-- already approved; it would be nice if it goes into 3.23.57 --

Fix for bug 254 : the first Start_log_event after server startup will
have created=now(), whereas the next ones (FLUSH LOGS, auto rotation)
will have created=0. Before this, it was always now().
This way, slaves >=4.0.14 will know when they must
drop stale temp tables or not. The next task is now modify 4.0.14 to
implement this.

sql/log.cc

@@ -157,7 +157,7 @@ void MYSQL_LOG::close_index()
 }
 
 void MYSQL_LOG::open(const char *log_name, enum_log_type log_type_arg,
-		     const char *new_name)
+		     const char *new_name, bool null_created)
 {
   MY_STAT tmp_stat;
   char buff[512];
@@ -230,8 +230,10 @@ void MYSQL_LOG::open(const char *log_name, enum_log_type log_type_arg,
     if ((do_magic && my_b_write(&log_file, (byte*) BINLOG_MAGIC, 4)) ||
 	open_index(O_APPEND | O_RDWR | O_CREAT))
       goto err;
-    Start_log_event s;
     bool error;
+    Start_log_event s;
+    if (null_created)
+      s.created= 0;
     s.write(&log_file);
     flush_io_cache(&log_file);
     pthread_mutex_lock(&LOCK_index);
@@ -548,7 +550,15 @@ void MYSQL_LOG::new_file(bool inside_mutex)
     strmov(new_name, old_name);		// Reopen old file name
   name=0;
   close();
-  open(old_name, log_type, new_name);
+  /* 
+     new_file() is only used for rotation (in FLUSH LOGS or because size >
+     max_binlog_size). 
+     If this is a binary log, the Start_log_event at the beginning of
+     the new file should have created=0 (to distinguish with the Start_log_event
+     written at server startup, which should trigger temp tables deletion on
+     >=4.0.14 slaves).
+  */ 
+  open(old_name, log_type, new_name, 1);
   my_free(old_name,MYF(0));
   last_time=query_start=0;
   write_error=0;

sql/log_event.h

@@ -327,6 +327,15 @@ extern char server_version[SERVER_VERSION_LENGTH];
 class Start_log_event: public Log_event
 {
 public:
+  /* 
+     If this event is at the start of the first binary log since server startup
+     'created' should be the timestamp when the event (and the binary log) was
+     created. 
+     In the other case (i.e. this event is at the start of a binary log created
+     by FLUSH LOGS or automatic rotation), 'created' should be 0.
+     This "trick" is used by MySQL >=4.0.14 slaves to know if they must drop the
+     stale temporary tables or not.
+  */
   time_t created;
   uint16 binlog_version;
   char server_version[50];

sql/sql_class.h

@@ -73,7 +73,7 @@ public:
   void set_index_file_name(const char* index_file_name = 0);
   void init(enum_log_type log_type_arg);
   void open(const char *log_name,enum_log_type log_type,
-	    const char *new_name=0);
+	    const char *new_name=0, bool null_created= 0);
   void new_file(bool inside_mutex = 0);
   bool open_index(int options);
   void close_index();