Hello Igor, Please find some review feedback below. ===== sql_statistics.cc has this line with comment:

If the value the variable 'use_stat_tables' is set to "preferably" the optimizer uses a particular statistical data only if it can't be found in the statistical data.

the part

uses a particular statistical data only if it can't be found in the statistical data.

doesn't seem to make any sense. Is this a typo? ===== sql_statistics.cc: collect_statistics_for_table() has this code:

table_field->collected_stats->cleanup(); } bitmap_clear_all(table->write_set);

Why suddenly no indentation on the line with the bitmap_clear_all() call? This looks as if a merge has gone wrong, please fix. ===== sql_statistics.cc has this :

class Table_stat: public Stat_table {

private:

Field *db_name_field; /* Field for the column table_stats.db_name */

Why do all class definitions start with 'private:'? It is active by default in C++. The code looks as if it was auto-translated from some other language. ===== I see that my progress reporting patch from November is not part of the tree yet. ===== I don't any code that would check if table DDLs of statistical tables are what the server expects them to be. I think the check should be made, just like it is made for mysql.proc and other tables. ==== Then I started to play with the code and have filed MDEV-4350, MDEV-4357, MDEV-4359, MDEV-4360, MDEV-4362, MDEV-4363, MDEV-4364. I find it difficult to proceed when there are so many simple counterexamples. BR Sergei -- Sergei Petrunia, Software Developer Monty Program AB, http://askmonty.org Blog: http://s.petrunia.net/blog