bzr commit into mysql-5.1 branch (hezx:2666) Bug#35843

[He Zhenxing]

#At file:///media/sda3/work/mysql/bzrwork/b35843/5.1-rpl/

 2666 He Zhenxing	2008-09-09
      BUG#35843 Slow replication slave when using partitioned myisam table
      
      In order to improve the performance when replicating to partitioned
      myisam tables with row-based format, a new function 'estimate_rows'
      is added for Rows_log_event to estimate the number of rows of current
      rows log event and use the estimated number to allocate cache memory.
modified:
  sql/log_event.cc
  sql/log_event.h

=== modified file 'sql/log_event.cc'
--- a/sql/log_event.cc	2008-08-06 10:41:27 +0000
+++ b/sql/log_event.cc	2008-09-09 09:20:46 +0000
@@ -7439,8 +7439,28 @@ Write_rows_log_event::Write_rows_log_eve
 #endif
 
 #if !defined(MYSQL_CLIENT) && defined(HAVE_REPLICATION)
+/*
+  Estimate the number of rows of current event.
+*/
+ulong
+Rows_log_event::estimate_rows(Relay_log_info const *rli)
+{
+  const uchar *curr_row_end;
+  MY_BITMAP cols;
+  int const result= ::unpack_row(rli, m_table, m_width, m_curr_row,
+                                 &cols, &curr_row_end, 0);
+  if (curr_row_end > m_rows_end)
+  {
+    my_error(ER_SLAVE_CORRUPT_EVENT, MYF(0));
+    return 0;
+  }
+
+  ulong rows= (m_rows_end - m_curr_row) / (curr_row_end - m_curr_row);
+  return rows;
+}
+
 int 
-Write_rows_log_event::do_before_row_operations(const Slave_reporting_capability *const)
+Write_rows_log_event::do_before_row_operations(const Slave_reporting_capability *const
log)
 {
   int error= 0;
 
@@ -7488,7 +7508,10 @@ Write_rows_log_event::do_before_row_oper
     */
   }
 
-  m_table->file->ha_start_bulk_insert(0);
+  ulong rows= estimate_rows((Relay_log_info const*)log);
+  if (!rows)
+    return 1;
+  m_table->file->ha_start_bulk_insert(rows);
   /*
     We need TIMESTAMP_NO_AUTO_SET otherwise ha_write_row() will not use fill
     any TIMESTAMP column with data from the row but instead will use

=== modified file 'sql/log_event.h'
--- a/sql/log_event.h	2008-07-31 06:24:27 +0000
+++ b/sql/log_event.h	2008-09-09 09:20:46 +0000
@@ -3428,6 +3428,16 @@ public:
 
   uint     m_row_count;         /* The number of rows added to the event */
 
+  /**
+    Estimate number of rows included in this Rows_log_event.
+
+    @param rli Relay log info structure
+
+    @retval >0 the number of rows in the event
+    @retval 0 the event is corrupted
+   */
+  ulong estimate_rows(Relay_log_info const *rli);
+
 protected:
   /* 
      The constructors are protected since you're supposed to inherit