MDEV-15242 Poor RBR update performance with partitioned tables

Observed and described partitioned engine execution time difference between master and slave was caused by excessive invocation of base_engine::rnd_init which was done also for partitions uninvolved into Rows-event operation. The bug's slave slowdown therefore scales with the number of partitions. Fixed with applying an upstream patch. References: ---------- https://bugs.mysql.com/bug.php?id=73648 Bug#25687813 REPLICATION REGRESSION WITH RBR AND PARTITIONED TABLES

Author: andrelkin

sql/ha_partition.cc

@@ -5090,7 +5090,8 @@ int ha_partition::rnd_pos_by_record(uchar *record)
  if (unlikely(get_part_for_delete(record, m_rec0, m_part_info, &m_last_part)))
  DBUG_RETURN(1);
 
- DBUG_RETURN(handler::rnd_pos_by_record(record));
+ int err= m_file[m_last_part]->rnd_pos_by_record(record);
+ DBUG_RETURN(err);
 }
 
 

sql/handler.h

@@ -3042,9 +3042,17 @@ class handler :public Sql_alloc
  */
  virtual int rnd_pos_by_record(uchar *record)
  {
+ int error;
  DBUG_ASSERT(table_flags() & HA_PRIMARY_KEY_REQUIRED_FOR_POSITION);
+
+ error = ha_rnd_init(false);
+ if (error != 0)
+ return error;
+
  position(record);
- return rnd_pos(record, ref);
+ error = ha_rnd_pos(record, ref);
+ ha_rnd_end();
+ return error;
  }
  virtual int read_first_row(uchar *buf, uint primary_key);
 public:

sql/log_event.cc

@@ -12135,10 +12135,6 @@ int Rows_log_event::find_row(rpl_group_info *rgi)
  int error;
  DBUG_PRINT("info",("locating record using primary key (position)"));
 
- if (!table->file->inited &&
- (error= table->file->ha_rnd_init_with_error(0)))
- DBUG_RETURN(error);
-
  error= table->file->ha_rnd_pos_by_record(table->record[0]);
  if (error)
  {