, '').split[0].to_s.upcase
           end
 
           def span_name(operation)

instrumentation/pg/test/opentelemetry/instrumentation/pg/instrumentation_test.rb

@@ -177,6 +177,18 @@
       end
     end
 
+    it 'ignores prepend comment to extract operation' do
+      client.query('/* comment */ SELECT 1')
+
+      _(span.name).must_equal 'SELECT postgres'
+      _(span.attributes['db.system']).must_equal 'postgresql'
+      _(span.attributes['db.name']).must_equal 'postgres'
+      _(span.attributes['db.statement']).must_equal '/* comment */ SELECT 1'
+      _(span.attributes['db.operation']).must_equal 'SELECT'
+      _(span.attributes['net.peer.name']).must_equal host.to_s
+      _(span.attributes['net.peer.port']).must_equal port.to_i
+    end
+
     it 'only caches 50 prepared statement names' do
       51.times { |i| client.prepare("foo#{i}", "SELECT $1 AS foo#{i}") }
       client.exec_prepared('foo0', [1])