feat(schema): implement schema-diff support and DataType refactoring for PostgreSQL backend

changelog.d/46.added.md

@@ -0,0 +1 @@
+Added PostgreSQL-specific DataType subclasses and schema-diff support with `PostgresSchemaDiffer` for accurate schema introspection and column comparison.

src/rhosocial/activerecord/backend/impl/postgres/__init__.py

@@ -23,6 +23,55 @@
 from .dialect import PostgresDialect
 from .transaction import PostgresTransactionManager, AsyncPostgresTransactionManager
 from .types import PostgresEnumType
+from .expression.types import (
+    PostgresBigSerialType,
+    PostgresBitType,
+    PostgresBoxType,
+    PostgresByteaType,
+    PostgresCIDType,
+    PostgresCircleType,
+    PostgresDateMultirangeType,
+    PostgresDateRangeType,
+    PostgresGeographyType,
+    PostgresGeometryType,
+    PostgresHstoreType,
+    PostgresInetType,
+    PostgresInt4MultirangeType,
+    PostgresInt4RangeType,
+    PostgresInt8MultirangeType,
+    PostgresInt8RangeType,
+    PostgresJsonPathType,
+    PostgresLineSegmentType,
+    PostgresLineType,
+    PostgresMacAddr8Type,
+    PostgresMacAddrType,
+    PostgresMoneyType,
+    PostgresNumMultirangeType,
+    PostgresNumRangeType,
+    PostgresOIDType,
+    PostgresPathType,
+    PostgresPgLSNType,
+    PostgresPointType,
+    PostgresPolygonType,
+    PostgresRegClassType,
+    PostgresRegTypeType,
+    PostgresSerialType,
+    PostgresSmallSerialType,
+    PostgresTIDType,
+    PostgresTSQueryType,
+    PostgresTSVectorType,
+    PostgresTsMultirangeType,
+    PostgresTsRangeType,
+    PostgresTsTzMultirangeType,
+    PostgresTsTzRangeType,
+    PostgresUUIDType,
+    PostgresVarBitType,
+    PostgresVectorType,
+    PostgresXID8Type,
+    PostgresXIDType,
+    PostgresXMLType,
+    PostgresCidrType,
+)
 from .explain import PostgresExplainResult, PostgresExplainPlanLine
 from .expression.ddl import (
     PostgresCreateEnumTypeExpression,
@@ -505,4 +554,52 @@
     # hstore functions - Subscript
     "hstore_subscript_get",
     "hstore_subscript_set",
+    # PostgreSQL DataType subclasses for DDL
+    "PostgresBigSerialType",
+    "PostgresBitType",
+    "PostgresBoxType",
+    "PostgresByteaType",
+    "PostgresCIDType",
+    "PostgresCircleType",
+    "PostgresDateMultirangeType",
+    "PostgresDateRangeType",
+    "PostgresGeographyType",
+    "PostgresGeometryType",
+    "PostgresHstoreType",
+    "PostgresInetType",
+    "PostgresInt4MultirangeType",
+    "PostgresInt4RangeType",
+    "PostgresInt8MultirangeType",
+    "PostgresInt8RangeType",
+    "PostgresJsonPathType",
+    "PostgresLineSegmentType",
+    "PostgresLineType",
+    "PostgresMacAddr8Type",
+    "PostgresMacAddrType",
+    "PostgresMoneyType",
+    "PostgresNumMultirangeType",
+    "PostgresNumRangeType",
+    "PostgresOIDType",
+    "PostgresPathType",
+    "PostgresPgLSNType",
+    "PostgresPointType",
+    "PostgresPolygonType",
+    "PostgresRegClassType",
+    "PostgresRegTypeType",
+    "PostgresSerialType",
+    "PostgresSmallSerialType",
+    "PostgresTIDType",
+    "PostgresTSQueryType",
+    "PostgresTSVectorType",
+    "PostgresTsMultirangeType",
+    "PostgresTsRangeType",
+    "PostgresTsTzMultirangeType",
+    "PostgresTsTzRangeType",
+    "PostgresUUIDType",
+    "PostgresVarBitType",
+    "PostgresVectorType",
+    "PostgresXID8Type",
+    "PostgresXIDType",
+    "PostgresXMLType",
+    "PostgresCidrType",
 ]

src/rhosocial/activerecord/backend/impl/postgres/dialect.py

@@ -90,6 +90,7 @@
     IntrospectionSupport,
     TransactionControlSupport,
     SQLFunctionSupport,
+    DDLTypeSupport,
 )
 from .mixins import (
     PostgresExtensionMixin,
@@ -169,6 +170,7 @@
     PostgresRangeTypeMixin,
     PostgresJSONBEnhancedMixin,
     PostgresArrayEnhancedMixin,
+    PostgresTypeFormatSupportMixin,
     # DDL/DML operation mixins (new)
     PostgresExtendedStatisticsMixin,
     PostgresStoredProcedureMixin,
@@ -400,6 +402,7 @@ class PostgresDialect(
     PostgresFullTextSearchMixin,
     PostgresRangeTypeMixin,
     PostgresArrayEnhancedMixin,
+    PostgresTypeFormatSupportMixin,
     # DDL/DML operation mixins (new)
     PostgresExtendedStatisticsMixin,
     PostgresStoredProcedureMixin,
@@ -524,6 +527,8 @@ class PostgresDialect(
     PostgresRangeTypeSupport,
     PostgresJSONBEnhancedSupport,
     PostgresArrayEnhancedSupport,
+    # DataType Support Protocol
+    DDLTypeSupport,
     # New feature protocols
     PostgresParallelQuerySupport,
     PostgresStoredProcedureSupport,

src/rhosocial/activerecord/backend/impl/postgres/examples/conftest.py

@@ -416,4 +416,46 @@
         'max_version': '18',
         'note': 'Requires superuser or pg_read_server_files role; only available in PG15+ docker images',
     },
+    'schema_diff/table_changes.py': {
+        'title': 'Schema Diff — Table Add/Remove',
+        'dialect_protocols': [],
+        'priority': 10,
+        'min_version': '9',
+        'max_version': '18',
+    },
+    'schema_diff/column_order_irrelevant.py': {
+        'title': 'Schema Diff — Column Order Is Ignored',
+        'dialect_protocols': [],
+        'priority': 10,
+        'min_version': '9',
+        'max_version': '18',
+    },
+    'schema_diff/postgres10_identity.py': {
+        'title': 'Schema Diff — PG9 SERIAL vs PG10+ IDENTITY',
+        'dialect_protocols': [],
+        'priority': 10,
+        'min_version': '9',
+        'max_version': '18',
+    },
+    'schema_diff/array_type_diff.py': {
+        'title': 'Schema Diff — Array Type Dimension Changes',
+        'dialect_protocols': [],
+        'priority': 10,
+        'min_version': '9',
+        'max_version': '18',
+    },
+    'schema_diff/index_type_diff.py': {
+        'title': 'Schema Diff — PostgreSQL Index Type Switches',
+        'dialect_protocols': [],
+        'priority': 10,
+        'min_version': '9',
+        'max_version': '18',
+    },
+    'schema_diff/serialization_roundtrip.py': {
+        'title': 'Schema Diff — Snapshot Serialization Roundtrip',
+        'dialect_protocols': [],
+        'priority': 10,
+        'min_version': '9',
+        'max_version': '18',
+    },
 }

src/rhosocial/activerecord/backend/impl/postgres/examples/ddl/alter_table.py

@@ -38,7 +38,7 @@
 
 drop_table = DropTableExpression(
     dialect=dialect,
-    table_name='users',
+    table='users',
     if_exists=True,
     cascade=True,
 )
@@ -47,7 +47,7 @@
 
 create_table = CreateTableExpression(
     dialect=dialect,
-    table_name='users',
+    table='users',
     columns=[
         ColumnDefinition(
             'id',
@@ -148,13 +148,23 @@
 print("Column renamed successfully")
 
 # Verify table structure
-options = ExecutionOptions(stmt_type=StatementType.DQL)
-result = backend.execute(
-    "SELECT column_name, data_type, is_nullable "
-    "FROM information_schema.columns "
-    "WHERE table_name = 'users' ORDER BY ordinal_position",
-    options=options
+from rhosocial.activerecord.backend.expression import QueryExpression, TableExpression
+from rhosocial.activerecord.backend.expression.core import WildcardExpression, Column
+from rhosocial.activerecord.backend.expression.query_parts import OrderByClause
+
+verify_expr = QueryExpression(
+    dialect=dialect,
+    select=[
+        Column(dialect, 'column_name'),
+        Column(dialect, 'data_type'),
+        Column(dialect, 'is_nullable'),
+    ],
+    from_=TableExpression(dialect, 'columns', schema_name='information_schema'),
+    where=Column(dialect, 'table_name') == Literal(dialect, 'users'),
+    order_by=OrderByClause(dialect, [Column(dialect, 'ordinal_position')]),
 )
+options = ExecutionOptions(stmt_type=StatementType.DQL)
+result = backend.execute(*verify_expr.to_sql(), options=options)
 print("Table structure after alterations:")
 for row in result.data or []:
     print(f" {row}")

src/rhosocial/activerecord/backend/impl/postgres/examples/ddl/create_index.py

@@ -33,7 +33,7 @@
 
 drop_table = DropTableExpression(
     dialect=dialect,
-    table_name='products',
+    table='products',
     if_exists=True,
     cascade=True,
 )
@@ -42,7 +42,7 @@
 
 create_table = CreateTableExpression(
     dialect=dialect,
-    table_name='products',
+    table='products',
     columns=[
         ColumnDefinition(
             'id',
@@ -83,11 +83,17 @@
 print("Index created: idx_category_price")
 
 # Verify index creation
-options = ExecutionOptions(stmt_type=StatementType.DQL)
-verify_result = backend.execute(
-    "SELECT indexname FROM pg_indexes WHERE indexname = 'idx_category_price'",
-    options=options
+from rhosocial.activerecord.backend.expression import QueryExpression, TableExpression
+from rhosocial.activerecord.backend.expression.core import Column, Literal
+
+verify_expr = QueryExpression(
+    dialect=dialect,
+    select=[Column(dialect, 'indexname')],
+    from_=TableExpression(dialect, 'pg_indexes'),
+    where=Column(dialect, 'indexname') == Literal(dialect, 'idx_category_price'),
 )
+options = ExecutionOptions(stmt_type=StatementType.DQL)
+verify_result = backend.execute(*verify_expr.to_sql(), options=options)
 print(f"Index info: {verify_result.data}")
 
 # ============================================================