[PECO-1109] Parameterized Query: add suport for inferring decimal types (#228)

Signed-off-by: Jesse Whitehouse <jesse.whitehouse@databricks.com>

Author: Jesse

src/databricks/sql/utils.py

@@ -1,25 +1,26 @@
 from __future__ import annotations
+
+import copy
+import datetime
+import decimal
 from abc import ABC, abstractmethod
-from collections import namedtuple, OrderedDict
+from collections import OrderedDict, namedtuple
 from collections.abc import Iterable
 from decimal import Decimal
-import datetime
-import decimal
 from enum import Enum
+from typing import Any, Dict, List, Union
+
 import lz4.frame
-from typing import Dict, List, Union, Any
 import pyarrow
-from enum import Enum
-import copy
 
-from databricks.sql import exc, OperationalError
+from databricks.sql import OperationalError, exc
 from databricks.sql.cloudfetch.download_manager import ResultFileDownloadManager
 from databricks.sql.thrift_api.TCLIService.ttypes import (
-    TSparkArrowResultLink,
-    TSparkRowSetType,
     TRowSet,
+    TSparkArrowResultLink,
     TSparkParameter,
     TSparkParameterValue,
+    TSparkRowSetType,
 )
 
 BIT_MASKS = [1, 2, 4, 8, 16, 32, 64, 128]
@@ -478,6 +479,10 @@ def _create_arrow_array(t_col_value_wrapper, arrow_type):
 
 
 class DbSqlType(Enum):
+    """The values of this enumeration are passed as literals to be used in a CAST
+    evaluation by the thrift server.
+    """
+
     STRING = "STRING"
     DATE = "DATE"
     TIMESTAMP = "TIMESTAMP"
@@ -495,7 +500,7 @@ class DbSqlType(Enum):
 class DbSqlParameter:
     name: str
     value: Any
-    type: DbSqlType
+    type: Union[DbSqlType, DbsqlDynamicDecimalType, Enum]
 
     def __init__(self, name="", value=None, type=None):
         self.name = name
@@ -506,6 +511,11 @@ def __eq__(self, other):
         return isinstance(other, self.__class__) and self.__dict__ == other.__dict__
 
 
+class DbsqlDynamicDecimalType:
+    def __init__(self, value):
+        self.value = value
+
+
 def named_parameters_to_dbsqlparams_v1(parameters: Dict[str, str]):
     dbsqlparams = []
     for name, parameter in parameters.items():
@@ -531,16 +541,49 @@ def infer_types(params: list[DbSqlParameter]):
         datetime.datetime: DbSqlType.TIMESTAMP,
         datetime.date: DbSqlType.DATE,
         bool: DbSqlType.BOOLEAN,
+        Decimal: DbSqlType.DECIMAL,
     }
-    newParams = copy.deepcopy(params)
-    for param in newParams:
+    new_params = copy.deepcopy(params)
+    for param in new_params:
         if not param.type:
             if type(param.value) in type_lookup_table:
                 param.type = type_lookup_table[type(param.value)]
             else:
                 raise ValueError("Parameter type cannot be inferred")
+
+        if param.type == DbSqlType.DECIMAL:
+            cast_exp = calculate_decimal_cast_string(param.value)
+            param.type = DbsqlDynamicDecimalType(cast_exp)
+
         param.value = str(param.value)
-    return newParams
+    return new_params
+
+
+def calculate_decimal_cast_string(input: Decimal) -> str:
+    """Returns the smallest SQL cast argument that can contain the passed decimal
+
+    Example:
+        Input:   Decimal("1234.5678")
+        Output:  DECIMAL(8,4)
+    """
+
+    string_decimal = str(input)
+
+    if string_decimal.startswith("0."):
+        # This decimal is less than 1
+        overall = after = len(string_decimal) - 2
+    elif "." not in string_decimal:
+        # This decimal has no fractional component
+        overall = len(string_decimal)
+        after = 0
+    else:
+        # This decimal has both whole and fractional parts
+        parts = string_decimal.split(".")
+        parts_lengths = [len(i) for i in parts]
+        before, after = parts_lengths[:2]
+        overall = before + after
+
+    return f"DECIMAL({overall},{after})"
 
 
 def named_parameters_to_tsparkparams(parameters: Union[List[Any], Dict[str, str]]):

tests/e2e/common/parameterized_query_tests.py

@@ -1,11 +1,22 @@
 import datetime
 from decimal import Decimal
+from enum import Enum
 from typing import Dict, List, Tuple, Union
 
 import pytz
 
-from databricks.sql.client import Connection
-from databricks.sql.utils import DbSqlParameter, DbSqlType
+from databricks.sql.exc import DatabaseError
+from databricks.sql.utils import (
+    DbSqlParameter,
+    DbSqlType,
+    calculate_decimal_cast_string,
+)
+
+
+class MyCustomDecimalType(Enum):
+    DECIMAL_38_0 = "DECIMAL(38,0)"
+    DECIMAL_38_2 = "DECIMAL(38,2)"
+    DECIMAL_18_9 = "DECIMAL(18,9)"
 
 
 class PySQLParameterizedQueryTestSuiteMixin:
@@ -63,6 +74,11 @@ def test_primitive_inferred_string(self):
         result = self._get_one_result(self.QUERY, params)
         assert result.col == "Hello"
 
+    def test_primitive_inferred_decimal(self):
+        params = {"p": Decimal("1234.56")}
+        result = self._get_one_result(self.QUERY, params)
+        assert result.col == Decimal("1234.56")
+
     def test_dbsqlparam_inferred_bool(self):
 
         params = [DbSqlParameter(name="p", value=True, type=None)]
@@ -103,6 +119,11 @@ def test_dbsqlparam_inferred_string(self):
         result = self._get_one_result(self.QUERY, params)
         assert result.col == "Hello"
 
+    def test_dbsqlparam_inferred_decimal(self):
+        params = [DbSqlParameter(name="p", value=Decimal("1234.56"), type=None)]
+        result = self._get_one_result(self.QUERY, params)
+        assert result.col == Decimal("1234.56")
+
     def test_dbsqlparam_explicit_bool(self):
 
         params = [DbSqlParameter(name="p", value=True, type=DbSqlType.BOOLEAN)]
@@ -142,3 +163,50 @@ def test_dbsqlparam_explicit_string(self):
         params = [DbSqlParameter(name="p", value="Hello", type=DbSqlType.STRING)]
         result = self._get_one_result(self.QUERY, params)
         assert result.col == "Hello"
+
+    def test_dbsqlparam_explicit_decimal(self):
+        params = [
+            DbSqlParameter(name="p", value=Decimal("1234.56"), type=DbSqlType.DECIMAL)
+        ]
+        result = self._get_one_result(self.QUERY, params)
+        assert result.col == Decimal("1234.56")
+
+    def test_dbsqlparam_custom_explicit_decimal_38_0(self):
+
+        # This DECIMAL can be contained in a DECIMAL(38,0) column in Databricks
+        value = Decimal("12345678912345678912345678912345678912")
+        params = [
+            DbSqlParameter(name="p", value=value, type=MyCustomDecimalType.DECIMAL_38_0)
+        ]
+        result = self._get_one_result(self.QUERY, params)
+        assert result.col == value
+
+    def test_dbsqlparam_custom_explicit_decimal_38_2(self):
+
+        # This DECIMAL can be contained in a DECIMAL(38,2) column in Databricks
+        value = Decimal("123456789123456789123456789123456789.12")
+        params = [
+            DbSqlParameter(name="p", value=value, type=MyCustomDecimalType.DECIMAL_38_2)
+        ]
+        result = self._get_one_result(self.QUERY, params)
+        assert result.col == value
+
+    def test_dbsqlparam_custom_explicit_decimal_18_9(self):
+
+        # This DECIMAL can be contained in a DECIMAL(18,9) column in Databricks
+        value = Decimal("123456789.123456789")
+        params = [
+            DbSqlParameter(name="p", value=value, type=MyCustomDecimalType.DECIMAL_18_9)
+        ]
+        result = self._get_one_result(self.QUERY, params)
+        assert result.col == value
+
+    def test_calculate_decimal_cast_string(self):
+
+        assert calculate_decimal_cast_string(Decimal("10.00")) == "DECIMAL(4,2)"
+        assert (
+            calculate_decimal_cast_string(
+                Decimal("123456789123456789.123456789123456789")
+            )
+            == "DECIMAL(36,18)"
+        )

tests/unit/test_parameters.py

@@ -3,6 +3,8 @@
     infer_types,
     named_parameters_to_dbsqlparams_v1,
     named_parameters_to_dbsqlparams_v2,
+    calculate_decimal_cast_string,
+    DbsqlDynamicDecimalType
 )
 from databricks.sql.thrift_api.TCLIService.ttypes import (
     TSparkParameter,
@@ -11,6 +13,10 @@
 from databricks.sql.utils import DbSqlParameter, DbSqlType
 import pytest
 
+from decimal import Decimal
+
+from typing import List
+
 
 class TestTSparkParameterConversion(object):
     def test_conversion_e2e(self):
@@ -31,7 +37,7 @@ def test_conversion_e2e(self):
                 name="", type="FLOAT", value=TSparkParameterValue(stringValue="1.0")
             ),
             TSparkParameter(
-                name="", type="DECIMAL", value=TSparkParameterValue(stringValue="1.0")
+                name="", type="DECIMAL(2,1)", value=TSparkParameterValue(stringValue="1.0")
             ),
         ]
 
@@ -53,23 +59,64 @@ def test_basic_conversions_v2(self):
             DbSqlParameter("3", "foo"),
         ]
 
-    def test_type_inference(self):
+    def test_infer_types_none(self):
         with pytest.raises(ValueError):
             infer_types([DbSqlParameter("", None)])
+
+    def test_infer_types_dict(self):
         with pytest.raises(ValueError):
             infer_types([DbSqlParameter("", {1: 1})])
-        assert infer_types([DbSqlParameter("", 1)]) == [
-            DbSqlParameter("", "1", DbSqlType.INTEGER)
-        ]
-        assert infer_types([DbSqlParameter("", True)]) == [
-            DbSqlParameter("", "True", DbSqlType.BOOLEAN)
-        ]
-        assert infer_types([DbSqlParameter("", 1.0)]) == [
-            DbSqlParameter("", "1.0", DbSqlType.FLOAT)
-        ]
-        assert infer_types([DbSqlParameter("", "foo")]) == [
-            DbSqlParameter("", "foo", DbSqlType.STRING)
-        ]
-        assert infer_types([DbSqlParameter("", 1.0, DbSqlType.DECIMAL)]) == [
-            DbSqlParameter("", "1.0", DbSqlType.DECIMAL)
-        ]
+
+    def test_infer_types_integer(self):
+        input = DbSqlParameter("", 1)
+        output = infer_types([input])
+        assert output == [DbSqlParameter("", "1", DbSqlType.INTEGER)]
+
+    def test_infer_types_boolean(self):
+        input = DbSqlParameter("", True)
+        output = infer_types([input])
+        assert output == [DbSqlParameter("", "True", DbSqlType.BOOLEAN)]
+
+    def test_infer_types_float(self):
+        input = DbSqlParameter("", 1.0)
+        output = infer_types([input])
+        assert output == [DbSqlParameter("", "1.0", DbSqlType.FLOAT)]
+
+    def test_infer_types_string(self):
+        input = DbSqlParameter("", "foo")
+        output = infer_types([input])
+        assert output == [DbSqlParameter("", "foo", DbSqlType.STRING)]
+
+    def test_infer_types_decimal(self):
+        # The output decimal will have a dynamically calculated decimal type with a value of DECIMAL(2,1)
+        input = DbSqlParameter("", Decimal("1.0"))
+        output: List[DbSqlParameter] = infer_types([input])
+        
+        x = output[0]
+
+        assert x.value == "1.0"
+        assert isinstance(x.type, DbsqlDynamicDecimalType)
+        assert x.type.value == "DECIMAL(2,1)"
+       
+
+class TestCalculateDecimalCast(object):
+
+    def test_38_38(self):
+        input = Decimal(".12345678912345678912345678912345678912")
+        output = calculate_decimal_cast_string(input)
+        assert output == "DECIMAL(38,38)"
+    
+    def test_18_9(self):
+        input = Decimal("123456789.123456789")
+        output = calculate_decimal_cast_string(input)
+        assert output == "DECIMAL(18,9)"
+    
+    def test_38_0(self):
+        input = Decimal("12345678912345678912345678912345678912")
+        output = calculate_decimal_cast_string(input)
+        assert output == "DECIMAL(38,0)"
+
+    def test_6_2(self):
+        input = Decimal("1234.56")
+        output = calculate_decimal_cast_string(input)
+        assert output == "DECIMAL(6,2)"