fix(p3): fix insert, delete executor comments (#448)

Fix insert, delete executor comments

Author: yliang412

src/include/execution/executors/delete_executor.h

@@ -42,13 +42,13 @@ class DeleteExecutor : public AbstractExecutor {
   void Init() override;
 
   /**
-   * Yield the next tuple from the delete.
-   * @param[out] tuple The next tuple produced by the update
-   * @param[out] rid The next tuple RID produced by the update
-   * @return `false` unconditionally (throw to indicate failure)
+   * Yield the number of rows deleted from the table.
+   * @param[out] tuple The integer tuple indicating the number of rows deleted from the table
+   * @param[out] rid The next tuple RID produced by the update (ignore, not used)
+   * @return `true` if a tuple was produced, `false` if there are no more tuples
    *
    * NOTE: DeleteExecutor::Next() does not use the `tuple` out-parameter.
-   * NOTE: DeleteExecutor::Next() does not use the `rid` out-parameter.
+   * NOTE: DeleteExecutor::Next() returns true with the number of deleted rows produced only once
    */
   auto Next([[maybe_unused]] Tuple *tuple, RID *rid) -> bool override;
 

src/include/execution/executors/insert_executor.h

@@ -24,17 +24,15 @@ namespace bustub {
 
 /**
  * InsertExecutor executes an insert on a table.
- *
- * Unlike UPDATE and DELETE, inserted values may either be
- * embedded in the plan itself or be pulled from a child executor.
+ * Inserted values are always pulled from a child executor.
  */
 class InsertExecutor : public AbstractExecutor {
  public:
   /**
    * Construct a new InsertExecutor instance.
    * @param exec_ctx The executor context
    * @param plan The insert plan to be executed
-   * @param child_executor The child executor from which inserted tuples are pulled (may be `nullptr`)
+   * @param child_executor The child executor from which inserted tuples are pulled
    */
   InsertExecutor(ExecutorContext *exec_ctx, const InsertPlanNode *plan,
                  std::unique_ptr<AbstractExecutor> &&child_executor);
@@ -43,13 +41,13 @@ class InsertExecutor : public AbstractExecutor {
   void Init() override;
 
   /**
-   * Yield the next tuple from the insert.
-   * @param[out] tuple The next tuple produced by the insert
-   * @param[out] rid The next tuple RID produced by the insert
+   * Yield the number of rows inserted into the table.
+   * @param[out] tuple The integer tuple indicating the number of rows inserted into the table
+   * @param[out] rid The next tuple RID produced by the insert (ignore, not used)
    * @return `true` if a tuple was produced, `false` if there are no more tuples
    *
-   * NOTE: InsertExecutor::Next() does not use the `tuple` out-parameter.
    * NOTE: InsertExecutor::Next() does not use the `rid` out-parameter.
+   * NOTE: InsertExecutor::Next() returns true with number of inserted rows produced only once
    */
   auto Next([[maybe_unused]] Tuple *tuple, RID *rid) -> bool override;
 

src/include/execution/plans/insert_plan.h

@@ -25,8 +25,7 @@ namespace bustub {
 /**
  * The InsertPlanNode identifies a table into which tuples are inserted.
  *
- * The values to be inserted are either embedded into the InsertPlanNode
- * itself, i.e. a "raw insert", or will come from the child of the node.
+ * The values to be inserted will come from the child of the node.
  *
  * NOTE: To simplify the assignment, InsertPlanNode has at most one child.
  */