Resolved memory leak issue with label DYN_SAMPLE_CTX.

src/sql/engine/px/datahub/components/ob_dh_sample.cpp

@@ -103,6 +103,9 @@ OB_DEF_DESERIALIZE(ObDynamicSamplePieceMsg)
           } else if (OB_FAIL(row_stores_.push_back(tmp_store))) {
             LOG_WARN("push back datum store failed", K(ret), K(i));
           }
+          if (OB_FAIL(ret) && nullptr != tmp_store) {
+            tmp_store->~ObChunkDatumStore();
+          }
         }
       }
     }

src/sql/engine/px/exchange/ob_px_dist_transmit_op.cpp

@@ -654,6 +654,9 @@ int ObPxDistTransmitSpec::register_to_datahub(ObExecContext &ctx) const
                   get_piece_sample_msg().row_stores_.push_back(sample_store))) {
               LOG_WARN("fail to push back sample store", K(ret));
             }
+            if (OB_FAIL(ret) && nullptr != sample_store) {
+              sample_store->~ObChunkDatumStore();
+            }
           }
         }
       }