MCOL-5708 Calculate precision and scale for constant decimal. (#3227)

This patch calculates precision and scale for constant decimal
value for SUM aggregation function.

datatypes/mcs_datatype.cpp

@@ -58,6 +58,41 @@ int128_t SystemCatalog::TypeAttributesStd::decimal128FromString(const std::strin
   return result;
 }
 
+// SQL parser checks that given `value` is in a valid format.
+// The first symbol can be `-`. The `value` can contain `.` symbol.
+void decimalPrecisionAndScale(const utils::NullString& value, int& precision, int& scale)
+{
+  if (value.isNull())
+  {
+    scale = 0;
+    precision = -1;
+    return;
+  }
+
+  const auto strValue = value.unsafeStringRef();
+  if (strValue.empty())
+  {
+    scale = 0;
+    precision = -1;
+    return;
+  }
+
+  const int len = strValue.size();
+  const auto dotIndex = strValue.find('.');
+  const int minExists = strValue.front() == '-' ? 1 : 0;
+
+  if (dotIndex == std::string::npos)
+  {
+    scale = 0;
+    precision = len - minExists;
+  }
+  else
+  {
+    scale = len - dotIndex - 1;
+    precision = len - 1 - minExists;
+  }
+}
+
 int128_t SystemCatalog::TypeAttributesStd::decimal128FromString(const utils::NullString& value,
                                                                 bool* saturate) const
 {

datatypes/mcs_datatype.h

@@ -125,6 +125,8 @@ struct WidthToSIntegralType<16> : _WidthToSIntegralType<16, int128_t>
 {
 };
 
+void decimalPrecisionAndScale(const utils::NullString& value, int& precision, int& scale);
+
 class SystemCatalog
 {
  public:

mysql-test/columnstore/bugfixes/mcol-5708.result

@@ -0,0 +1,17 @@
+DROP DATABASE IF EXISTS mcol_5708;
+CREATE DATABASE mcol_5708;
+USE mcol_5708;
+CREATE TABLE test (
+`f_int` int(10) unsigned NOT NULL DEFAULT 0,
+`f_dec14x2` decimal(14,2) NOT NULL DEFAULT 0.00,
+`f_dec14x4` decimal(14,4) NOT NULL DEFAULT 0.0000
+) ENGINE=columnstore DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci;
+insert into test (f_int,f_dec14x4, f_dec14x2) values (1, 0.1, 0.1);
+select
+f_int, sum(f_dec14x2), sum(f_dec14x4),
+sum(-200.000001), sum(0), sum(0.0), sum(11.000011), sum(12e-4), sum(1e+4),
+sum(-0.0), sum(-1 - 1.1), sum(--12), sum(+20), sum(13)
+from test group by 1;
+f_int	sum(f_dec14x2)	sum(f_dec14x4)	sum(-200.000001)	sum(0)	sum(0.0)	sum(11.000011)	sum(12e-4)	sum(1e+4)	sum(-0.0)	sum(-1 - 1.1)	sum(--12)	sum(+20)	sum(13)
+1	0.10	0.1000	-200.000001	0	0.0	11.000011	0.0012	10000	0.0	-2.1	12	20	13
+DROP DATABASE mcol_5708;

mysql-test/columnstore/bugfixes/mcol-5708.test

@@ -0,0 +1,31 @@
+#
+# MCOL-5708
+#
+
+--source ../include/have_columnstore.inc
+
+--disable_warnings
+DROP DATABASE IF EXISTS mcol_5708;
+--enable_warnings
+CREATE DATABASE mcol_5708;
+USE mcol_5708;
+
+CREATE TABLE test (
+  `f_int` int(10) unsigned NOT NULL DEFAULT 0,
+  `f_dec14x2` decimal(14,2) NOT NULL DEFAULT 0.00,
+  `f_dec14x4` decimal(14,4) NOT NULL DEFAULT 0.0000
+) ENGINE=columnstore DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci;
+
+
+insert into test (f_int,f_dec14x4, f_dec14x2) values (1, 0.1, 0.1);
+
+select
+f_int, sum(f_dec14x2), sum(f_dec14x4),
+sum(-200.000001), sum(0), sum(0.0), sum(11.000011), sum(12e-4), sum(1e+4),
+sum(-0.0), sum(-1 - 1.1), sum(--12), sum(+20), sum(13)
+from test group by 1;
+
+
+--disable_warnings
+DROP DATABASE mcol_5708;
+--enable_warnings

utils/rowgroup/rowaggregation.cpp

@@ -3702,10 +3702,13 @@ void RowAggregationUM::doNotNullConstantAggregate(const ConstantAggData& aggData
           auto width = fRow.getColumnWidth(colOut);
           if (width == datatypes::MAXDECIMALWIDTH)
           {
+            int precision, scale;
+            // MCOL-5708 Calculate precision and scale based on the given value.
+            datatypes::decimalPrecisionAndScale(aggData.fConstValue, precision, scale);
             execplan::CalpontSystemCatalog::TypeHolderStd colType;
             colType.colWidth = width;
-            colType.precision = fRow.getPrecision(i);
+            colType.precision = precision;
-            colType.scale = fRow.getScale(i);
+            colType.scale = scale;
             colType.colDataType = colDataType;
             int128_t constValue = colType.decimal128FromString(aggData.fConstValue);
             int128_t sum;