Fix for Bug#6148. Only rewind read position in binary log when the

slave SQL thread is started.


sql/slave.cc:
  Adding threads to init as parameter to init_master_info.
  Only rewind read position when starting SQL thread.
sql/slave.h:
  Adding threads to init as parameter to init_master_info.
  Only rewind read position when starting SQL thread.
sql/sql_repl.cc:
  Adding threads to init as parameter to init_master_info.
  Only rewind read position when starting SQL thread.
sql/repl_failsafe.cc:
  Adding threads to init as parameter to init_master_info.
  Only rewind read position when starting SQL thread.

1 files changed, 11 insertions, 3 deletions

diff --git a/sql/slave.cc b/sql/slave.cc
index 18e0ec5929f..7e544572755 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -137,7 +137,7 @@ int init_slave()
   }
     
   if (init_master_info(active_mi,master_info_file,relay_log_info_file,
-		       !master_host))
+		       !master_host, (SLAVE_IO | SLAVE_SQL)))
   {
     sql_print_error("Failed to initialize the master info structure");
     goto err;
@@ -1616,7 +1616,8 @@ void clear_last_slave_error(RELAY_LOG_INFO* rli)
 
 int init_master_info(MASTER_INFO* mi, const char* master_info_fname,
 		     const char* slave_info_fname,
-		     bool abort_if_no_master_info_file)
+		     bool abort_if_no_master_info_file,
+		     int thread_mask)
 {
   int fd,error;
   char fname[FN_REFLEN+128];
@@ -1630,8 +1631,15 @@ int init_master_info(MASTER_INFO* mi, const char* master_info_fname,
       last time. If this case pos_in_file would be set and we would
       get a crash when trying to read the signature for the binary
       relay log.
+      
+      We only rewind the read position if we are starting the SQL
+      thread. The handle_slave_sql thread assumes that the read
+      position is at the beginning of the file, and will read the
+      "signature" and then fast-forward to the last position read.
     */
-    my_b_seek(mi->rli.cur_log, (my_off_t) 0);
+    if (thread_mask & SLAVE_SQL) {
+      my_b_seek(mi->rli.cur_log, (my_off_t) 0);
+    }
     DBUG_RETURN(0);
   }