Add comment for _prunedSerialNum.

1 files changed, 1 insertions, 0 deletions

diff --git a/searchcore/src/vespa/searchcore/proton/server/feedhandler.h b/searchcore/src/vespa/searchcore/proton/server/feedhandler.h
index 88bd818bf32..eed7367d432 100644
--- a/searchcore/src/vespa/searchcore/proton/server/feedhandler.h
+++ b/searchcore/src/vespa/searchcore/proton/server/feedhandler.h
@@ -77,6 +77,7 @@ private:
     TlsReplayProgress::UP                  _tlsReplayProgress;
     // the serial num of the last feed operation processed by feed handler.
     SerialNum                              _serialNum;
+    // the serial num considered to be fully procssessed and flushed to stable storage. Used to prune transaction log.
     SerialNum                              _prunedSerialNum;
     // the serial num of the last feed operation in the transaction log at startup before replay
     SerialNum                              _replay_end_serial_num;