From d70c17bdc006421af0b6af3fde7ea81db68fe4c9 Mon Sep 17 00:00:00 2001
From: Pxl <xl@selectdb.com>
Date: Mon, 23 Dec 2024 13:54:12 +0800
Subject: [PATCH] [Improvement](scan) use loop to instead recursion on
 Level1Iterator::_normal_next #38005 (#45767)

pick from  #38005
---
 be/src/vec/olap/vcollect_iterator.cpp | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/be/src/vec/olap/vcollect_iterator.cpp b/be/src/vec/olap/vcollect_iterator.cpp
index a020119924df49..d785ccf4ebc107 100644
--- a/be/src/vec/olap/vcollect_iterator.cpp
+++ b/be/src/vec/olap/vcollect_iterator.cpp
@@ -865,20 +865,20 @@ Status VCollectIterator::Level1Iterator::_merge_next(Block* block) {
 Status VCollectIterator::Level1Iterator::_normal_next(Block* block) {
     SCOPED_RAW_TIMER(&_reader->_stats.collect_iterator_normal_next_timer);
     auto res = _cur_child->next(block);
+
+    while (res.is<END_OF_FILE>() && !_children.empty()) {
+        _cur_child = std::move(*(_children.begin()));
+        _children.pop_front();
+        // clear TEMP columns to avoid column align problem
+        block->erase_tmp_columns();
+        res = _cur_child->next(block);
+    }
+
     if (LIKELY(res.ok())) {
         return Status::OK();
     } else if (res.is<END_OF_FILE>()) {
-        // current child has been read, to read next
-        if (!_children.empty()) {
-            _cur_child = std::move(*(_children.begin()));
-            _children.pop_front();
-            // clear TEMP columns to avoid column align problem
-            block->erase_tmp_columns();
-            return _normal_next(block);
-        } else {
-            _cur_child.reset();
-            return Status::Error<END_OF_FILE>("");
-        }
+        _cur_child.reset();
+        return Status::Error<END_OF_FILE>("");
     } else {
         _cur_child.reset();
         LOG(WARNING) << "failed to get next from child, res=" << res;