From 6f484734c2b7c8f1c2aaa365461772d560dd0c60 Mon Sep 17 00:00:00 2001
From: Anton Popov <anton@clickhouse.com>
Date: Wed, 1 May 2024 11:34:59 +0000
Subject: [PATCH] fix reading in general case

---
 src/Storages/MergeTree/MergeTreeIOSettings.h         |  2 ++
 src/Storages/MergeTree/MergeTreeReaderWide.cpp       | 10 ++++++----
 src/Storages/MergeTree/MergeTreeReaderWide.h         |  2 +-
 src/Storages/MergeTree/MergeTreeSequentialSource.cpp |  1 +
 4 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/Storages/MergeTree/MergeTreeIOSettings.h b/src/Storages/MergeTree/MergeTreeIOSettings.h
index feeb1808a6f..12a83703148 100644
--- a/src/Storages/MergeTree/MergeTreeIOSettings.h
+++ b/src/Storages/MergeTree/MergeTreeIOSettings.h
@@ -44,6 +44,8 @@ struct MergeTreeReaderSettings
     bool enable_multiple_prewhere_read_steps = false;
     /// If true, try to lower size of read buffer according to granule size and compressed block size.
     bool adjust_read_buffer_size = true;
+    /// If true, it's allowed to read the whole part without reading marks.
+    bool can_read_part_without_marks = false;
 };
 
 struct MergeTreeWriterSettings
diff --git a/src/Storages/MergeTree/MergeTreeReaderWide.cpp b/src/Storages/MergeTree/MergeTreeReaderWide.cpp
index d398668d5c8..59feb4dda19 100644
--- a/src/Storages/MergeTree/MergeTreeReaderWide.cpp
+++ b/src/Storages/MergeTree/MergeTreeReaderWide.cpp
@@ -43,7 +43,9 @@ MergeTreeReaderWide::MergeTreeReaderWide(
         mark_ranges_,
         settings_,
         avg_value_size_hints_)
-    , read_whole_part(all_mark_ranges.isOneRangeForWholePart(data_part_info_for_read->getMarksCount()))
+    , read_without_marks(
+        settings.can_read_part_without_marks
+        && all_mark_ranges.isOneRangeForWholePart(data_part_info_for_read->getMarksCount()))
 {
     try
     {
@@ -254,7 +256,7 @@ void MergeTreeReaderWide::addStreams(
                 std::move(marks_loader), profile_callback, clock_type);
         };
 
-        if (read_whole_part)
+        if (read_without_marks)
         {
             streams.emplace(*stream_name, create_stream.operator()<MergeTreeReaderStreamSingleColumnWholePart>());
         }
@@ -340,7 +342,7 @@ void MergeTreeReaderWide::prefetchForColumn(
 
         if (stream_name && !prefetched_streams.contains(*stream_name))
         {
-            bool seek_to_mark = !continue_reading && !read_whole_part;
+            bool seek_to_mark = !continue_reading && !read_without_marks;
 
             if (ReadBuffer * buf = getStream(false, substream_path, data_part_info_for_read->getChecksums(), streams, name_and_type, from_mark, seek_to_mark, current_task_last_mark, cache))
             {
@@ -365,7 +367,7 @@ void MergeTreeReaderWide::readData(
 
     deserialize_settings.getter = [&](const ISerialization::SubstreamPath & substream_path)
     {
-        bool seek_to_mark = !was_prefetched && !continue_reading && !read_whole_part;
+        bool seek_to_mark = !was_prefetched && !continue_reading && !read_without_marks;
 
         return getStream(
             /* seek_to_start = */false, substream_path,
diff --git a/src/Storages/MergeTree/MergeTreeReaderWide.h b/src/Storages/MergeTree/MergeTreeReaderWide.h
index 7ffe565d262..9f6bdd79b00 100644
--- a/src/Storages/MergeTree/MergeTreeReaderWide.h
+++ b/src/Storages/MergeTree/MergeTreeReaderWide.h
@@ -73,7 +73,7 @@ private:
     std::unordered_map<String, ISerialization::SubstreamsCache> caches;
     std::unordered_set<std::string> prefetched_streams;
     ssize_t prefetched_from_mark = -1;
-    bool read_whole_part = false;
+    bool read_without_marks = false;
 };
 
 }
diff --git a/src/Storages/MergeTree/MergeTreeSequentialSource.cpp b/src/Storages/MergeTree/MergeTreeSequentialSource.cpp
index 47661a3ff93..0939378932b 100644
--- a/src/Storages/MergeTree/MergeTreeSequentialSource.cpp
+++ b/src/Storages/MergeTree/MergeTreeSequentialSource.cpp
@@ -174,6 +174,7 @@ MergeTreeSequentialSource::MergeTreeSequentialSource(
         .read_settings = read_settings,
         .save_marks_in_cache = false,
         .apply_deleted_mask = apply_deleted_mask,
+        .can_read_part_without_marks = true,
     };
 
     if (!mark_ranges)