I have a fairly lightly loaded MySQL server with a few tables that are updated every five minutes. Other than these updates, there are very few queries run against the database. The data is queried just a few times per month. Ever so often, one of the more complicated queries will result in the process getting hung in the "copying to tmp table" state. To be honest, the queries that get hung aren't even that complicated. Usually there's one or two joins, a GROUP BY, and an ORDER BY.
I don't know why SELinux problems seem so frustrating. The problem almost certainly is related to the fact that there is frequently no error message. This is exactly the problem I ran into while turning up a new Apache web server on Red Hat Enterprise Linux 6 (RHEL6) with SELinux enabled.
I recently came across a dev VM running MySQL 5.0.77 (an old release, 28 January 2009) that didn’t have InnoDB available.
skip-innodb wasn’t set,
VARIABLES LIKE '%innodb%' looked as expected, but with one
exception: the value of
I confirmed this with
(root@localhost) [(none)]> show engines; +------------+----------+----------------------------------------------------------------+ | Engine | Support | Comment | +------------+----------+----------------------------------------------------------------+ | MyISAM | DEFAULT | Default engine as of MySQL 3.23 with great performance | | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | | InnoDB | DISABLED | Supports transactions, row-level locking, and …[Read more]
both the oldest and the newest of the popular tools for
automating site administration. Mark Burgess invented it as a
free software project in 1993, and years later, as deployments in
the field outgrew its original design he gave it a complete
rethink and developed the powerful concept of promise
theory to make it modular and maintainable. In this guise as
version 3, CFEngine stands along with two other pieces of free
software, Puppet and Chef, as key parts of enterprise computing.
Along the way, Burgess also started a commercial venture,
CFEngine AS, that maintains both the open source and proprietary
versions of CFEngine.
Diego Zamboni has recently taken the position of Senior Security Advisor at CFEngine AS and is writing a book for O'Reilly on CFEngine 3. I talked to him this week about the recent new …[Read more]
I use snmptrapd to catch SNMP traps and then put them into a MySQL database using a pretty generic trap handler. This gives me the opportunity to generate such useful information as: > SELECT HOUR(time) AS "hour", COUNT(*) AS "bounces" FROM snmptraps WHERE hostname = 'XXX' AND time > '2011-07-25' AND trap_oid = 'SNMPv2-MIB::snmpTrapOID.0 IF-MIB::linkDown' […]
Clearing the Windows DNS Server cache from the command line is an easy task.
C:\> dnscmd . /clearcache
. indicates the local DNS server. You can use
this command to clear the cache of remote DNS servers by
. with the hostname or IP address of
the remote server.
If you're using a non-standard MySQL data directory on your Red Hat Enterprise Linux (RHEL) server, you may have seen an error like /usr/libexec/mysqld: Can't change dir to '/mysql_data/' (Errcode: 13). The key to fixing this problem is to ensure the new MySQL data directory has the proper SELinux security context. In my case: # […]
We ran across the following error on a MySQL slave server recent: mysql> SHOW SLAVE STATUS \G <snip> Last_Error: Query caused different errors on master and slave. Error on master: 'Deadlock found when trying to get lock; try restarting transaction' (1213), Error on slave: 'no error' (0). Default database: '<database_name>'. Query: '<query>' <snip> In this […]
I’m really proud to announce the release of the version 1.0 of mysql-snmp.
What is mysql-snmp?
mysql-snmp is a mix between the excellent MySQL Cacti Templates and a Net-SNMP agent. The idea is that combining the power of the MySQL Cacti Templates and any SNMP based monitoring would unleash a powerful mysql monitoring system. Of course this project favorite monitoring system is OpenNMS.
mysql-snmp is shipped with the necessary OpenNMS configuration files, but any other SNMP monitoring software can …[Read more]
At Days of Wonder we are huge fans of MySQL (and since about a year of the various Open Query, Percona, Google or other community patches), up to the point we’re using MySQL for about everything in production.
But since we moved to 5.0, back 3 years ago our production databases which hold our website and online game systems has a unique issue: the mysqld process uses more and more RAM, up to the point where the kernel OOM decide to kill the process.
You’d certainly think we are complete morons because we didn’t do anything in the last 3 years to fix the issue
Unfortunately, I never couldn’t …[Read more]