Hello Igor, TABLE_SHARE has TABLE_STATISTICS_CB, which has these members: struct TABLE_STATISTICS_CB { ... bool stats_is_read; /* Statistical data for table has been read from statistical tables */ bool histograms_are_read; } At the same time, TABLE has: struct TABLE { ... bool stats_is_read; /* Persistent statistics is read for the table */ bool histograms_are_read; I would like to understand why both structures need these variables? Is there any difference in meaning between them? BR Sergei -- Sergei Petrunia, Software Developer MariaDB Corporation | Skype: sergefp | Blog: http://s.petrunia.net/blog