feat(explore): Postgres datatype conversion (#13294)

* test

* unnecessary import

* fix lint

* changes

* fix lint

* changes

* changes

* changes

* changes

* answering comments & changes

* answering comments

* answering comments

* changes

* changes

* changes

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

* fix tests

superset/db_engine_specs/postgres.py

@@ -18,14 +18,28 @@ import json
 import logging
 import re
 from datetime import datetime
-from typing import Any, Dict, List, Optional, Tuple, TYPE_CHECKING
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    List,
+    Match,
+    Optional,
+    Pattern,
+    Tuple,
+    TYPE_CHECKING,
+    Union,
+)
 
 from pytz import _FixedOffset  # type: ignore
+from sqlalchemy.dialects.postgresql import ARRAY, DOUBLE_PRECISION, ENUM, JSON
 from sqlalchemy.dialects.postgresql.base import PGInspector
+from sqlalchemy.types import String, TypeEngine
 
 from superset.db_engine_specs.base import BaseEngineSpec
 from superset.exceptions import SupersetException
 from superset.utils import core as utils
+from superset.utils.core import ColumnSpec, GenericDataType
 
 if TYPE_CHECKING:
     from superset.models.core import Database  # pragma: no cover
@@ -77,6 +91,21 @@ class PostgresEngineSpec(PostgresBaseEngineSpec):
     max_column_name_length = 63
     try_remove_schema_from_table_name = False
 
+    column_type_mappings = (
+        (
+            re.compile(r"^double precision", re.IGNORECASE),
+            DOUBLE_PRECISION(),
+            GenericDataType.NUMERIC,
+        ),
+        (
+            re.compile(r"^array.*", re.IGNORECASE),
+            lambda match: ARRAY(int(match[2])) if match[2] else String(),
+            utils.GenericDataType.STRING,
+        ),
+        (re.compile(r"^json.*", re.IGNORECASE), JSON(), utils.GenericDataType.STRING,),
+        (re.compile(r"^enum.*", re.IGNORECASE), ENUM(), utils.GenericDataType.STRING,),
+    )
+
     @classmethod
     def get_allow_cost_estimate(cls, extra: Dict[str, Any]) -> bool:
         return True
@@ -144,3 +173,26 @@ class PostgresEngineSpec(PostgresBaseEngineSpec):
             engine_params["connect_args"] = connect_args
             extra["engine_params"] = engine_params
         return extra
+
+    @classmethod
+    def get_column_spec(  # type: ignore
+        cls,
+        native_type: Optional[str],
+        source: utils.ColumnTypeSource = utils.ColumnTypeSource.GET_TABLE,
+        column_type_mappings: Tuple[
+            Tuple[
+                Pattern[str],
+                Union[TypeEngine, Callable[[Match[str]], TypeEngine]],
+                GenericDataType,
+            ],
+            ...,
+        ] = column_type_mappings,
+    ) -> Union[ColumnSpec, None]:
+
+        column_spec = super().get_column_spec(native_type)
+        if column_spec:
+            return column_spec
+
+        return super().get_column_spec(
+            native_type, column_type_mappings=column_type_mappings
+        )