From 1bcf63a436c8e1bacdfd9ef0eb772a9682f43edd Mon Sep 17 00:00:00 2001
From: Akhmad Oripov <96055449+AestheticAkhmad@users.noreply.github.com>
Date: Mon, 31 Mar 2025 15:59:40 +0200
Subject: [PATCH] Fix(MCOL-4611): mod loses precision on huge narrow decimal
 (#3473)

---
 .../columnstore/bugfixes/mcol_4611.result     | 17 +++++++++++
 .../columnstore/bugfixes/mcol_4611.test       | 28 +++++++++++++++++++
 utils/funcexp/func_mod.cpp                    |  2 +-
 utils/funcexp/functor_real.h                  |  2 +-
 4 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 mysql-test/columnstore/bugfixes/mcol_4611.result
 create mode 100644 mysql-test/columnstore/bugfixes/mcol_4611.test

diff --git a/mysql-test/columnstore/bugfixes/mcol_4611.result b/mysql-test/columnstore/bugfixes/mcol_4611.result
new file mode 100644
index 000000000..21cd1e0ad
--- /dev/null
+++ b/mysql-test/columnstore/bugfixes/mcol_4611.result
@@ -0,0 +1,17 @@
+DROP DATABASE IF EXISTS mcol_4611;
+CREATE DATABASE mcol_4611;
+USE mcol_4611;
+DROP TABLE IF EXISTS t1;
+CREATE TABLE t1 (a DECIMAL(18,0)) ENGINE=ColumnStore;
+INSERT INTO t1 VALUES (999999999999999999);
+SELECT a MOD 10000 FROM t1;
+a MOD 10000
+9999
+DROP TABLE IF EXISTS t1;
+CREATE TABLE t1 (a DECIMAL(18,0)) ENGINE=ColumnStore;
+INSERT INTO t1 VALUES (999999999999999999);
+SELECT RAND(9999), RAND(a MOD 10000) FROM t1;
+RAND(9999)	RAND(a MOD 10000)
+0.7361292641015065	0.7361292641015065
+DROP TABLE IF EXISTS t1;
+DROP DATABASE mcol_4611;
diff --git a/mysql-test/columnstore/bugfixes/mcol_4611.test b/mysql-test/columnstore/bugfixes/mcol_4611.test
new file mode 100644
index 000000000..f96ee3120
--- /dev/null
+++ b/mysql-test/columnstore/bugfixes/mcol_4611.test
@@ -0,0 +1,28 @@
+-- source ../include/have_columnstore.inc
+--disable_warnings
+DROP DATABASE IF EXISTS mcol_4611;
+--enable_warnings
+CREATE DATABASE mcol_4611;
+USE mcol_4611;
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+CREATE TABLE t1 (a DECIMAL(18,0)) ENGINE=ColumnStore;
+INSERT INTO t1 VALUES (999999999999999999);
+SELECT a MOD 10000 FROM t1;
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+CREATE TABLE t1 (a DECIMAL(18,0)) ENGINE=ColumnStore;
+INSERT INTO t1 VALUES (999999999999999999);
+SELECT RAND(9999), RAND(a MOD 10000) FROM t1;
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+--enable_warnings
+
+--disable_warnings
+DROP DATABASE mcol_4611;
+--enable_warnings
diff --git a/utils/funcexp/func_mod.cpp b/utils/funcexp/func_mod.cpp
index 11c542168..a7b99430a 100644
--- a/utils/funcexp/func_mod.cpp
+++ b/utils/funcexp/func_mod.cpp
@@ -106,7 +106,7 @@ IDB_Decimal Func_mod::getDecimalVal(Row& row, FunctionParm& parm, bool& isNull,
   }
 
   IDB_Decimal d = parm[0]->data()->getDecimalVal(row, isNull);
-  int64_t value = d.value / pow(10.0, d.scale);
+  int64_t value = d.value / static_cast<int64_t>(pow(10.0, d.scale));
   int lefto = d.value % (int)pow(10.0, d.scale);
 
   int64_t mod = (value % div) * pow(10.0, d.scale) + lefto;
diff --git a/utils/funcexp/functor_real.h b/utils/funcexp/functor_real.h
index a2f0e608d..1c5fdc75d 100644
--- a/utils/funcexp/functor_real.h
+++ b/utils/funcexp/functor_real.h
@@ -381,7 +381,7 @@ class Func_mod : public Func_Real
         return static_cast<ModType>(integralRemainder.toTFloat128() + intAndFract.second);
       }
     }
-    int64_t value = d.value / pow(10.0, d.scale);
+    int64_t value = d.value / static_cast<int64_t>(pow(10.0, d.scale));
     return value % div;
   }
 };