Scenario: Master-Master replication
Description: Master A is the active db server whilst Master B is a read only swappable db server hence both are creating binary logs. During backup I run “FLUSH LOGS” in order to have a simpler point in time recovery procedure if that case arises.
Problem: Flush logs is mean mean command :) …. it rotates not only my binary logs but my error log too (since I user error-log=blahblahblah in my my.cnf). Well given I flush logs every night my error log is cycled through every night, but unlike binary logs which have an incrimental number attached to the fine, error logs only have a `-log` attached to the filename and a second “FLUSH LOG” would just clear all error logs permanently. That is really not fun believe me!

So what is the solution? you could either:
1. Not use “FLUSH LOGS” (nah that aint happenin)
2. Not use –error-log (that aint happenin either cos I need to …

As I've been doing the last couple of years, I will be going to the O'Reilly MySQL Conference & Expo. In addition to the tutorial and the replication sessions that I will be holding together with Lars, I will be holding a session about the binary log together with Chuck from the Backup team which the Replication team normally works very close with.

This year, O'Reilly also have a Friend of the Speaker discount of 25% that you can use when you register using the code mys10fsp.

The sessions that we are going to hold are listed below. Note that I am using Microformats, which will …

Applying binary logs to a MySQL instance is not particularly difficult, using the mysqlbinlog command line utility:

$> mysqlbinlog mysql-bin.000003 > 03.sql
$> mysql < 03.sql

Turning off binary logging for a session is not difficult, from the MySQL commandline, if you authenticate as a user with the SUPER privilege:

mysql> SET SESSION sql_log_bin=0;

However, sometimes you want to apply binary logs to a MySQL instance, without having those changes applied to the binary logs themselves. One option is to restart the server binary logging disabled, and after the load is finished, restart the server with binary logging re-enabled. This is not always possible nor desirable, so there’s a better way, that works in at least versions 4.1 and up:

The mysqlbinlog utility has the --disable-log-bin option. All the option does is add the SET …

Recently with a client while running a number of disaster recovery tests I came across a nasty situation which was not part of the original plan and provided a far worse disaster situation then expected.

I should preface this condition with some of the environment conditions.

• MySQL 5.0 Enterprise 5.0.54
• RHEL 5 64bit
• Master and 2 Slaves
• MySQL Data and MySQL Binary Logs/MySQL Error Logs are on separate disk partitions

While running stress tests under high load, we tested the filling of partition containing the logs. This partition included the binary log and MySQL error log.

The observed output was.

• An error message was written to the MySQL error log. See below.
• Application throughput dropped, but did not stop.
• Binary logs stopped occuring.
• MySQL proactively stopped logging but continued to process …

There has been much talking about MySQL performance related to logging. Since MySQL 5.1.21, when Bug #30414 was reported (Slowdown (related to logging) in 5.1.21 vs. 5.1.20) I have been monitoring the performance of the server, both on 5.0 and 5.1.
Recently, I got a very powerful server, which makes these measurements meaningful.
Thus, I measured the performance of the server, using all publicly available sources, because I want this benchmark to be repeatable by everyone.
I will first describe the method used for the benchmarks, and then I report the results.The serverThe server is a Linux Red Hat Enterprise 5.2, running on a 8core processor, with 32 GB RAM and 1.5 TB storage.

$ cat /etc/redhat-release
Red Hat Enterprise Linux Server release 5.2 (Tikanga)

$ cat /proc/cpuinfo |grep "processor\|model name" | sort …

Warning... what follows is a murky mess.
It's filed as MySQL bug#43398 (verified!) but it's triggered by cPanel doing evil.

Scenario....Start a mysql server, as normal
Then run mysql_install_db (as root, like you would when you first install MySQL)
See a new binlog file get created, with ownership/group root!Of course you generally wouldn't run mysql_install_db while a server is running, but there's nothing to prevent you (or something else) from doing so!
--bootstrap just shouldn't initialise binlog, then there wouldn't be a issue.

cPanel runs mysql_install_db in its automatic upgrade scripts (dangerous already, automatically upgrading MySQL Server on a system!), it's run every night on cPanel systems even if no upgrade is done, and it behaves exactly as described above. It then chowns the binlog files to mysql:mysql which is of course …

Recently I had an interesting issue crop up. Due to an unfortunate migration incident in which involved master/master replication and not checking to see if replication was caught up, we ended up with an infinite replication loop of a number of SQL statements. awk helped immensely in the aftermath cleanup.

The basics of the replication infinite loop were (more…)

Back when I started working with computers, you actually carved each character with a machine into oddly shaped pieces of paper. My FORTRAN class required up to two dozen of these carefully manicured pieces of paper for each program. The folks in the RPG class had litterally stacks of data one or two feet deep and my mind boggled at the amount of data these poor folks had to carry around with them. My best guess now is that they may have had up to two thousand records of up to 80 characters. My lowly FORTAN class saw the RPG programming class as demi-gods as they trudged along with trays of cards under their arms.

And then one day it rained. Data cards were sensitive to humidity especially the type of humidity you find in the bottom of a rain filled gutter, 12-edge down. My fellow students and I commiserated with one of those formerly envied RPG students as we viewed what was now a paper mache lump. The object of our empathy had …

For example, after executing this code:

create table t1 (id int, c char(10), d date);
insert into t1 values (1, 'abc', '2008-01-01');
insert into t1 values (2, 'def', '2008-08-19');
insert into t1 values (3, 'ghi', current_date());
select * from t1; …