fix(function): the add and minus functions of decimal do not select the correct precision (#18161)

fix: The add and minus functions of decimal do not select the correct precision

Author: forsaken628

src/query/functions/src/scalars/decimal/src/arithmetic.rs

@@ -128,19 +128,9 @@ impl ArithmeticOp {
                 ))
             }
 
-            ArithmeticOp::Plus | ArithmeticOp::Minus => Some((
-                if scale == a.scale() {
-                    *a
-                } else {
-                    DecimalSize::new(a.precision(), scale).ok()?
-                },
-                if scale == b.scale() {
-                    *b
-                } else {
-                    DecimalSize::new(b.precision(), scale).ok()?
-                },
-                result_type,
-            )),
+            ArithmeticOp::Plus | ArithmeticOp::Minus => {
+                Some((result_type, result_type, result_type))
+            }
         }
     }
 }

src/query/functions/src/test_utils.rs

@@ -43,7 +43,7 @@ use crate::BUILTIN_FUNCTIONS;
 
 pub fn parse_raw_expr(text: &str, columns: &[(&str, DataType)]) -> RawExpr {
     let tokens = tokenize_sql(text).unwrap();
-    let expr = parse_expr(&tokens, Dialect::PostgreSQL).unwrap();
+    let expr = parse_expr(&tokens, Dialect::PostgreSQL).expect("failed to parse expr");
     transform_expr(expr, columns)
 }
 

src/query/functions/tests/it/scalars/arithmetic.rs

@@ -319,5 +319,10 @@ fn test_decimal() {
             columns: &columns,
             ..Default::default()
         },
-    )
+    );
+
+    run_ast_with_context(file, "1964831797.0000 - 0.0214642400000", TestContext {
+        columns: &columns,
+        ..Default::default()
+    })
 }

src/query/functions/tests/it/scalars/testdata/arithmetic_decimal.txt

@@ -29,3 +29,12 @@ evaluation (internal):
 +-----------------+------------------------------------------------------------------------------------------------------------------+
 
 
+ast            : 1964831797.0000 - 0.0214642400000
+raw expr       : minus(1964831797.0000, 0.0214642400000)
+checked expr   : minus<Decimal(14, 4), Decimal(13, 13)>(1964831797.0000_d128(14,4), 0.0214642400000_d128(13,13))
+optimized expr : 1964831796.9785357600000_d128(24,13)
+output type    : Decimal(24, 13)
+output domain  : {1964831796.9785357600000..=1964831796.9785357600000}
+output         : 1964831796.9785357600000
+
+