Bugfix to include size, scale and precision in column.datatype

1. Fixes Bug #29
2. Introduced new class OracleColumn which can be used to define logic specific to Oracle table column
3. Added an example model in dbt_adbs_test_project to reproduce the error and validate the fix
4. Added a project specific macro in dbt_adbs_test_project to translate the string datatype

dbt/adapters/oracle/column.py

@@ -0,0 +1,52 @@
+from dataclasses import dataclass
+from typing import Dict, ClassVar
+
+
+from dbt.adapters.base.column import Column
+
+
+@dataclass
+class OracleColumn(Column):
+    # https://docs.oracle.com/en/database/oracle/oracle-database/21/sqlrf/Data-Types.html#GUID-A3C0D836-BADB-44E5-A5D4-265BA5968483
+
+    TYPE_LABELS: ClassVar[Dict[str, str]] = {
+        "STRING": "VARCHAR2(4000)",
+        "TIMESTAMP": "TIMESTAMP",
+        "FLOAT": "FLOAT",
+        "INTEGER": "INTEGER",
+    }
+
+    STRING_DATATYPES = {'char', 'nchar', 'varchar', 'varchar2', 'nvarchar2'}
+    NUMBER_DATATYPES = {'number', 'float'}
+
+    @property
+    def data_type(self) -> str:
+        if self.is_string():
+            return self.oracle_string_type(self.dtype, self.string_size())
+        elif self.is_numeric():
+            return self.numeric_type(self.dtype, self.numeric_precision, self.numeric_scale)
+        else:
+            return self.dtype
+
+    @classmethod
+    def oracle_string_type(cls, dtype: str, size: int = None):
+        """
+            - CHAR(SIZE)
+            - VARCHAR2(SIZE)
+            - NCHAR(SIZE) or NCHAR
+            - NVARCHAR2(SIZE)
+        """
+        if size is None:
+            return dtype
+        else:
+            return "{}({})".format(dtype, size)
+
+    def is_numeric(self) -> bool:
+        if self.dtype.lower() in self.NUMBER_DATATYPES:
+            return True
+        return super().is_numeric()
+
+    def is_string(self) -> bool:
+        if self.dtype.lower() in self.STRING_DATATYPES:
+            return True
+        return super().is_string()

dbt/adapters/oracle/impl.py

@@ -25,6 +25,7 @@
 from dbt.adapters.sql import SQLAdapter
 from dbt.adapters.base.meta import available
 from dbt.adapters.oracle import OracleAdapterConnectionManager
+from dbt.adapters.oracle.column import OracleColumn
 from dbt.adapters.oracle.relation import OracleRelation
 from dbt.contracts.graph.manifest import Manifest
 
@@ -69,6 +70,7 @@
 class OracleAdapter(SQLAdapter):
     ConnectionManager = OracleAdapterConnectionManager
     Relation = OracleRelation
+    Column = OracleColumn
 
     def debug_query(self) -> None:
         self.execute("select 1 as id from dual")

dbt_adbs_test_project/macros/datatypes.sql

@@ -0,0 +1,3 @@
+{%- macro oracle__type_string() -%}
+    VARCHAR2(4000)
+{%- endmacro -%}

dbt_adbs_test_project/models/union_customer_sales.sql

@@ -0,0 +1,7 @@
+{{ config(materialized='table')}}
+{{
+    dbt_utils.union_relations(
+        relations=[source('sh_database', 'sales'),
+                   source('sh_database', 'customers')],
+        source_column_name='dbt_source_relation')
+}}