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…)

So, you have a binlog. You want to find out something specific that happened inside of it. What to do? mysqlbinlog has some neat features, which I thought we would look at here.

I should first explain what mysqlbinlog really is. It is a tool that lets you analyze and view the binlogs/relaylogs from mysql, which are stored in binary format. This tool converts them to plaintext, so that they’re human-readable.

For the first tip, let’s start with the --read-from-remote-server option, which allows you to examine a binlog on a master server in order, perhaps, to dump it onto your slave and compare master/slave logs for potential problems*.

$ mysqlbinlog --read-from-remote-server -uwesterlund -p mysql-bin.000001 -h 127.0.0.1 -P 3306 | head -5
Enter password:
/*!40019 SET @@session.max_insert_delayed_threads=0*/;
/*!50003 SET @OLD_COMPLETION_TYPE=@@COMPLETION_TYPE,COMPLETION_TYPE=0*/;
DELIMITER /*!*/;
# at 4
#080815 19:25:23 server id 101  end_log_pos 107 	Start: binlog v 4, server v 6.0.5-alpha-log created 080815 19:25:23 at startup

Pretty useful!

Now, let’s assume we have a binlog that is 94 lines long*:

(more…)