It is not hard to agree with a statement about No new global mutexes!. This has been
something we have been preaching since day one when Drizzle was
started. I have lost count on how many we have been able to get
rid of along the way.
Looking through his blog entry I thought I would comment a bit on
some of his points in context for Drizzle:
LOCK_mdl We never had this lock in the first place. It
must have been added in the last year. I suspect this is some
sort of meta-data lock. If we had a good MVCC in-memory engine
sitting around I suspect you could get rid of this lock and
similar cache locks (Drizzle's design doesn't currently require
this sort of shared information, but we are looking for an
in-memory style engine for when we do).
…
Developing websites, social applications, and scripts in PHP for more than 6 years now, I found a number of utility functions helpful in development. I am going to write a series of tutorials writing such functions and describing their use. Using these functions I have created a library of dynamically loadable classes but you are free to use them as you wish.
I am going to discuss the currentURL function in this tutorial.
Developing websites, social applications, and scripts in PHP for more than 6 years now, I found a number of utility functions helpful in development. I am going to write a series of tutorials writing such functions and describing their use. Using these functions I have created a library of dynamically loadable classes but you are free to use them as you wish.
Are you running MySQL on Debian or Ubuntu with InnoDB? You might want to disable /etc/mysql/debian-start. When you run /etc/init.d/mysql start it runs this script, which runs mysqlcheck, which can destroy performance.
It can happen on a server with MyISAM tables, if there are enough tables, but it is far worse on InnoDB. There are a few reasons why this happens -- access to open an InnoDB table is serialized by a mutex, for one thing, and the mysqlcheck script opens all tables. One at a time.
It's pretty easy to get into a "perfect storm" scenario. For example, I'm working with one client right now who has a hosted multi-tenanting application that keeps each customer in its own database. So they have a lot of databases and a lot of tables. And they're running on Amazon EC2 with 8G of RAM and EBS storage, which is slower than typical directly-attached server-grade RAID storage. Since they have a lot of tables, InnoDB uses …
[Read more]Dear Mac users,
There have been a number of issues with configuring XAMP on the
Mac for use with NetBeans IDE, most significantly that XAMP sets
the owners of MySQL databases to "nobody", blocking Apache
access. Therefore I have changed the Mac OS setup tutorial to use MAMP instead of
XAMP. In my opinion, the MAMP setup is more straightforward than
the one for XAMP, anyway.
I’ll keep this short. Let’s say you run “mysql> show slave
status\G” and you see the following error:
Last_Error: Error 'Unknown or incorrect time zone: 'Etc/UTC'' on
query. Default database: 'db_name'. Query: 'INSERT INTO table SET
column = CONVERT_TZ('2009-01-24', '-8:00',
'+00:00')'
It’s a simple fix. Exit out of MySQL and run the following
command - this works on Redhat, I’ve not tried it on other
flavors.
shell> mysql_tzinfo_to_sql /usr/share/zoneinfo|mysql -u root
-p
Log back into MySQL and run the following.
mysql> stop slave;
mysql> start slave;
mysql> show slave status\G;
The error should be gone and the slave should be catching up to
the master now. Problem solved.
The main fixes in cmon 0.13 are:
- filtering of clusterlog
- better graphs interface with filtering
- fixed bug in load average graphs. Now the loadavg graphs works
- added replication role, socket when adding a mysql server to
be monitored from the web interface.
- corrected bug with how often mysql_variables are collected
- fixed problems with graphs
- added images directory
- revamped graphs - now producing files in images directory,
- ajax support for Storage graphs
- divided helpers into smaller files
Upgrade from cmon 0.12
- Stop cmon 0.12 (e.g. killall cmon from the command line)
- Execute this sql script …
This is a simple mysql circular replication implementation on a single machine (just a proof of concept) which can easily be done on a broader scale. Just be aware of the cons of circular replication which mainly gets down to: once a node freaks out or stops for one reason or the other, it’s a bitch and you need to take care of IMMEDIATELY.
Download Sandbox from
https://launchpad.net/mysql-sandbox/+download
Download MySQL from http://dev.mysql.com/downloads
Copy the downloaded software onto the your *nix box onto any folder of your preference called $BASEDIR
run:
cd /$BASEDIR
gunzip mysql_sandbox_X.X.XX.tar.gz
tar -xf mysql_sandbox_X.X.XX.tar
ln -s mysql_sandbox_X.X.XX sandbox
time /$BASEDIR/sandbox/make_replication_sandbox –circular=4 –topology=circular /$BASEDIR/mysql-5.1.30-linux-x86_64-glibc23.tar.gz
user@hostname $ time …
To be specific FTP is File Transfer Protocol and is around for over 30 years. FTP is the simplest and most secure way to exchange files over the Internet. Whether you know it or not, you most likely use FTP all the time. When downloading a file from the Internet you\'re actually transferring the file to your computer from another computer over the Internet. This is why the T (transfer) is in FTP. You may not know where the computer is that the file is coming from but you most likely know it\'s URL or Internet address.
Since MySQL Cluster 6.2 it is possible to setup a pool inside the
mysqld process opening multiple connections to a MySQL Cluster.
This is pretty cool, but it might give troubles when you have to
use Single User Mode.
Take for example the following configuration for your SQL
Nodes:
[SQL]
Id=10
Hostname= 10.100.9.6
[SQL]
Id=11
Hostname= 10.100.9.6
[SQL]
Id=12
Hostname= 10.100.9.7
[SQL]
Id=13
Hostname= 10.100.9.7
No further slots are defined, and you setup your two MySQL
Servers to use connection pooling:
[mysqld]
ndb-cluster-connection-pool = 2
This will result in the following output of SHOW in the ndb_mgm
client tool:
[Read more]
[mysqld(API)] 4 node(s)
id=10 @10.100.9.6 (mysql-5.1.30 ndb-6.3.20)
id=11 @10.100.9.6 (mysql-5.1.30 ndb-6.3.20)
id=12 @10.100.9.7 …