Implement Spark decimal multiply and divide

CMake/resolve_dependency_modules/boost/CMakeLists.txt

@@ -53,6 +53,7 @@ set(BOOST_HEADER_ONLY
     circular_buffer
     math
     multi_index
+    multiprecision
     numeric_conversion
     random
     uuid

velox/docs/functions/spark/math.rst

@@ -51,12 +51,25 @@ Mathematical Functions
 .. spark:function:: divide(x, y) -> double
 
     Returns the results of dividing x by y. Performs floating point division.
+    Supported type is DOUBLE.
     Corresponds to Spark's operator ``/``. ::
 
         SELECT 3 / 2; -- 1.5
         SELECT 2L / 2L; -- 1.0
         SELECT 3 / 0; -- NULL
 
+.. spark:function:: divide(x, y) -> decimal
+
+    Returns the results of dividing x by y.
+    Supported type is DECIMAL which can be different precision and scale.
+    Performs floating point division.
+    The result type depends on the precision and scale of x and y.
+    Overflow results return null. Corresponds to Spark's operator ``/``. ::
+
+        SELECT CAST(1 as DECIMAL(17, 3)) / CAST(2 as DECIMAL(17, 3)); -- decimal 0.500000000000000000000
+        SELECT CAST(1 as DECIMAL(20, 3)) / CAST(20 as DECIMAL(20, 2)); -- decimal 0.0500000000000000000
+        SELECT CAST(1 as DECIMAL(20, 3)) / CAST(0 as DECIMAL(20, 3)); -- NULL
+
 .. spark:function:: exp(x) -> double
 
     Returns Euler's number raised to the power of ``x``.
@@ -89,6 +102,17 @@ Mathematical Functions
     Returns the result of multiplying x by y. The types of x and y must be the same.
     For integral types, overflow results in an error. Corresponds to Spark's operator ``*``.
 
+.. spark:function:: multiply(x, y) -> [decimal]
+
+    Returns the result of multiplying x by y. The types of x and y must be decimal which can be different precision and scale.
+    The result type depends on the precision and scale of x and y.
+    Overflow results return null. Corresponds to Spark's operator ``*``. ::
+
+        SELECT CAST(1 as DECIMAL(17, 3)) * CAST(2 as DECIMAL(17, 3)); -- decimal 2.000000
+        SELECT CAST(1 as DECIMAL(20, 3)) * CAST(20 as DECIMAL(20, 2)); -- decimal 20.00000
+        SELECT CAST(1 as DECIMAL(20, 3)) * CAST(0 as DECIMAL(20, 3)); -- decimal 0.000000
+        SELECT CAST(201e-38 as DECIMAL(38, 38)) * CAST(301e-38 as DECIMAL(38, 38)); -- decimal 0.0000000000000000000000000000000000000
+
 .. spark:function:: not(x) -> boolean
 
     Logical not. ::

velox/functions/sparksql/CMakeLists.txt

@@ -17,6 +17,7 @@ add_library(
   ArraySort.cpp
   Bitwise.cpp
   Comparisons.cpp
+  DecimalArithmetic.cpp
   Hash.cpp
   In.cpp
   LeastGreatest.cpp