[#MDEV-32580] The value of cardinality in mysql.table_stats may exceed by more than 10% the actual number of records in the table

create table t1 (a int);

insert into t1 select 1000 from seq_1_to_1000;

insert into t1 select 10 from seq_1_to_1000;

insert into t1 select 10000 from seq_1_to_100;

set analyze_sample_percentage=20;

analyze table t1 persistent for all;

analyze table t1 persistent for all;

we will get a new value for cardinality in mysql.table_stats. And very often this value will exceed 2100 and and sometimes more than 10% the actual number of records in the table.
E.g.:

MariaDB [mysqltest]> select * from mysql.table_stats where table_name='t1';

+-----------+------------+-------------+

| db_name   | table_name | cardinality |

+-----------+------------+-------------+

| test      | t1         |        2360 |

+-----------+------------+-------------+

MariaDB [mysqltest]> explain extended select * from t1 where a between 1500 and 1600;

+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+

| id   | select_type | table | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |

+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+

|    1 | SIMPLE      | t1    | ALL  | NULL          | NULL | NULL    | NULL | 2360 |    33.33 | Using where |

+------+-------------+-------+------+---------------+------+---------+------+------+----------+-------------+

[MDEV-32580] The value of cardinality in mysql.table_stats may exceed by more than 10% the actual number of records in the table Created: 2023-10-25 Updated: 2023-11-26
Status:	Open
Project:	MariaDB Server
Component/s:	None
Affects Version/s:	10.6
Fix Version/s:	10.6

[MDEV-32580] The value of cardinality in mysql.table_stats may exceed by more than 10% the actual number of records in the table Created: 2023-10-25 Updated: 2023-11-26