[+] comments

Author: Alek5andr-Kotov

ydb/core/persqueue/partition.cpp

@@ -2310,6 +2310,8 @@ void TPartition::CommitWriteOperations(TTransaction& t)
 
     if (!t.WriteInfo->BlobsFromHead.empty()) {
         auto& first = t.WriteInfo->BlobsFromHead.front();
+        // In one operation, a partition can write blocks of several transactions. Some of them can be broken down
+        // into parts. We need to take this division into account.
         NewHead.PartNo += first.GetPartNo();
 
         Parameters->HeadCleared = Parameters->HeadCleared || !t.WriteInfo->BodyKeys.empty();

ydb/public/sdk/cpp/src/client/topic/ut/topic_to_table_ut.cpp

@@ -2916,7 +2916,8 @@ Y_UNIT_TEST_F(Write_Random_Sized_Messages_In_Wide_Transactions, TFixture)
     // The test verifies the simultaneous execution of several transactions. There is a topic
     // with PARTITIONS_COUNT partitions. In each transaction, the test writes to all the partitions.
     // The size of the messages is random. Such that both large blobs in the body and small ones in
-    // the head of the partition are obtained.
+    // the head of the partition are obtained. Message sizes are multiples of 500 KB. This way we
+    // will make sure that when committing transactions, the division into blocks is taken into account.
 
     const size_t PARTITIONS_COUNT = 20;
     const size_t TXS_COUNT = 100;