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  1. MariaDB Server
  2. MDEV-16844

Real maximum value for rocksdb_max_row_locks is 1024*1024

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      Description

      KB article (https://mariadb.com/kb/en/library/myrocks-system-variables/#rocksdb_max_row_locks) says that maxumum possible and default value of rocksdb_max_row_locks is 10.24*1024*1024 (1073741824).

      In reality it's just 1024*1024 (1048576) and this may be too small to efficiently convert large tables to InnoDB. Consider the following test:

      MariaDB [test]> set session rocksdb_max_row_locks = DEFAULT;
      Query OK, 0 rows affected (0.001 sec)
       
      MariaDB [test]> select @@rocksdb_max_row_locks;
      +-------------------------+
      | @@rocksdb_max_row_locks |
      +-------------------------+
      |                 1048576 |
      +-------------------------+
      1 row in set (0.001 sec)
       
      MariaDB [test]> set global rocksdb_max_row_locks = DEFAULT;
      Query OK, 0 rows affected (0.001 sec)
       
      MariaDB [test]> show global variables like '%max_row_locks';
      +-----------------------+---------+
      | Variable_name         | Value   |
      +-----------------------+---------+
      | rocksdb_max_row_locks | 1048576 |
      +-----------------------+---------+
      1 row in set (0.006 sec)
       
      MariaDB [test]> set global rocksdb_max_row_locks = 10*1024*1024;
      Query OK, 0 rows affected, 1 warning (0.001 sec)
       
      MariaDB [test]> show warnings\G
      *************************** 1. row ***************************
        Level: Warning
         Code: 1292
      Message: Truncated incorrect rocksdb_max_row_locks value: '10485760'
      1 row in set (0.001 sec)
       
      MariaDB [test]> show global variables like '%max_row_locks';
      +-----------------------+---------+
      | Variable_name         | Value   |
      +-----------------------+---------+
      | rocksdb_max_row_locks | 1048576 |
      +-----------------------+---------+
      1 row in set (0.005 sec)
      

      This may have something to do with MDEV-13609.

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            Assignee:
            greenman Ian Gilfillan
            Reporter:
            valerii Valerii Kravchuk
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              Created:
              Updated:
              Resolved: