Add support for introspecting domain types

changelog.md

@@ -2,6 +2,15 @@
 
 ## [Unreleased]
 
+### Added
+
+- Support for introspecting domain types.
+  ([#380](https://github.com/hasura/ndc-postgres/pull/380))
+
+### Changed
+
+### Fixed
+
 ## [v0.5.1] - 2024-03-21
 
 ### Added

crates/configuration/src/version3/version3.sql

@@ -8,7 +8,7 @@
 -- query with arguments set.
 
 -- DEALLOCATE ALL; -- Or use 'DEALLOCATE configuration' between reloads
--- PREPARE configuration(varchar[], varchar[], jsonb, varchar[]) AS
+-- PREPARE configuration(varchar[], varchar[], varchar[], jsonb, varchar[]) AS
 
 WITH
   -- The overall structure of this query is a CTE (i.e. 'WITH .. SELECT')
@@ -215,12 +215,15 @@ WITH
       -- query execution. If we export them as opaque scalar types, adding
       -- proper support later becomes a breaking change, which we'd like to
       -- avoid.
+      --
+      -- We intentionally do not filter out domain types, see the relation
+      -- `domain_types` below.
       t.typtype NOT IN
       (
         -- Interesting t.typtype 'types of types':
         -- 'b' for base type
-        'c', --for composite type
-        -- 'd' for domain (a predicate-restricted version of a type)
+        'c', -- for composite type
+        -- 'd', for domain (a predicate-restricted version of a type)
         -- 'e' for enum
         'p' -- for pseudo-type (anyelement etc)
         -- 'r' for range
@@ -263,6 +266,36 @@ WITH
         'xid8'
         )
   ),
+  -- Domain types are scalar types that have been adorned with a CHECK
+  -- expression that any instance of the type must satisfy.
+  --
+  -- While the `scalar_types` relation above does pick up on domain types as
+  -- well we also need to keep track of them separately in order to be able to
+  -- infer comparison operators and aggregation functions.
+  --
+  -- Domain types are created using the `CREATE DOMAIN` statement (see
+  -- https://www.postgresql.org/docs/current/sql-createdomain.html).
+  domain_types AS
+  (
+    SELECT
+      t.oid AS type_id,
+      t.typnamespace AS schema_id,
+      t.typname AS type_name,
+      base_type.type_name AS base_type
+    FROM
+      pg_catalog.pg_type AS t
+    INNER JOIN
+      -- Until the schema is made part of our model of types we only consider
+      -- those defined in the public schema.
+      unqualified_schemas_for_types_and_procedures as q
+      ON (t.typnamespace = q.schema_id)
+    INNER JOIN
+      scalar_types
+      AS base_type
+      ON (base_type.type_id = t.typbasetype)
+    WHERE
+      t.typtype = 'd'
+  ),
   array_types AS
   (
     SELECT
@@ -505,6 +538,14 @@ WITH
           ('geometry', 'text'),
           ('text', 'geometry')
         )
+    UNION
+    -- Any domain type may be implicitly cast to its base type, even though these casts
+    -- are not declared in `pg_cast`.
+    SELECT
+      domain_types.type_name as from_type,
+      domain_types.base_type as to_type
+    FROM
+      domain_types
   ),
 
   -- Some comparison operators are not defined explicitly for every type they would be

crates/tests/databases-tests/src/citus/snapshots/databases_tests__citus__schema_tests__schema_test__get_schema.snap

@@ -244,6 +244,52 @@ expression: result
         }
       }
     },
+    "even_number": {
+      "aggregate_functions": {},
+      "comparison_operators": {
+        "_eq": {
+          "type": "equal"
+        },
+        "_gt": {
+          "type": "custom",
+          "argument_type": {
+            "type": "named",
+            "name": "even_number"
+          }
+        },
+        "_gte": {
+          "type": "custom",
+          "argument_type": {
+            "type": "named",
+            "name": "even_number"
+          }
+        },
+        "_in": {
+          "type": "in"
+        },
+        "_lt": {
+          "type": "custom",
+          "argument_type": {
+            "type": "named",
+            "name": "even_number"
+          }
+        },
+        "_lte": {
+          "type": "custom",
+          "argument_type": {
+            "type": "named",
+            "name": "even_number"
+          }
+        },
+        "_neq": {
+          "type": "custom",
+          "argument_type": {
+            "type": "named",
+            "name": "even_number"
+          }
+        }
+      }
+    },
     "float4": {
       "aggregate_functions": {
         "avg": {
@@ -2198,6 +2244,16 @@ expression: result
         }
       }
     },
+    "even_numbers": {
+      "fields": {
+        "the_number": {
+          "type": {
+            "type": "named",
+            "name": "even_number"
+          }
+        }
+      }
+    },
     "insert_album": {
       "fields": {
         "AlbumId": {
@@ -3338,6 +3394,38 @@ expression: result
         }
       }
     },
+    "v1_insert_even_numbers_object": {
+      "fields": {
+        "the_number": {
+          "type": {
+            "type": "named",
+            "name": "even_number"
+          }
+        }
+      }
+    },
+    "v1_insert_even_numbers_response": {
+      "description": "Responses from the 'v1_insert_even_numbers' procedure",
+      "fields": {
+        "affected_rows": {
+          "description": "The number of rows affected by the mutation",
+          "type": {
+            "type": "named",
+            "name": "int4"
+          }
+        },
+        "returning": {
+          "description": "Data from rows affected by the mutation",
+          "type": {
+            "type": "array",
+            "element_type": {
+              "type": "named",
+              "name": "even_numbers"
+            }
+          }
+        }
+      }
+    },
     "value_types": {
       "fields": {
         "bool": {
@@ -3708,6 +3796,13 @@ expression: result
         }
       }
     },
+    {
+      "name": "even_numbers",
+      "arguments": {},
+      "type": "even_numbers",
+      "uniqueness_constraints": {},
+      "foreign_keys": {}
+    },
     {
       "name": "address_identity_function",
       "description": "A native query used to test support for composite types",
@@ -4465,6 +4560,22 @@ expression: result
         "type": "named",
         "name": "v1_insert_Track_response"
       }
+    },
+    {
+      "name": "v1_insert_even_numbers",
+      "description": "Insert into the even_numbers table",
+      "arguments": {
+        "_object": {
+          "type": {
+            "type": "named",
+            "name": "v1_insert_even_numbers_object"
+          }
+        }
+      },
+      "result_type": {
+        "type": "named",
+        "name": "v1_insert_even_numbers_response"
+      }
     }
   ]
 }

crates/tests/databases-tests/src/postgres/snapshots/databases_tests__postgres__configuration_tests__postgres_current_only_configure_v3_initial_configuration_is_unchanged.snap

@@ -823,6 +823,23 @@ expression: default_configuration
         "foreignRelations": {},
         "description": null
       },
+      "even_numbers": {
+        "schemaName": "public",
+        "tableName": "even_numbers",
+        "columns": {
+          "the_number": {
+            "name": "the_number",
+            "type": {
+              "scalarType": "even_number"
+            },
+            "nullable": "nonNullable",
+            "description": null
+          }
+        },
+        "uniquenessConstraints": {},
+        "foreignRelations": {},
+        "description": null
+      },
       "spatial_ref_sys": {
         "schemaName": "public",
         "tableName": "spatial_ref_sys",
@@ -1301,6 +1318,50 @@ expression: default_configuration
           "isInfix": true
         }
       },
+      "even_number": {
+        "_eq": {
+          "operatorName": "=",
+          "operatorKind": "equal",
+          "argumentType": "even_number",
+          "isInfix": true
+        },
+        "_gt": {
+          "operatorName": ">",
+          "operatorKind": "custom",
+          "argumentType": "even_number",
+          "isInfix": true
+        },
+        "_gte": {
+          "operatorName": ">=",
+          "operatorKind": "custom",
+          "argumentType": "even_number",
+          "isInfix": true
+        },
+        "_in": {
+          "operatorName": "IN",
+          "operatorKind": "in",
+          "argumentType": "even_number",
+          "isInfix": true
+        },
+        "_lt": {
+          "operatorName": "<",
+          "operatorKind": "custom",
+          "argumentType": "even_number",
+          "isInfix": true
+        },
+        "_lte": {
+          "operatorName": "<=",
+          "operatorKind": "custom",
+          "argumentType": "even_number",
+          "isInfix": true
+        },
+        "_neq": {
+          "operatorName": "<>",
+          "operatorKind": "custom",
+          "argumentType": "even_number",
+          "isInfix": true
+        }
+      },
       "float8": {
         "_eq": {
           "operatorName": "=",