Merge pull request rails#49592 from fatkodima/pg-table-name-length-back-to-63

Return back maximum allowed PostgreSQL table name to 63 characters

Author: rafaelfranca

activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb

@@ -385,11 +385,18 @@ def rename_table(table_name, new_name, **options)
           execute "ALTER TABLE #{quote_table_name(table_name)} RENAME TO #{quote_table_name(new_name)}"
           pk, seq = pk_and_sequence_for(new_name)
           if pk
-            idx = "#{table_name}_pkey"
-            new_idx = "#{new_name}_pkey"
+            # PostgreSQL automatically creates an index for PRIMARY KEY with name consisting of
+            # truncated table name and "_pkey" suffix fitting into max_identifier_length number of characters.
+            max_pkey_prefix = max_identifier_length - "_pkey".size
+            idx = "#{table_name[0, max_pkey_prefix]}_pkey"
+            new_idx = "#{new_name[0, max_pkey_prefix]}_pkey"
             execute "ALTER INDEX #{quote_table_name(idx)} RENAME TO #{quote_table_name(new_idx)}"
-            if seq && seq.identifier == "#{table_name}_#{pk}_seq"
-              new_seq = "#{new_name}_#{pk}_seq"
+
+            # PostgreSQL automatically creates a sequence for PRIMARY KEY with name consisting of
+            # truncated table name and "#{primary_key}_seq" suffix fitting into max_identifier_length number of characters.
+            max_seq_prefix = max_identifier_length - "_#{pk}_seq".size
+            if seq && seq.identifier == "#{table_name[0, max_seq_prefix]}_#{pk}_seq"
+              new_seq = "#{new_name[0, max_seq_prefix]}_#{pk}_seq"
               execute "ALTER TABLE #{seq.quoted} RENAME TO #{quote_table_name(new_seq)}"
             end
           end

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -605,14 +605,6 @@ def max_identifier_length
         @max_identifier_length ||= query_value("SHOW max_identifier_length", "SCHEMA").to_i
       end
 
-      # Returns the maximum length of a table name.
-      def table_name_length
-        # PostgreSQL automatically creates an index for PRIMARY KEY with name consisting of
-        # truncated table name and "_pkey" suffix fitting into max_identifier_length number of characters.
-        # We allow smaller table names to be able to correctly rename this index when renaming the table.
-        max_identifier_length - "_pkey".length
-      end
-
       # Set the authorized user for this session
       def session_auth=(user)
         clear_cache!

activerecord/test/cases/migration/compatibility_test.rb

@@ -570,6 +570,7 @@ def change
         assert connection.table_exists?(:more_testings)
       ensure
         connection.drop_table(:more_testings) rescue nil
+        connection.drop_table(:new_more_testings) rescue nil
       end
 
       def test_change_column_null_with_non_boolean_arguments_raises_in_a_migration