From 6819cdffe17671a25a410f26bbc59cdabaf0a867 Mon Sep 17 00:00:00 2001
From: Alexander Kotov <akotov@ydb.tech>
Date: Wed, 5 Feb 2025 13:42:49 +0300
Subject: [PATCH] [+] commments

---
 ydb/core/persqueue/partition.cpp       | 1 +
 ydb/core/persqueue/partition_init.cpp  | 3 +++
 ydb/core/persqueue/partition_write.cpp | 1 +
 3 files changed, 5 insertions(+)

diff --git a/ydb/core/persqueue/partition.cpp b/ydb/core/persqueue/partition.cpp
index af69c0f5e992..8380dfb89970 100644
--- a/ydb/core/persqueue/partition.cpp
+++ b/ydb/core/persqueue/partition.cpp
@@ -3402,6 +3402,7 @@ void TPartition::ScheduleUpdateAvailableSize(const TActorContext& ctx) {
 void TPartition::ClearOldHead(const ui64 offset, const ui16 partNo, TEvKeyValue::TEvRequest* request) {
     for (auto it = HeadKeys.rbegin(); it != HeadKeys.rend(); ++it) {
         if (it->Key.GetOffset() > offset || it->Key.GetOffset() == offset && it->Key.GetPartNo() >= partNo) {
+            // The repackaged blocks will be deleted after writing.
             DefferedKeysForDeletion.push_back(std::move(it->BlobKeyToken));
 
             Y_UNUSED(request);
diff --git a/ydb/core/persqueue/partition_init.cpp b/ydb/core/persqueue/partition_init.cpp
index 9d15671886c0..31117feb7ccf 100644
--- a/ydb/core/persqueue/partition_init.cpp
+++ b/ydb/core/persqueue/partition_init.cpp
@@ -575,6 +575,9 @@ void TInitDataRangeStep::FillBlobsMetaData(const NKikimrClient::TKeyValueRespons
     auto& gapSize = Partition()->GapSize;
     auto& bodySize = Partition()->BodySize;
 
+    // If there are multiple keys for a message, then only the key that contains more messages remains.
+    //
+    // Extra keys will be added to the queue for deletion.
     const auto actualKeys = FilterBlobsMetaData(range,
                                                 PartitionId());
 
diff --git a/ydb/core/persqueue/partition_write.cpp b/ydb/core/persqueue/partition_write.cpp
index c38533ff605f..fce4a2360674 100644
--- a/ydb/core/persqueue/partition_write.cpp
+++ b/ydb/core/persqueue/partition_write.cpp
@@ -388,6 +388,7 @@ void TPartition::SyncMemoryStateWithKVState(const TActorContext& ctx) {
         HeadKeys.clear();
     }
 
+    // New blocks have been recorded. You can now delete the keys of the repackaged blocks.
     DefferedKeysForDeletion.clear();
 
     if (NewHeadKey.Size > 0) {