fix(query): decimal div overflow (databendlabs#15856)

* fix(query): decimal div overflow * fix(query): decimal div overflow * fix(query): decimal div overflow
yufan022 · Jun 22, 2024 · b256d3d · b256d3d
1 parent 85ac9f7
commit b256d3d
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Showing 3 changed files with 45 additions and 4 deletions.
diff --git a/src/query/expression/src/types/decimal.rs b/src/query/expression/src/types/decimal.rs
@@ -348,6 +348,8 @@ pub trait Decimal:
     fn checked_mul(self, rhs: Self) -> Option<Self>;
     fn checked_rem(self, rhs: Self) -> Option<Self>;
 
+    fn do_round_div(self, rhs: Self, mul: Self) -> Option<Self>;
+
     fn min_for_precision(precision: u8) -> Self;
     fn max_for_precision(precision: u8) -> Self;
 
@@ -443,6 +445,16 @@ impl Decimal for i128 {
         self.checked_rem(rhs)
     }
 
+    fn do_round_div(self, rhs: Self, mul: Self) -> Option<Self> {
+        if self.is_negative() == rhs.is_negative() {
+            let res = (i256::from(self) * i256::from(mul) + i256::from(rhs) / 2) / i256::from(rhs);
+            Some(*res.low())
+        } else {
+            let res = (i256::from(self) * i256::from(mul) - i256::from(rhs) / 2) / i256::from(rhs);
+            Some(*res.low())
+        }
+    }
+
     fn min_for_precision(to_precision: u8) -> Self {
         MIN_DECIMAL_FOR_EACH_PRECISION[to_precision as usize - 1]
     }
@@ -647,6 +659,14 @@ impl Decimal for i256 {
         self.checked_rem(rhs)
     }
 
+    fn do_round_div(self, rhs: Self, mul: Self) -> Option<Self> {
+        if self.is_negative() == rhs.is_negative() {
+            self.checked_mul(mul).map(|x| (x + rhs / 2) / rhs)
+        } else {
+            self.checked_mul(mul).map(|x| (x - rhs / 2) / rhs)
+        }
+    }
+
     fn min_for_precision(to_precision: u8) -> Self {
         MIN_DECIMAL256_BYTES_FOR_EACH_PRECISION[to_precision as usize - 1]
     }

diff --git a/src/query/functions/src/scalars/decimal/arithmetic.rs b/src/query/functions/src/scalars/decimal/arithmetic.rs
@@ -88,7 +88,6 @@ macro_rules! binary_decimal {
             let scale_a = $left.scale();
             let scale_b = $right.scale();
 
-
             // Note: the result scale is always larger than the left scale
             let scale_mul = scale_b + $size.scale - scale_a;
             let multiplier = T::e(scale_mul as u32);
@@ -102,10 +101,17 @@ macro_rules! binary_decimal {
                 if std::intrinsics::unlikely(b == zero) {
                     ctx.set_error(result.len(), "divided by zero");
                     result.push(one);
-                } else if a.is_negative() == b.is_negative() {
-                    result.push((a * multiplier + b / 2).div(b));
                 } else {
-                    result.push((a * multiplier - b / 2).div(b));
+                   match a.do_round_div(b, multiplier) {
+                        Some(t) => result.push(t),
+                        None => {
+                            ctx.set_error(
+                                result.len(),
+                                concat!("Decimal overflow at line : ", line!()),
+                            );
+                            result.push(one);
+                        }
+                   }
                 }
             };
 

diff --git a/tests/sqllogictests/suites/base/11_data_type/11_0006_data_type_decimal.test b/tests/sqllogictests/suites/base/11_data_type/11_0006_data_type_decimal.test
@@ -266,6 +266,10 @@ SELECT CAST(987654321.34 AS DECIMAL(76, 2)) / CAST(1.23 AS DECIMAL(76, 2)) AS re
 ----
 802970992.95934959
 
+query I
+SELECT 404.754480000000000000000001 / 563.653044520000000000000001, 404.754480000000000000000000 / 563.653044520000000000000000;
+----
+0.718091535094401799683905 0.718091535094401799683905
 
 ## negative
 
@@ -1114,5 +1118,16 @@ select cast(b as int), cast(c as int), cast(d as int) from t
 -1 -1 -1
 -2 -2 -2
 
+statement ok
+create table decimal_test2(a decimal(28,8), b decimal(24,16));
+
+statement ok
+insert into decimal_test2 values(300.07878791,5325.0000000000000000),(2.00000000,10491.0000000000000000);
+
+query I
+select sum(a * b) / sum(a * b), sum(a + b) / sum(a + b), sum(a - b) / sum(a - b) from decimal_test2;
+----
+1.000000000000000000000000	1.0000000000000000	1.0000000000000000
+
 statement ok
 drop database decimal_t;