diff --git a/src/gausskernel/optimizer/commands/tablecmds.cpp b/src/gausskernel/optimizer/commands/tablecmds.cpp
index e303a4d1b..a52496dc7 100644
--- a/src/gausskernel/optimizer/commands/tablecmds.cpp
+++ b/src/gausskernel/optimizer/commands/tablecmds.cpp
@@ -6993,7 +6993,7 @@ static LOCKMODE GetPartitionLockLevel(AlterTableType subType)
         case AT_DropSubPartition:
         case AT_ExchangePartition:
         case AT_TruncatePartition:
-            cmdLockMode = RowExclusiveLock;
+            cmdLockMode = ShareUpdateExclusiveLock;
             break;
         default:
             cmdLockMode = AccessExclusiveLock;
diff --git a/src/gausskernel/optimizer/util/plancat.cpp b/src/gausskernel/optimizer/util/plancat.cpp
index f04251166..1fe7d0151 100755
--- a/src/gausskernel/optimizer/util/plancat.cpp
+++ b/src/gausskernel/optimizer/util/plancat.cpp
@@ -316,7 +316,7 @@ static void acquireSamplesForPartitionedRelation(
                     continue;
                 }
 
-                part = partitionOpen(relation, partitionOid, lmode);
+                part = partitionOpen(relation, partitionOid, NoLock);
                 currentPartPages = PartitionGetNumberOfBlocksInFork(relation, part, MAIN_FORKNUM, true);
                 partitionClose(relation, part, lmode);