Sometimes it is nice to show customers the functionality of
MySQL-Enterprise Monitor (aka Merlin). I install the agents on
the servers and the dashboard runs on my laptop. But very often
only ssh is open to these servers.
So how to dig a whole through the firewall for MySQL-Enterprise
Monitor?
laptop> ssh -R 18080:localhost:18080
oli@where_the_agent_sitsMaybe trivial for you but for me its hard
to remember...
May
18
2008
May
18
2008
I've uploaded MySQL Replication Manager's (mysqlreplicationmanager) screenshot and Screencast
Video / Screencast
You can download a full size video from here.
May
18
2008
I've uploaded MySQL Replication Manager's (mysqlreplicationmanager) screenshot and Screencast
Video / Screencast
You can download a full size video from here.
May
17
2008
If you use replication with MySQL and memcache at the same time you have the problem to make sure that the memcached and the slave are in sync. If you announce the memcached to mark a entry as dirty and let it update the value from the slave BEFORE it is updated, you fetch a old value.
The easiest way to ensure that memcache is always notified after the slave is updated, you can use ... well ... replication. MySQL 5.1 brings Row Based Replication that makes this kind of applications a lot easier.
I'm not there to present you a Proof of Concept, I'm only close enough to explain the idea:
- Slave fetches records from Master
- Slave applies the records
- Slave exposes its changes as replication stream to the MySQL Proxy
- MySQL Proxy decodes the RBR records, extracts the Primary Key and updates the content in the memcache server
The MySQL Proxy acts as replication client …
[Read more]
May
17
2008
I understand that MySQL as a company wants to recruit paying customers. However, as a community user I have a hard time finding what I want on the MySQL website. Today’s frustration is brought to you by trying to find the documentation.
Go ahead, hit http://www.mysql.com. From there, where do you go to find the documentation?
It’s not Services, not even Services -> Support.
According to Products, the community server is not even a product. How is a potential new user, who wants to learn about MySQL, supposed to know a community version exists? Here are the products listed on the Products page:
MySQL Enterprise
MySQL Enterprise Monitor
MySQL Cluster
MySQL Embedded Database
MySQL Database Drivers
MySQL Database Tools
Where’s “MySQL Database” on that list? A website user basically has to know what they’re …
[Read more]
May
17
2008
So today Roman, one of the developers on the Doctrine project, pointed me to an article that was discussing the misuse of DISTINCT. This article went so far as to say that "A SELECT DISTINCT query is frequently a "code smell". The article pointed to another article hosted at onlamp.com. That author was advocating the use of subqueries to more efficiently filter out redundant rows. Immediately I began to wonder if this is really a feasible approach since MySQL's subquery handling is very slow. I could imagine this being faster on RDBMS where the subquery implementation is more mature. That being said comments in the onlamp.com article point to the fact that even on Oracle things get slower with the …
[Read more]
May
17
2008
One of the most frequently needed functionality in the MySQL Proxy is the need to know which server you are on. This is not given, on purpose, by the proxy, because the proxy is supposed to be transparent. It is not supposed to matter which back-end server you are on.
However, for testing purposes we often want to know which
back-end server we’re on. Thus I developed functionality for
SHOW PROXY BACKEND [INDEX ADDRESS OTHER].
SHOW PROXY BACKEND INDEX — gives the index of the
server you’re on (backend_ndx, ie 1)
SHOW PROXY BACKEND ADDRESS — gives the address of
the server you’re on (ie, foo.bar.com:3306)
SHOW PROXY BACKEND OTHER — gives the address of all
the other servers except those you’re not on, in multiline
format.
Note that I was pretty lazy and the commands are case-sensitive. But I figured that since this is supposed to be used …
[Read more]
May
17
2008
I need help from my fellow mysql users. I know some of the people who read this are alot better then me with mysql so hopefully you can help
So today we decided that we are going to migrate one of our master database servers to new hardware. Since we got the hardware this morning and we wanted to move on to it asap, we decided that we will take our slave down, copy data from it, and bring it up on future master server. At that point, we will let it run as slave to the current master server until its time for us to take it down. Reason we did that instead of mysqldump/import was to avoid the lag mysqldump creates on our server.
After we did all this and put up the new master server, we started to notice odd issues. After looking around and comparing old db with new, we found out that new db was missing data. How it happened is beyond me and is the reason why I am writing this. …
[Read more]
May
16
2008
Let me prefix this post by stating that I’m a developer and not a business analyst, but I wanted to point out something that strikes me as a bit contradictory. In recent posts like these by Savio Rodrigues and Matt Asay, there are references that say the commercial plugins MySQL/Sun was planning on releasing were part of an OSS business model. While the plugins would have been tied to an OSS project, the products themselves would have been commercial*. I think these products (and other current products MySQL/Sun offers only as closed source) should actually be considered as commercial product offerings (under a commercial business model), and not associated with a pure OSS business model. To me (and some may disagree) an …
[Read more]
May
16
2008
It is that time of the year when many PostgreSQL fans gather in
Ottawa, Canada for PGCon 2008 next week. This will be my first
visit to PGCon in Ottawa. Earlier this year I had presented two
sessions "PostgreSQL and Benchmarks" and "Best Practices of
PostgreSQL on Solaris" at PostgreSQL Conference 2008 East in
Maryland. Thanks to that visit, this time I might recognize many
people by face this time around.
Sun is a Gold Sponsor at PGCon 2008. There will be quite a bit of presence from Sun in PGCon. Josh, Max, Robert, Magne, Zdenek, Jim, Mayuresh et all will be present out there.
Josh Berkus is doing a tutorial on "GUCs: A Three Hour Tour" on …
[Read more]