[CP] fix memtable reference leaks due to not deconstruct lob cursor

src/sql/engine/expr/ob_expr_json_func_helper.cpp

@@ -331,6 +331,9 @@ int ObJsonExprHelper::get_json_for_partial_update(
     } else {
       j_base = delta_lob.get_json_bin();
     }
+    if (OB_FAIL(ret)) {
+      delta_lob.reset();
+    }
   } else if (! locator.is_persist_lob() || locator.is_inrow()) {
     ret = OB_ERR_UNEXPECTED;
     LOG_WARN("persis lob or no-delta inrow lob locator not support", KR(ret), K(locator));
@@ -364,6 +367,17 @@ int ObJsonExprHelper::get_json_for_partial_update(
     ret = OB_ERR_UNEXPECTED;
     LOG_WARN("get j_base is null", KR(ret), K(locator));
   }
+
+  if (OB_FAIL(ret)) {
+    if (OB_NOT_NULL(j_base)) {
+      j_base->reset();
+      j_base = nullptr;
+    }
+    if (OB_NOT_NULL(cursor)) {
+      cursor->reset();
+      cursor = nullptr;
+    }
+  }
   return ret;
 }
 
@@ -2615,6 +2629,26 @@ int ObJsonDeltaLob::init(ObIAllocator *allocator, ObLobLocatorV2 locator, int64_
   return ret;
 }
 
+void ObJsonDeltaLob::reset()
+{
+  if (OB_NOT_NULL(j_base_)) {
+    j_base_->reset();
+    j_base_ = nullptr;
+  }
+  if (OB_NOT_NULL(update_ctx_)) {
+    update_ctx_->~ObJsonBinUpdateCtx();
+    update_ctx_ = nullptr;
+  }
+  if (OB_NOT_NULL(cursor_)) {
+    cursor_->~ObLobCursor();
+    cursor_ = nullptr;
+  }
+  if (OB_NOT_NULL(partial_data_)) {
+    partial_data_->~ObLobPartialData();
+    partial_data_ = nullptr;
+  }
+}
+
 int64_t ObJsonDeltaLob::get_lob_diff_serialize_size() const
 {
   int64_t len = 0;

src/sql/engine/expr/ob_expr_json_func_helper.h

@@ -490,6 +490,7 @@ public:
 
   int init(ObJsonBin *j_bin);
   int init(ObIAllocator *allocator, ObLobLocatorV2 locator, int64_t query_timeout_ts);
+  void reset();
 
   int64_t get_partial_data_serialize_size() const;
   int64_t get_lob_diff_serialize_size() const;