Fixed bug mdev-4019.

The bug could cause a crash when several connections needed
persistent statistics for the same table.

Also added a missing call of set_statistics_for_table() in the code
of the function mysql_update.

1 files changed, 8 insertions, 2 deletions

diff --git a/sql/sql_statistics.cc b/sql/sql_statistics.cc
index 9de5aa080e1..68f26ebf90b 100644
--- a/sql/sql_statistics.cc
+++ b/sql/sql_statistics.cc
@@ -2501,6 +2501,8 @@ int read_statistics_for_table(THD *thd, TABLE *table, TABLE_LIST *stat_tables)
     }
   }
       
+  table->stats_is_read= TRUE;
+
   DBUG_RETURN(0);
 }
 
@@ -2559,6 +2561,8 @@ bool statistics_for_tables_is_needed(THD *thd, TABLE_LIST *tables)
           table_share->stats_cb.stats_can_be_read &&
           !table_share->stats_cb.stats_is_read)
         return TRUE;
+      if (table_share->stats_cb.stats_is_read)
+        tl->table->stats_is_read= TRUE;
     } 
   }
 
@@ -2618,6 +2622,8 @@ int read_statistics_for_tables_if_needed(THD *thd, TABLE_LIST *tables)
         (void) read_statistics_for_table(thd, tl->table, stat_tables);
         table_share->stats_cb.stats_is_read= TRUE;
       }
+      if (table_share->stats_cb.stats_is_read)
+        tl->table->stats_is_read= TRUE;
     }
   }  
 
@@ -3045,7 +3051,7 @@ void set_statistics_for_table(THD *thd, TABLE *table)
   Use_stat_tables_mode use_stat_table_mode= get_use_stat_tables_mode(thd);
   table->used_stat_records= 
     (use_stat_table_mode <= COMPLEMENTARY ||
-     !stats_cb->stats_is_read || read_stats->cardinality_is_null) ?
+     !table->stats_is_read || read_stats->cardinality_is_null) ?
     table->file->stats.records : read_stats->cardinality;
   KEY *key_info, *key_info_end;
   for (key_info= table->key_info, key_info_end= key_info+table->s->keys;
@@ -3053,7 +3059,7 @@ void set_statistics_for_table(THD *thd, TABLE *table)
   {
     key_info->is_statistics_from_stat_tables=
       (use_stat_table_mode > COMPLEMENTARY &&
-       stats_cb->stats_is_read &&
+       table->stats_is_read &&
        key_info->read_stats->avg_frequency_is_inited() &&
        key_info->read_stats->get_avg_frequency(0) > 0.5);
   }