From 16a60b0fe1e0f6a3af92524cf9fa21af123b290d Mon Sep 17 00:00:00 2001
From: Lloyd-Pottiger <60744015+Lloyd-Pottiger@users.noreply.github.com>
Date: Sat, 25 Mar 2023 16:26:43 +0800
Subject: [PATCH] Storage: should seek before read (#7161)

close pingcap/tidb#42555
---
 dbms/src/Flash/Coprocessor/TiDBTableScan.cpp  |  2 ++
 .../Storages/DeltaMerge/File/DMFileReader.cpp |  7 +++++-
 .../Storages/DeltaMerge/File/DMFileReader.h   |  3 +++
 .../LateMaterializationBlockInputStream.cpp   | 24 +++++++++++++++++--
 4 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/dbms/src/Flash/Coprocessor/TiDBTableScan.cpp b/dbms/src/Flash/Coprocessor/TiDBTableScan.cpp
index 68ef961c471..a5aa5ded6bc 100644
--- a/dbms/src/Flash/Coprocessor/TiDBTableScan.cpp
+++ b/dbms/src/Flash/Coprocessor/TiDBTableScan.cpp
@@ -70,6 +70,8 @@ void TiDBTableScan::constructTableScanForRemoteRead(tipb::TableScan * tipb_table
         tipb_table_scan->set_table_id(table_id);
         for (const auto & column : partition_table_scan.columns())
             *tipb_table_scan->add_columns() = column;
+        for (const auto & filter : partition_table_scan.pushed_down_filter_conditions())
+            *tipb_table_scan->add_pushed_down_filter_conditions() = filter;
         tipb_table_scan->set_desc(partition_table_scan.desc());
         for (auto id : partition_table_scan.primary_column_ids())
             tipb_table_scan->add_primary_column_ids(id);
diff --git a/dbms/src/Storages/DeltaMerge/File/DMFileReader.cpp b/dbms/src/Storages/DeltaMerge/File/DMFileReader.cpp
index 5b4ae4539a8..0bd8787bf72 100644
--- a/dbms/src/Storages/DeltaMerge/File/DMFileReader.cpp
+++ b/dbms/src/Storages/DeltaMerge/File/DMFileReader.cpp
@@ -295,6 +295,7 @@ size_t DMFileReader::skipNextBlock()
 
     scan_context->total_dmfile_skipped_rows += read_rows;
     next_row_offset += read_rows;
+    last_read_skipped = true;
     return read_rows;
 }
 
@@ -396,6 +397,8 @@ Block DMFileReader::readWithFilter(const IColumn::Filter & filter)
     // merge blocks
     Block res = vstackBlocks(std::move(blocks));
     res.setStartOffset(start_row_offset);
+
+    last_read_skipped = false;
     return res;
 }
 
@@ -639,6 +642,8 @@ Block DMFileReader::read()
             e.rethrow();
         }
     }
+
+    last_read_skipped = false;
     return res;
 }
 
@@ -654,7 +659,7 @@ void DMFileReader::readFromDisk(
     if (auto iter = column_streams.find(stream_name); iter != column_streams.end())
     {
         auto & top_stream = iter->second;
-        bool should_seek = force_seek || shouldSeek(start_pack_id) || skip_packs > 0;
+        bool should_seek = force_seek || shouldSeek(start_pack_id) || skip_packs > 0 || last_read_skipped;
 
         auto data_type = dmfile->getColumnStat(column_define.id).type;
         data_type->deserializeBinaryBulkWithMultipleStreams( //
diff --git a/dbms/src/Storages/DeltaMerge/File/DMFileReader.h b/dbms/src/Storages/DeltaMerge/File/DMFileReader.h
index 55924510964..09a31790cb1 100644
--- a/dbms/src/Storages/DeltaMerge/File/DMFileReader.h
+++ b/dbms/src/Storages/DeltaMerge/File/DMFileReader.h
@@ -180,6 +180,9 @@ class DMFileReader
 
     std::unique_ptr<ColumnSharingCacheMap> col_data_cache{};
     std::unordered_map<ColId, bool> last_read_from_cache{};
+
+    /// call skipNextBlock() before read()
+    bool last_read_skipped{false};
 };
 
 } // namespace DM
diff --git a/dbms/src/Storages/DeltaMerge/LateMaterializationBlockInputStream.cpp b/dbms/src/Storages/DeltaMerge/LateMaterializationBlockInputStream.cpp
index 270b92ca15f..f9f9ae8dc1a 100644
--- a/dbms/src/Storages/DeltaMerge/LateMaterializationBlockInputStream.cpp
+++ b/dbms/src/Storages/DeltaMerge/LateMaterializationBlockInputStream.cpp
@@ -55,7 +55,26 @@ Block LateMaterializationBlockInputStream::readImpl()
         // If filter is nullptr, it means that these push down filters are always true.
         if (!filter)
         {
-            Block rest_column_block = rest_column_stream->read();
+            IColumn::Filter col_filter;
+            col_filter.resize(filter_column_block.rows());
+            Block rest_column_block;
+            if (bitmap_filter->get(col_filter, filter_column_block.startOffset(), filter_column_block.rows()))
+            {
+                rest_column_block = rest_column_stream->read();
+            }
+            else
+            {
+                rest_column_block = rest_column_stream->read();
+                size_t passed_count = countBytesInFilter(col_filter);
+                for (auto & col : rest_column_block)
+                {
+                    col.column = col.column->filter(col_filter, passed_count);
+                }
+                for (auto & col : filter_column_block)
+                {
+                    col.column = col.column->filter(col_filter, passed_count);
+                }
+            }
             return hstackBlocks({std::move(filter_column_block), std::move(rest_column_block)}, header);
         }
 
@@ -66,7 +85,7 @@ Block LateMaterializationBlockInputStream::readImpl()
         if (size_t passed_count = countBytesInFilter(*filter); passed_count == 0)
         {
             // if all rows are filtered, skip the next block of rest_column_stream
-            if (rest_column_stream->skipNextBlock() == 0)
+            if (size_t skipped_rows = rest_column_stream->skipNextBlock(); skipped_rows == 0)
             {
                 // if we fail to skip, we need to call read() of rest_column_stream, but ignore the result
                 // NOTE: skipNextBlock() return 0 only if failed to skip or meets the end of stream,
@@ -77,6 +96,7 @@ Block LateMaterializationBlockInputStream::readImpl()
             }
             else
             {
+                RUNTIME_CHECK(skipped_rows == rows);
                 LOG_DEBUG(log, "Late materialization skip read block at start_offset: {}, rows: {}", filter_column_block.startOffset(), filter_column_block.rows());
             }
         }