Drop comments from structure.sql in postgresql

Fixes #28153.

3 files changed, 38 insertions, 3 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index a2566ae5fb..9f42ebd175 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   Remove comments from structure.sql when using postgresql adapter to avoid
+    version-specific parts of the file.
+
+    Fixes #28153.
+
+    *Ari Pollak*
+
 *   Deprecate using `#quoted_id` in quoting.
 
     *Ryuta Kamizono*
diff --git a/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb b/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb
index 5155ced0e2..83b82506d3 100644
--- a/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/postgresql_database_tasks.rb
@@ -1,3 +1,5 @@
+require "tempfile"
+
 module ActiveRecord
   module Tasks # :nodoc:
     class PostgreSQLDatabaseTasks # :nodoc:
@@ -65,6 +67,7 @@ module ActiveRecord
         end
         args << configuration["database"]
         run_cmd("pg_dump", args, "dumping")
+        remove_sql_comments(filename)
         File.open(filename, "a") { |f| f << "SET search_path TO #{connection.schema_search_path};\n\n" }
       end
 
@@ -110,6 +113,18 @@ module ActiveRecord
           msg << "Please check the output above for any errors and make sure that `#{cmd}` is installed in your PATH and has proper permissions.\n\n"
           msg
         end
+
+        def remove_sql_comments(filename)
+          tempfile = Tempfile.open('uncommented_structure.sql')
+          begin
+            File.foreach(filename) do |line|
+              tempfile << line unless line.start_with?('--')
+            end
+          ensure
+            tempfile.close
+          end
+          FileUtils.mv(tempfile.path, filename)
+        end
     end
   end
 end
diff --git a/activerecord/test/cases/tasks/postgresql_rake_test.rb b/activerecord/test/cases/tasks/postgresql_rake_test.rb
index a23100c32a..a28217c2e6 100644
--- a/activerecord/test/cases/tasks/postgresql_rake_test.rb
+++ b/activerecord/test/cases/tasks/postgresql_rake_test.rb
@@ -217,17 +217,21 @@ if current_adapter?(:PostgreSQLAdapter)
 
     class PostgreSQLStructureDumpTest < ActiveRecord::TestCase
       def setup
-        @connection    = stub(structure_dump: true)
+        @connection    = stub(schema_search_path: nil, structure_dump: true)
         @configuration = {
           "adapter"  => "postgresql",
           "database" => "my-app-db"
         }
-        @filename = "awesome-file.sql"
+        @filename = "/tmp/awesome-file.sql"
+        FileUtils.touch(@filename)
 
         ActiveRecord::Base.stubs(:connection).returns(@connection)
         ActiveRecord::Base.stubs(:establish_connection).returns(true)
         Kernel.stubs(:system)
-        File.stubs(:open)
+      end
+
+      def teardown
+        FileUtils.rm_f(@filename)
       end
 
       def test_structure_dump
@@ -236,6 +240,15 @@ if current_adapter?(:PostgreSQLAdapter)
         ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
       end
 
+      def test_structure_dump_comments_removed
+        Kernel.stubs(:system).returns(true)
+        File.write(@filename, "-- comment\n not comment\n")
+
+        ActiveRecord::Tasks::DatabaseTasks.structure_dump(@configuration, @filename)
+
+        assert_equal " not comment\n", File.readlines(@filename).first
+      end
+
       def test_structure_dump_with_extra_flags
         expected_command = ["pg_dump", "-s", "-x", "-O", "-f", @filename, "--noop", "my-app-db"]