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Today I ran into my first MySQL binlog race condition: The initial problem was quite simple: A typical MySQL master->slave setup with heavy load on the master and nearly no load on the slave, which only serves as a hot fallback and job machine, showed differences on the same table on both machines. The differences showed up from time to time: entries that have been deleted from the master were still on the slave.
After several investigations I started examining the MySQL binlog from the master – a file containing all queries that will be transferred to the slave (and executed there if they don’t match any ignore-db-pattern). I grepped for ids of rows that have not been deleted on the slave as I’s interested if the DELETE statement was
[Read more...]My last post about Basic MySQL Security generated a number of interesting comments, thanks for all your feedback! I'd like to address a few points that were mentioned there:
While the problem seems to be a non-issue on Linux, Keith Murphy stated that the password might still be visible on other Unix operating systems (e.g. Solaris), as described in Bug#11952 in our bug database. According to the bug report, it depends on the implementation of "ps" — there seems to be a BSD variant (/usr/ucb/ps) as well as a SysV implementation (/usr/bin/ps).
[Read more...]I recently had the chance to play with the new T5140 servers. Using the Sparc CMT architecture, these servers present an amazing 128 cpu's to you to use (as a combination of cores and compute threads, there are 2 sockets only).
We are doing some trials with eager Sun customers who want to utilize these babies. The good news is that MySQL Cluster 7.0 (aka 6.4) will support a multi-threaded data node option. The bad news is, one ndbd process still only uses about 8 CPU cores, so to utilize 128, there is some way to go! So the bad news is we still have to launch many ndbd processes to get out the full power of these boxes. But the good news is that with 7.0 there is at least a point in trying at all.
I developed a simple script which lets me easily start a varying amount of ndbd and mysqld processes on one host (and then copy the script to also start same amount of
[Read more...]I recently had the chance to play with the new T5140 servers. Using the Sparc CMT architecture, these servers present an amazing 128 cpu's to you to use (as a combination of cores and compute threads, there are 2 sockets only).
We are doing some trials with eager Sun customers who want to utilize these babies. The good news is that MySQL Cluster 7.0 (aka 6.4) will support a multi-threaded data node option. The bad news is, one ndbd process still only uses about 8 CPU cores, so to utilize 128, there is some way to go! So the bad news is we still have to launch many ndbd processes to get out the full power of these boxes. But the good news is that with 7.0 there is at least a point in trying at all.
I developed a simple script which lets me easily start a varying amount of ndbd and mysqld processes on one host (and then copy the script to also start same amount
[Read more...]I recently had the chance to play with the new T5140 servers. Using the Sparc CMT architecture, these servers present an amazing 128 cpu's to you to use (as a combination of cores and compute threads, there are 2 sockets only).
We are doing some trials with eager Sun customers who want to utilize these babies. The good news is that MySQL Cluster 7.0 (aka 6.4) will support a multi-threaded data node option. The bad news is, one ndbd process still only uses about 8 CPU cores, so to utilize 128, there is some way to go! So the bad news is we still have to launch many ndbd processes to get out the full power of these boxes. But the good news is that with 7.0 there is at least a point in trying at all.
I developed a simple script which lets me easily start a varying amount of ndbd and mysqld processes on one host (and then copy the script to also start same amount
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Ah, the perils of working in a shared, client environment. One client has us using a login that is not exclusive to us. I prefer using bash; the client is set to use zsh. This is not a problem in and of itself.
However, there is a section in the .profile that is causing me issues:
if [ -f /usr/bin/ksh ]; then
/usr/bin/ksh -o vi
exit
fi
So, “If ksh exists, run it with some options to edit history with vi-like commands”. Except what we really want is “If you’re using the ksh as a shell, . . . .”
So I added a modification, and now all is fine.
if [ -f /usr/bin/ksh ]; then
if [ "$SHELL" = "/usr/bin/ksh" ]; then
/usr/bin/ksh -o vi
exit
fi
fi
(not all my problems are MySQL related!)
A lot of you may already know this, but I am willing to bet there are more that don’t. I’m talking about the tee command in the bash shell, and in MySQL. For our purposes, we’ll talk about the tee command in MySQL.
Problem: You have a series of SQL statements whose results take up a few screens worth of output, and you need to take this output and send it to someone else (A DBA, MySQL Support, your mentor). You could just do a copy/paste from your terminal, but what if you realized in the end that your scroll back buffer isn’t as large as you thought it was?
Solution: Tee. Apparently, the mysql client comes with tee.
[Read more...]mysqlshell> tee mysqlog.sql ;
Logging to file ‘mysqlog.sql’
use dbname;
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