[MDEV-16844] Real maximum value for rocksdb_max_row_locks is 1024*1024 Created: 2018-07-29  Updated: 2020-08-25  Resolved: 2018-09-12

Status: Closed
Project: MariaDB Server
Component/s: Documentation, Storage Engine - RocksDB
Affects Version/s: 10.2.15, 10.3.7
Fix Version/s: N/A

Type: Bug Priority: Major
Reporter: Valerii Kravchuk Assignee: Ian Gilfillan
Resolution: Fixed Votes: 0
Labels: documentation, rocksdb, variable


 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.



 Comments   
Comment by Sergei Petrunia [ 2018-09-04 ]

I have merged a change into 10.2 from the upstream that makes the new maximum to be 1024*1024*1024 . Documentation will need to be updated.

Comment by Ian Gilfillan [ 2018-09-04 ]

psergey can you link to this push? I presume it'll be in 10.3.10 and 10.2.18?

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