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

Fix insert, delete executor comments

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.
  */