diff --git a/src/common/backend/utils/mmgr/aset.cpp b/src/common/backend/utils/mmgr/aset.cpp
index 34ad4afaf..ece3f5f34 100644
--- a/src/common/backend/utils/mmgr/aset.cpp
+++ b/src/common/backend/utils/mmgr/aset.cpp
@@ -1603,10 +1603,14 @@ void GenericMemoryAllocator::AllocSetStats(MemoryContext context, int level)
 void AllocSetCheckPointer(void* pointer)
 {
     AllocChunkData* chunk = (AllocChunkData*)(((char*)(pointer)) - ALLOC_CHUNKHDRSZ);
-    AllocMagicData* magic =
-        (AllocMagicData*)(((char*)chunk) + ALLOC_CHUNKHDRSZ + MAXALIGN(chunk->requested_size) - ALLOC_MAGICHDRSZ);
 
-    Assert(magic->aset == chunk->aset && magic->size == chunk->size && magic->posnum == PosmagicNum);
+    /* For opt memory context, we use sentinel instead of magic number to protect memory overflow. */
+    if (!IsOptAllocSetContext(chunk->aset)) {
+        AllocMagicData* magic =
+            (AllocMagicData*)(((char*)chunk) + ALLOC_CHUNKHDRSZ + MAXALIGN(chunk->requested_size) - ALLOC_MAGICHDRSZ);
+
+        Assert(magic->aset == chunk->aset && magic->size == chunk->size && magic->posnum == PosmagicNum);
+    }
 }
 
 /*
diff --git a/src/common/backend/utils/mmgr/opt_aset.cpp b/src/common/backend/utils/mmgr/opt_aset.cpp
index 9073cf6e5..0e79d869d 100644
--- a/src/common/backend/utils/mmgr/opt_aset.cpp
+++ b/src/common/backend/utils/mmgr/opt_aset.cpp
@@ -864,6 +864,8 @@ static void* opt_AllocSetRealloc(MemoryContext context, void* pointer, Size alig
     if (oldsize >= size) {
 #ifdef MEMORY_CONTEXT_CHECKING
         chunk->requested_size = size;
+        if (size < oldsize)
+            set_sentinel(pointer, size);
 #endif
         return pointer;
     }
@@ -914,6 +916,8 @@ static void* opt_AllocSetRealloc(MemoryContext context, void* pointer, Size alig
         chunk->size = chksize;
 #ifdef MEMORY_CONTEXT_CHECKING
         chunk->requested_size = size;
+        if (size < chunk->size)
+            set_sentinel(AllocChunkGetPointer(chunk), size);
 #endif
         return AllocChunkGetPointer(chunk);
     }