From 7fe7c01125a57d9d9103cac89dba390888dfba90 Mon Sep 17 00:00:00 2001
From: Gabriel <gabrielleebuaa@gmail.com>
Date: Tue, 25 Oct 2022 12:08:49 +0800
Subject: [PATCH] [Bug](decimal) Fix incorrect result for decimal multiply
 (#13591)

Fix incorrect result for decimal multiply
---
 be/src/vec/functions/multiply.cpp             |  6 +++-
 .../math_functions/test_multiply.out          |  9 +++++
 .../math_functions/test_multiply.groovy       | 33 +++++++++++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 regression-test/data/query_p0/sql_functions/math_functions/test_multiply.out
 create mode 100644 regression-test/suites/query_p0/sql_functions/math_functions/test_multiply.groovy

diff --git a/be/src/vec/functions/multiply.cpp b/be/src/vec/functions/multiply.cpp
index c6f3d88d598ebc..e55a8549e56490 100644
--- a/be/src/vec/functions/multiply.cpp
+++ b/be/src/vec/functions/multiply.cpp
@@ -48,8 +48,12 @@ struct MultiplyImpl {
         int8 sgn[size];
 
         for (int i = 0; i < size; i++) {
-            sgn[i] = ((DecimalV2Value(a[i]).value() >= 0) == (DecimalV2Value(b[i]).value() >= 0))
+            sgn[i] = ((DecimalV2Value(a[i]).value() > 0) && (DecimalV2Value(b[i]).value() > 0)) ||
+                                     ((DecimalV2Value(a[i]).value() < 0) &&
+                                      (DecimalV2Value(b[i]).value() < 0))
                              ? 1
+                     : ((DecimalV2Value(a[i]).value() == 0) || (DecimalV2Value(b[i]).value() == 0))
+                             ? 0
                              : -1;
         }
 
diff --git a/regression-test/data/query_p0/sql_functions/math_functions/test_multiply.out b/regression-test/data/query_p0/sql_functions/math_functions/test_multiply.out
new file mode 100644
index 00000000000000..4611fe72880f32
--- /dev/null
+++ b/regression-test/data/query_p0/sql_functions/math_functions/test_multiply.out
@@ -0,0 +1,9 @@
+-- This file is automatically generated. You should know what you did if you want to edit this
+-- !select --
+0E-9
+0E-9
+
+-- !select --
+\N
+0E-9
+
diff --git a/regression-test/suites/query_p0/sql_functions/math_functions/test_multiply.groovy b/regression-test/suites/query_p0/sql_functions/math_functions/test_multiply.groovy
new file mode 100644
index 00000000000000..cdea8f00266476
--- /dev/null
+++ b/regression-test/suites/query_p0/sql_functions/math_functions/test_multiply.groovy
@@ -0,0 +1,33 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+suite("test_multiply") {
+    sql """ set enable_vectorized_engine = true """
+
+    def tableName = "test_multiply"
+    sql """ CREATE TABLE `${tableName}` (
+        `user_id` LARGEINT NOT NULL COMMENT "用户id",
+        `col2` DECIMAL(27,9) COMMENT "数据灌入日期时间",
+        `col3` DECIMAL(16,8) COMMENT "数据灌入日期时间")
+        DUPLICATE KEY(`user_id`) DISTRIBUTED BY HASH(`user_id`)
+        PROPERTIES ( "replication_num" = "1" ); """
+
+    sql """ insert into `${tableName}` values(1,null,2.2); """
+    sql """ insert into `${tableName}` values(1,0,0); """
+    qt_select """ select COALESCE(col2, 0) * COALESCE(col3, 0) from `${tableName}`; """
+    qt_select """ select col2 * col3 from `${tableName}`; """
+}