cleanup: cache the result of Rows_log_event::find_key()

sql/log_event_server.cc

@@ -7105,12 +7105,17 @@ static bool record_compare(TABLE *table, bool vers_from_plain= false)
 */
 int Rows_log_event::find_key()
 {
-  uint i, best_key_nr, last_part;
-  KEY *key, *UNINIT_VAR(best_key);
+  DBUG_ASSERT(m_table);
+  RPL_TABLE_LIST *tl= (RPL_TABLE_LIST*)m_table->pos_in_table_list;
+  uint i, best_key_nr;
+  KEY *key;
   ulong UNINIT_VAR(best_rec_per_key), tmp;
   DBUG_ENTER("Rows_log_event::find_key");
-  DBUG_ASSERT(m_table);
 
+  if ((best_key_nr= tl->cached_key_nr) != ~0U)
+    DBUG_ASSERT(best_key_nr <= MAX_KEY); // use the cached value
+  else
+  {
     best_key_nr= MAX_KEY;
 
     /*
@@ -7130,14 +7135,13 @@ int Rows_log_event::find_key()
       if ((key->flags & (HA_NOSAME | HA_NULL_PART_KEY)) == HA_NOSAME)
       {
         best_key_nr= i;
-      best_key= key;
         break;
       }
       /*
         We can only use a non-unique key if it allows range scans (ie. skip
         FULLTEXT indexes and such).
       */
-    last_part= key->user_defined_key_parts - 1;
+      uint last_part= key->user_defined_key_parts - 1;
       DBUG_PRINT("info", ("Index %s rec_per_key[%u]= %lu",
                           key->name.str, last_part, key->rec_per_key[last_part]));
       if (!(m_table->file->index_flags(i, last_part, 1) & HA_READ_NEXT))
@@ -7147,25 +7151,25 @@ int Rows_log_event::find_key()
       if (best_key_nr == MAX_KEY || (tmp > 0 && tmp < best_rec_per_key))
       {
         best_key_nr= i;
-      best_key= key;
         best_rec_per_key= tmp;
       }
     }
+    tl->cached_key_nr= best_key_nr;
+  }
 
+  m_key_nr= best_key_nr;
   if (best_key_nr == MAX_KEY)
-  {
     m_key_info= NULL;
-    DBUG_RETURN(0);
-  }
-
+  else
+  {
+    m_key_info= m_table->key_info + best_key_nr;
     // Allocate buffer for key searches
-  m_key= (uchar *) my_malloc(PSI_INSTRUMENT_ME, best_key->key_length, MYF(MY_WME));
+    m_key= (uchar *) my_malloc(PSI_INSTRUMENT_ME, m_key_info->key_length, MYF(MY_WME));
     if (m_key == NULL)
       DBUG_RETURN(HA_ERR_OUT_OF_MEM);
-  m_key_info= best_key;
-  m_key_nr= best_key_nr;
+  }
 
-  DBUG_RETURN(0);;
+  DBUG_RETURN(0);
 }
 
 

sql/rpl_utility.h

@@ -249,24 +249,24 @@ class table_def
    Extend the normal table list with a few new fields needed by the
    slave thread, but nowhere else.
  */
-struct RPL_TABLE_LIST
-  : public TABLE_LIST
+struct RPL_TABLE_LIST : public TABLE_LIST
 {
-  bool m_tabledef_valid;
-  bool master_had_triggers;
   table_def m_tabledef;
   TABLE *m_conv_table;
   const Copy_field *m_online_alter_copy_fields;
   const Copy_field *m_online_alter_copy_fields_end;
+  uint cached_key_nr;                  // [0..MAX_KEY] if set, ~0U if unset
+  bool m_tabledef_valid;
+  bool master_had_triggers;
 
   RPL_TABLE_LIST(const LEX_CSTRING *db_arg, const LEX_CSTRING *table_name_arg,
                  thr_lock_type thr_lock_type,
                  table_def &&tabledef, bool master_had_trigers)
     : TABLE_LIST(db_arg, table_name_arg, NULL, thr_lock_type),
-      m_tabledef_valid(true), master_had_triggers(master_had_trigers),
       m_tabledef(std::move(tabledef)), m_conv_table(NULL),
-      m_online_alter_copy_fields(NULL),
-      m_online_alter_copy_fields_end(NULL)
+      m_online_alter_copy_fields(NULL), m_online_alter_copy_fields_end(NULL),
+      cached_key_nr(~0U), m_tabledef_valid(true),
+      master_had_triggers(master_had_trigers)
   {}
 
   RPL_TABLE_LIST(TABLE *table, thr_lock_type lock_type, TABLE *conv_table,
@@ -274,12 +274,10 @@ struct RPL_TABLE_LIST
                  const Copy_field online_alter_copy_fields[],
                  const Copy_field *online_alter_copy_fields_end)
     : TABLE_LIST(table, lock_type),
-       m_tabledef_valid(true),
-       master_had_triggers(false),
-       m_tabledef(std::move(tabledef)),
-       m_conv_table(conv_table),
+      m_tabledef(std::move(tabledef)), m_conv_table(conv_table),
       m_online_alter_copy_fields(online_alter_copy_fields),
-       m_online_alter_copy_fields_end(online_alter_copy_fields_end)
+      m_online_alter_copy_fields_end(online_alter_copy_fields_end),
+      cached_key_nr(~0U), m_tabledef_valid(true), master_had_triggers(false)
   {}
 };