Schema dumping support for PostgreSQL interval type

Closes #27979

4 files changed, 12 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 8de8c05988..e0528c1df6 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -1070,7 +1070,7 @@ module ActiveRecord
               raise ArgumentError, "Error adding decimal column: precision cannot be empty if scale is specified"
             end
 
-          elsif [:datetime, :time].include?(type) && precision ||= native[:precision]
+          elsif [:datetime, :time, :interval].include?(type) && precision ||= native[:precision]
             if (0..6) === precision
               column_type_sql << "(#{precision})"
             else
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/specialized_string.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/specialized_string.rb
index 2d2fede4e8..564e82a4ac 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/specialized_string.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/specialized_string.rb
@@ -5,8 +5,9 @@ module ActiveRecord
         class SpecializedString < Type::String # :nodoc:
           attr_reader :type
 
-          def initialize(type)
+          def initialize(type, **options)
             @type = type
+            super(options)
           end
         end
       end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
index 7491fb716e..372958b9be 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_definitions.rb
@@ -88,6 +88,10 @@ module ActiveRecord
           args.each { |name| column(name, :inet, options) }
         end
 
+        def interval(*args, **options)
+          args.each { |name| column(name, :interval, options) }
+        end
+
         def int4range(*args, **options)
           args.each { |name| column(name, :int4range, options) }
         end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 203566c91b..89d595eef5 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -109,6 +109,7 @@ module ActiveRecord
         bit:         { name: "bit" },
         bit_varying: { name: "bit varying" },
         money:       { name: "money" },
+        interval:    { name: "interval" },
       }
 
       OID = PostgreSQL::OID #:nodoc:
@@ -486,8 +487,10 @@ module ActiveRecord
           m.register_type "polygon", OID::SpecializedString.new(:polygon)
           m.register_type "circle", OID::SpecializedString.new(:circle)
 
-          # FIXME: why are we keeping these types as strings?
-          m.alias_type "interval", "varchar"
+          m.register_type "interval" do |_, _, sql_type|
+            precision = extract_precision(sql_type)
+            OID::SpecializedString.new(:interval, precision: precision)
+          end
 
           register_class_with_precision m, "time", Type::Time
           register_class_with_precision m, "timestamp", OID::DateTime