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Displaying posts with tag: scheduler (reset)
Automating Backups

If you need to automate backups, you might wonder about the different techniques available to you.

With regards to scheduling backups using built-in features of MySQL, you have two main options:

  • Either run mysqldump (or mysqlbackup if you have an Enterprise licence) from an operating system scheduler, for example in Linux using "cron" or in Windows using the "Task Scheduler". This is the most commonly used option.
  • Alternatively, use the Event Scheduler to perform a series of  SELECT ... INTO OUTFILE ... commands, one for each table you need to back up. This is a less commonly used option, but you might still find it useful.

Scheduling mysqlbackup with cron

mysqldump is a client program, so when you run it, you run it from a shell script, or at a terminal, rather than inside a MySQL statement. The following statement backs up the sakila …

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Another usability bug bites the dust

In MySQL 5.1.33 there is a fix for an apparently innocuous bug.
Bug #36540 CREATE EVENT and ALTER EVENT statements fail with large server_id.
This is a usability bug, that makes the DBA life unnecessarily hard. The reason for having a large server_id is because a DBA might want to use the IP address as server ID, to make sure that there are unique IDs, and to have an easy way of identifying the server through the IP.
All is well until you mix the server_id assignment with event creation:

select version();
| version() |
| 5.1.32 |
1 row in set (0.00 sec)

set global server_id =inet_aton('');
Query OK, 0 rows affected (0.00 sec)

select @@server_id;
| @@server_id |
| …
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Found an Ideal I/O Scheduler for my MySQL boxes

Today I was doing some work on one of our database servers (each of them has 4 SAS disks in RAID10 on an Adaptec controller) and it required huge multi-thread I/O-bound read load. Basically it was a set of parallel full-scan reads from a 300Gb compressed innodb table (yes, we use innodb plugin). Looking at the iostat I saw pretty expected results: 90-100% disk utilization and lots of read operations per second. Then I decided to play around with linux I/O schedulers and try to increase disk subsystem throughput. Here are the results:

Scheduler Reads per second
cfq 20000-25000
noop 35000-60000
deadline 33000-45000
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Showing entries 1 to 3