Fix dumping declaratively partitioned tables in PostgreSQL

Author: fatkodima

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

@@ -39,6 +39,17 @@ def schemas(stream)
  end
  end
 
+ def table(table, stream)
+ super
+
+ partition_bound_definition = @connection.table_partition_bound_definition(table)
+ if partition_bound_definition
+ partition_table = @connection.inherited_table_names(table).first
+
+ stream.puts " execute \"ALTER TABLE ONLY #{partition_table} ATTACH PARTITION #{table} #{partition_bound_definition}\""
+ end
+ end
+
  def exclusion_constraints_in_create(table, stream)
  if (exclusion_constraints = @connection.exclusion_constraints(table)).any?
  exclusion_constraint_statements = exclusion_constraints.map do |exclusion_constraint|

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

@@ -162,11 +162,14 @@ def table_options(table_name) # :nodoc:
 
  options[:comment] = comment if comment
 
+ partition_bound_definition = table_partition_bound_definition(table_name)
  inherited_table_names = inherited_table_names(table_name).presence
 
- options[:options] = "INHERITS (#{inherited_table_names.join(", ")})" if inherited_table_names
-
- if !options[:options] && supports_native_partitioning?
+ # Can't use :options for declarative partitioning. Partition will be attached
+ # via a separate 'ALTER TABLE ... ATTACH PARTITION ...' call.
+ if inherited_table_names && !partition_bound_definition
+ options[:options] = "INHERITS (#{inherited_table_names.join(", ")})"
+ elsif supports_native_partitioning?
  partition_definition = table_partition_definition(table_name)
 
  options[:options] = "PARTITION BY #{partition_definition}" if partition_definition
@@ -190,7 +193,7 @@ def table_comment(table_name) # :nodoc:
  end
  end
 
- # Returns the partition definition of a given table
+ # Returns the partitioned table definition of a given table
  def table_partition_definition(table_name) # :nodoc:
  scope = quoted_scope(table_name, type: "BASE TABLE")
 
@@ -220,6 +223,21 @@ def inherited_table_names(table_name) # :nodoc:
  SQL
  end
 
+ # Returns the partition definition of a given table
+ def table_partition_bound_definition(table_name) # :nodoc:
+ scope = quoted_scope(table_name, type: "BASE TABLE")
+
+ query_value(<<~SQL, "SCHEMA")
+ SELECT pg_catalog.pg_get_expr(c.relpartbound, c.oid)
+ FROM pg_catalog.pg_class c
+ LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
+ WHERE c.relname = #{scope[:name]}
+ AND c.relkind IN (#{scope[:type]})
+ AND n.nspname = #{scope[:schema]}
+ AND c.relispartition
+ SQL
+ end
+
  # Returns the current database name.
  def current_database
  query_value("SELECT current_database()", "SCHEMA")

activerecord/test/cases/adapters/postgresql/schema_test.rb

@@ -895,9 +895,14 @@ def test_list_partition_options_is_dumped
  t.string :kind
  end
 
- output = dump_table_schema "trains"
+ @connection.create_table "trains_a", id: false, options: "PARTITION OF trains FOR VALUES IN ('a')"
+ @connection.create_table "trains_b", id: false, options: "PARTITION OF trains FOR VALUES IN ('b')"
+
+ output = dump_table_schema "trains", "trains_a", "trains_b"
 
  assert_match("options: \"#{options}\"", output)
+ assert_match(/execute "ALTER TABLE ONLY trains ATTACH PARTITION trains_a FOR VALUES IN \('a'\)"/, output)
+ assert_match(/execute "ALTER TABLE ONLY trains ATTACH PARTITION trains_b FOR VALUES IN \('b'\)"/, output)
  end
 
  def test_range_partition_options_is_dumped