C'est une fonctionnalité... pas un bug.
Les statistiques de la table sont mises en cache. Pour désactiver le cache et toujours avoir la dernière version, vous devez changer la variable du serveur qui indique la durée de l'effacement du cache à 0 :
SET PERSIST information_schema_stats_expiry = 0
La valeur par défaut de cette propriété est passée à 86400 (24 heures) dans Mysql 8.x
Exemple :
SET PERSIST information_schema_stats_expiry = 86400
-- 86400 is the default value of mysql 8.x if you have never changed this you don't need to set this
show variables like 'information_schema_stats_expiry';
+---------------------------------+-------+
| Variable_name | Value |
+---------------------------------+-------+
| information_schema_stats_expiry | 86400 |
+---------------------------------+-------+
create schema mytest;
create table `test` (
`id` int(5) not null auto_increment,
`name` varchar(256),
PRIMARY KEY(`id`)
);
insert into test values(null,'name1')
insert into test values(null,'name2')
insert into test values(null,'name3')
show table status where name like 'test';
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
| Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
| test | InnoDB | 10 | Dynamic | 3 | 5461 | 16384 | 0 | 0 | 0 | 4 | 2018-10-09 15:32:15 | 2018-10-09 15:32:16 | NULL | utf8mb4_0900_ai_ci | NULL | | |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
-- The Auto_increment field is correctly set to 4.. but is now cached.
insert into test values(null,'name3');
show table status where name like 'test';
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
| Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
| test | InnoDB | 10 | Dynamic | 3 | 5461 | 16384 | 0 | 0 | 0 | 4 | 2018-10-09 15:32:15 | 2018-10-09 15:32:16 | NULL | utf8mb4_0900_ai_ci | NULL | | |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
-- The Auto_increment is still 4 (it was cached).
drop schema mytest
Maintenant, nous changeons la configuration :
SET PERSIST information_schema_stats_expiry = 0
et on fait le même test :
show variables like 'information_schema_stats_expiry'
+---------------------------------+-------+
| Variable_name | Value |
+---------------------------------+-------+
| information_schema_stats_expiry | 0 |
+---------------------------------+-------+
create schema mytest;
create table `test` (
`id` int(5) not null auto_increment,
`name` varchar(256),
PRIMARY KEY(`id`)
);
insert into test values(null,'name1');
insert into test values(null,'name2');
insert into test values(null,'name3');
show table status where name like 'test';
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
| Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
| test | InnoDB | 10 | Dynamic | 3 | 5461 | 16384 | 0 | 0 | 0 | 4 | 2018-10-09 15:32:49 | 2018-10-09 15:32:49 | NULL | utf8mb4_0900_ai_ci | NULL | | |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
-- Auto_increment is 4, but the result is not cached!
insert into test values(null,'name3');
show table status where name like 'test';
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
| Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
| test | InnoDB | 10 | Dynamic | 4 | 4096 | 16384 | 0 | 0 | 0 | 5 | 2018-10-09 15:32:49 | 2018-10-09 15:32:49 | NULL | utf8mb4_0900_ai_ci | NULL | | |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+---------------------+------------+--------------------+----------+----------------+---------+
-- The Auto_increment field is now 5 (a correct, not cached value)
drop schema mytest;
