when drop a table, TABLE_STATISTICS not clean it.

[rj03hou]

rt, I think is easy to fix it.

[Valerii Kravchuk (valerii-kravchuk)]

This is really easy to confirm:

[openxs@centos ~]$ mysql -uroot test
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.23-72.1-log Percona Server (GPL), Release 72.1, Revision 0503478

Copyright (c) 2009-2015 Percona LLC and/or its affiliates
Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show variables like 'userstat';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| userstat | OFF |
+---------------+-------+
1 row in set (0.00 sec)

mysql> set global userstat=ON;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like 'userstat';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| userstat | ON |
+---------------+-------+
1 row in set (0.00 sec)

mysql> create table tu(id int primary key);
Query OK, 0 rows affected (0.23 sec)

mysql> insert into tu values(1),(2),(3);
Query OK, 3 rows affected (0.06 sec)
Records: 3 Duplicates: 0 Warnings: 0

mysql> select * from information_schema.table_statistics\G
*************************** 1. row ***************************
          TABLE_SCHEMA: test
            TABLE_NAME: tu
             ROWS_READ: 0
          ROWS_CHANGED: 3
ROWS_CHANGED_X_INDEXES: 3
1 row in set (0.00 sec)

mysql> drop table tu;
Query OK, 0 rows affected (0.05 sec)

mysql> select * from information_schema.table_statistics\G
*************************** 1. row ***************************
          TABLE_SCHEMA: test
            TABLE_NAME: tu
             ROWS_READ: 0
          ROWS_CHANGED: 3
ROWS_CHANGED_X_INDEXES: 3
1 row in set (0.00 sec)

[Elena Stepanova (elenst)]

If you ever get to fixing it, please note it's the same for index statistics after dropping an index, see MDEV-8633.

[Nilnandan Joshi (nilnandan-joshi)]

Verified with 5.5

nilnandan.joshi@bm-support01:~$ mysql -uroot -p --socket=/tmp/mysql_sandbox5544.sock
Warning: Using unique option prefix pass instead of password is deprecated and will be removed in a future release. Please use the full name instead.
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.5.44-37.3 Percona Server (GPL), Release 37.3, Revision 729fbe2

Copyright (c) 2009-2015 Percona LLC and/or its affiliates
Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.13 sec)

mysql> use test
Database changed
mysql> show variables like 'userstat';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| userstat | OFF |
+---------------+-------+
1 row in set (0.02 sec)

mysql> set global userstat=ON;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like 'userstat';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| userstat | ON |
+---------------+-------+
1 row in set (0.00 sec)

mysql> create table tu(id int primary key);
Query OK, 0 rows affected (0.12 sec)

mysql> insert into tu values(1),(2),(3);
Query OK, 3 rows affected (0.00 sec)
Records: 3 Duplicates: 0 Warnings: 0

mysql> select * from information_schema.table_statistics\G
*************************** 1. row ***************************
          TABLE_SCHEMA: test
            TABLE_NAME: tu
             ROWS_READ: 0
          ROWS_CHANGED: 3
ROWS_CHANGED_X_INDEXES: 3
1 row in set (0.00 sec)

mysql> drop table tu;
Query OK, 0 rows affected (0.01 sec)

mysql> select * from information_schema.table_statistics\G
*************************** 1. row ***************************
          TABLE_SCHEMA: test
            TABLE_NAME: tu
             ROWS_READ: 0
          ROWS_CHANGED: 3
ROWS_CHANGED_X_INDEXES: 3
1 row in set (0.00 sec)

mysql>

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-1622