fix wrong output bug for group join buffer

src/sql/engine/basic/ob_group_join_buffer.cpp

@@ -333,43 +333,114 @@ int ObGroupJoinBufffer::get_next_left_iter()
   return ret;
 }
 
+int ObGroupJoinBufffer::drain_left()
+{
+  int ret = OB_SUCCESS;
+  bool need_drain = !left_store_group_idx_.empty();
+  const ObChunkDatumStore::StoredRow *row = NULL;
+  // drain old rows from left store
+  for (int64_t i = left_store_read_; OB_SUCC(ret) && need_drain && i < left_store_group_idx_.count(); ++i) {
+    if (above_group_idx_for_read_ != left_store_group_idx_.at(i)) {
+      need_drain = false;
+    } else if (OB_FAIL(left_store_iter_.get_next_row(row))) {
+      ret = (OB_ITER_END == ret) ? OB_ERR_UNEXPECTED : ret;
+      LOG_WARN("get next row failed", KR(ret));
+    } else {
+      ++left_store_read_;
+    }
+  }
+  // discard unread rows from left op
+  if (OB_SUCC(ret) && need_drain && !is_left_end_) {
+    if (!spec_->is_vectorized()) {
+      while (OB_SUCC(ret)) {
+        op_->clear_evaluated_flag();
+        if (!rescan_params_->empty()) {
+          op_->set_pushdown_param_null(*rescan_params_);
+        }
+        ret = left_->get_next_row();
+      }
+      if (OB_ITER_END == ret) {
+        ret = OB_SUCCESS;
+        is_left_end_ = true;
+      } else {
+        LOG_WARN("get next left row failed", KR(ret));
+      }
+    } else {
+      const ObBatchRows *batch_rows = NULL;
+      int64_t max_row_cnt = min(max_group_size_, spec_->max_batch_size_);
+      if (save_last_batch_) {
+        last_batch_.to_exprs(*eval_ctx_);
+        save_last_batch_ = false;
+      }
+      batch_rows = &left_->get_brs();
+      while (OB_SUCC(ret) && !batch_rows->end_) {
+        if (!rescan_params_->empty()) {
+          op_->set_pushdown_param_null(*rescan_params_);
+        }
+        if (OB_FAIL(left_->get_next_batch(max_row_cnt, batch_rows))) {
+          LOG_WARN("get next batch from left failed", KR(ret));
+        }
+      }
+      if (OB_SUCC(ret) && batch_rows->end_) {
+        is_left_end_ = true;
+      }
+      if (OB_SUCC(ret)) {
+        if (!(batch_rows->size_ == 0 && batch_rows->end_)) {
+          last_batch_.from_exprs(*eval_ctx_, batch_rows->skip_, spec_->max_batch_size_);
+          save_last_batch_ = true;
+        }
+        const_cast<ObBatchRows *&>(batch_rows)->end_ = false;
+      }
+    }
+  }
+  return ret;
+}
+
 int ObGroupJoinBufffer::rescan_left()
 {
   int ret = OB_SUCCESS;
   bool need_rescan = false;
-  if (is_multi_level_) {
-    // for multi level group rescan, we only rescan left if
-    // there is a new group of params for left child.
-    // note that if op_ is a child of SPF, param store can be
-    // filled with a new group before we finish processing the
-    // current group. in that case, we need to discard the old
-    // group and switch to the new batch.
-    ObPhysicalPlanCtx *plan_ctx = GET_PHY_PLAN_CTX(*ctx_);
-    for (int64_t i = 0; !need_rescan && i < left_rescan_params_->count(); i++) {
-      int64_t param_idx = left_rescan_params_->at(i).param_idx_;
-      if (plan_ctx->get_param_store().at(param_idx).is_ext_sql_array()) {
-        need_rescan = true;
+  const ObChunkDatumStore::StoredRow *row = NULL;
+  if (OB_SUCC(ret)) {
+    if (is_multi_level_) {
+      // for multi level group rescan, we only rescan left if
+      // there is a new group of params for left child.
+      // note that if op_ is a child of SPF, param store can be
+      // filled with a new group before we finish processing the
+      // current group. in that case, we need to discard the old
+      // group and switch to the new batch.
+      ObPhysicalPlanCtx *plan_ctx = GET_PHY_PLAN_CTX(*ctx_);
+      for (int64_t i = 0; !need_rescan && i < left_rescan_params_->count(); i++) {
+        int64_t param_idx = left_rescan_params_->at(i).param_idx_;
+        if (plan_ctx->get_param_store().at(param_idx).is_ext_sql_array()) {
+          need_rescan = true;
+        }
+      }
+    } else {
+      need_rescan = true;
+    }
+  }
+  if (OB_SUCC(ret)) {
+    if (need_rescan) {
+      if (OB_FAIL(set_above_group_size())) {
+        LOG_WARN("set above group size failed", KR(ret));
+      } else if (OB_FAIL(left_->rescan())) {
+        LOG_WARN("rescan left failed", KR(ret),
+                 K(left_->get_spec().get_id()), K(left_->op_name()));
+      } else {
+        is_left_end_ = false;
+        above_group_idx_for_expand_ = 0;
+        above_group_idx_for_read_ = 0;
+        reset_buffer_state();
+      }
+    } else {
+      if (OB_FAIL(drain_left())) {
+        LOG_WARN("drain left failed", KR(ret));
+      } else {
+        is_left_end_ = false;
+        above_group_idx_for_read_++;
       }
     }
-  } else {
-    need_rescan = true;
-  }
-  if (OB_FAIL(ret)) {
-    // do nothing
-  } else if (need_rescan) {
-    if (OB_FAIL(set_above_group_size())) {
-      LOG_WARN("set above group size failed", KR(ret));
-    } else if (OB_FAIL(left_->rescan())) {
-      LOG_WARN("rescan left failed", KR(ret),
-               K(left_->get_spec().get_id()), K(left_->op_name()));
-    } else {
-      is_left_end_ = false;
-      above_group_idx_for_expand_ = 0;
-      above_group_idx_for_read_ = 0;
-    }
-  } else {
-    is_left_end_ = false;
-    above_group_idx_for_read_++;
   }
   return ret;
 }

src/sql/engine/basic/ob_group_join_buffer.h

@@ -77,6 +77,7 @@ public:
   int has_next_left_row(bool &has_next);
   int init_above_group_params();
   int fill_cur_row_group_param();
+  int drain_left();
   int rescan_left();
   int rescan_right();
   int fill_group_buffer();