From bda1355c0a113294b10017e736185738799db23a Mon Sep 17 00:00:00 2001
From: LiBinfeng <1204975323@qq.com>
Date: Wed, 21 Aug 2024 18:07:45 +0800
Subject: [PATCH 1/3] [fix](Nereids) fix fold constant by be return type
 mismatched

---
 .../rules/expression/rules/FoldConstantRuleOnBE.java        | 6 +++++-
 .../expression/fold_constant/fold_constant_by_be.groovy     | 5 +++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java
index d133eac32baddb..637c52e7c2ce2c 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java
@@ -176,7 +176,11 @@ private static Expression replace(
             if (newChild != child) {
                 hasNewChildren = true;
             }
-            newChildren.add(newChild);
+            if (newChild.getDataType() != child.getDataType()) {
+                newChildren.add(newChild.castTo(child.getDataType()));
+            } else {
+                newChildren.add(newChild);
+            }
         }
         return hasNewChildren ? root.withChildren(newChildren) : root;
     }
diff --git a/regression-test/suites/nereids_p0/expression/fold_constant/fold_constant_by_be.groovy b/regression-test/suites/nereids_p0/expression/fold_constant/fold_constant_by_be.groovy
index 809b8e8b291d23..668e88c6f04944 100644
--- a/regression-test/suites/nereids_p0/expression/fold_constant/fold_constant_by_be.groovy
+++ b/regression-test/suites/nereids_p0/expression/fold_constant/fold_constant_by_be.groovy
@@ -53,4 +53,9 @@ suite("fold_constant_by_be") {
 
     sql 'set query_timeout=12;'
     qt_sql "select sleep(sign(1)*5);"
+    
+    explain {
+        sql("verbose select substring('123456', 1, 3)")
+        contains "varchar(3)"
+    }
 }

From 5b9da22ed9a44c545d656551ffe5009cfb3ebc10 Mon Sep 17 00:00:00 2001
From: LiBinfeng <1204975323@qq.com>
Date: Thu, 12 Sep 2024 17:20:56 +0800
Subject: [PATCH 2/3] fix comment

---
 .../nereids/rules/expression/rules/FoldConstantRuleOnBE.java    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java
index 637c52e7c2ce2c..b237a3d6c5eed6 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java
@@ -176,7 +176,7 @@ private static Expression replace(
             if (newChild != child) {
                 hasNewChildren = true;
             }
-            if (newChild.getDataType() != child.getDataType()) {
+            if (!newChild.getDataType().equals(child.getDataType())) {
                 newChildren.add(newChild.castTo(child.getDataType()));
             } else {
                 newChildren.add(newChild);

From 951da11c2b7b7710e63f2b8a6a88f7318948ebed Mon Sep 17 00:00:00 2001
From: LiBinfeng <1204975323@qq.com>
Date: Thu, 19 Sep 2024 11:09:06 +0800
Subject: [PATCH 3/3] fix p0 problem

---
 .../rules/expression/rules/FoldConstantRuleOnBE.java       | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java
index b237a3d6c5eed6..810d281ac579ac 100644
--- a/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java
+++ b/fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rules/FoldConstantRuleOnBE.java
@@ -177,7 +177,12 @@ private static Expression replace(
                 hasNewChildren = true;
             }
             if (!newChild.getDataType().equals(child.getDataType())) {
-                newChildren.add(newChild.castTo(child.getDataType()));
+                try {
+                    newChildren.add(newChild.castTo(child.getDataType()));
+                } catch (Exception e) {
+                    LOG.warn("expression of type {} cast to {} failed. ", newChild.getDataType(), child.getDataType());
+                    newChildren.add(newChild);
+                }
             } else {
                 newChildren.add(newChild);
             }