fix: oracle decimal type error

awswrangler/oracle.py

@@ -606,9 +606,12 @@ def detect_oracle_decimal_datatype(cursor: Any) -> dict[str, pa.DataType]:
     _logger.debug("cursor type: %s", type(cursor))
     if isinstance(cursor, oracledb.Cursor):
         # Oracle stores DECIMAL as the NUMBER type
-        for row in cursor.description:
-            if row[1] == oracledb.DB_TYPE_NUMBER and row[5] > 0:
-                dtype[row[0]] = pa.decimal128(row[4], row[5])
+
+        for name, db_type, display_size, internal_size, precision, scale, null_ok in cursor.description:
+            _logger.debug((name, db_type, display_size, internal_size, precision, scale, null_ok))
+
+            if db_type == oracledb.DB_TYPE_NUMBER and scale is not None and scale > 0:
+                dtype[name] = pa.decimal128(precision, scale)
 
     _logger.debug("decimal dtypes: %s", dtype)
     return dtype

tests/unit/test_oracle.py

@@ -254,3 +254,15 @@ def test_dfs_are_equal_for_different_chunksizes(
     df["c1"] = df["c1"].astype("string")
 
     assert df.equals(df2)
+
+
+def test_decimal_columns_none(oracle_table: str, oracle_con: "oracledb.Connection") -> None:
+    create_table_sql = (
+        f'CREATE TABLE "TEST"."{oracle_table}"("VARCOL" VARCHAR2(200),"INTCOL" INTEGER,"NUMCOL" NUMERIC(38, 10))'
+    )
+
+    with oracle_con.cursor() as cursor:
+        cursor.execute(create_table_sql)
+        oracle_con.commit()
+
+    wr.oracle.read_sql_query(f"SELECT * FROM all_tab_columns WHERE table_name = '{oracle_table}'", oracle_con)