Update batch_redo.h

src/include/access/extreme_rto/batch_redo.h

@@ -26,6 +26,8 @@
 #ifndef BATCH_REDO_H
 #define BATCH_REDO_H
 
+/*This header file is used for replay after the failure of multi-batch database.*/
+
 #include "c.h"
 #include "storage/buf/block.h"
 #include "storage/smgr/relfilenode.h"
@@ -64,6 +66,7 @@ typedef struct redoitemhashentry {
     XLogRecParseState *tail;
     int redoItemNum;
 } RedoItemHashEntry;
+/*Provide operations for multiple threads*/
 
 extern void PRPrintRedoItemHashTab(HTAB *redoItemHash);
 extern HTAB *PRRedoItemHashInitialize(MemoryContext context);