Many people use MySQL in the console to execute a simple command, but did you know that MySQL can format the result of the query directly to XML or html?
The option -X will output the query result as
XML
-H can be used to generate a HTML table
containing the data.
$ mysql -X -e "select * from test" test
<?xml version="1.0"?>
152710
Output as HTML
$ mysql -H -e "select * from test" test
| test |
|---|
| 152710 |
With our newest release of Percona XtraDB Cluster, I would like to
highlight a very nice ability to recovery a node and bring it
back to the cluster with an incremental transfer after a
crash.
This feature was available even in previous release, but now I
want to give some details.
So, MySQL crashes from time to time and this a fact of life. HA solution is exactly needed to deal with an one node failure and allowing whole cluster continuing to work.
The idea is, if a node crashed, after it recovered – we just transfer all changes that happened in the cluster, while the node was down. It sounds easy in words, but proven hard when it comes to implementation. It all comes to the question: if mysqld crashes, how do we know what is the last transaction was executed. For a single InnoDB instance it is …
[Read more]I’m getting more and more concerned about the current Oracle approach to MySQL security. And the fact that I was solely responsible for the security@mysql.com for about ten years, doesn’t make it easier, on the contrary, it only emphasizes changes in the attitude.
Starting from the obvious — somewhat slower response to critical bug fixes, which can be expected, Oracle is a big company, right? Very little information about security vulnerabilities is disclosed, CPUs are carefully stripped from anything that might help to understand the problem, it takes hours to map them to code changes. Heck, even test cases are kept private now. This seriously smells …
[Read more]The MariaDB project is pleased to announce the immediate availability of the following new stable (GA) MariaDB versions:
[Read more]In my last two posts, I wrote about setting up replication with MySQL 5.6 using Global Transaction Identifiers. Even when I set up replication “the old-fashioned way“, one thought always enters my mind – did all of the data copy over to the slave? And, even after the master/slave has been running for a while, I am always wondering if the data in the slave matches the master. Or did the change that I made to that table make it over to the slave? It is probably more of a case of paranoia on my part, as MySQL replication is very reliable and works really well.
…
[Read more]The duplicate records in a table can be found using below query.
Query 1:
SELECT *, count(pro) as cnt FROM list GROUP BY pro HAVING cnt > 1;
Illustration: The above query will find the duplicate records from list table. The cnt column will show that the duplicate records is available for how many times.
Query 2:
SELECT * FROM list WHERE pro in (SELECT pro FROM list GROUP BY pro HAVING count(pro) > 1);
Illustration: The above query will show all the duplicate records from list table. The duplicate records is based on pro columns.
Tags: DuplicateRecordsCategory: …
[Read more]MySQL accesses files in various places on the file system, and usually this isn't something to worry about. For example, in a standard MySQL 5.5 installation on Ubuntu, the data goes in /var/lib/mysql, and the socket is a file in /var/run/mysqld. It puts configuration files in /etc, logs and binaries in various locations, and it even needs to access some operating system files such as /etc/hosts.allow.
This is all very well until you start trying to be clever and get MySQL to access other parts of the file system. After all, you can configure the location of data, log files, socket, and so on, so why shouldn't you use those settings to optimize your system? Unfortunately, on many modern Linux distributions, it's not that always easy.
Take Ubuntu, for example. Ubuntu comes with something called AppArmor, a kernel-integrated application security system that controls how applications can access the file system. This goes above …
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Challenges
Percona is glad to announce the release of Percona XtraDB Cluster on January 30th, 2013. Binaries are available from downloads area or from our software repositories.
Bugs fixed:
threads_running would become huge. Bug fixed
#1040108 (Teemu Ollakka).
wsrep_defaults_file would be set up to
the value in the last configuration file read. Bug fixed by
keeping the value found in the top configuration file. Bug fixed
…My Mozilla coworkers Ben Kero and Dan Maher gave a standing-room only presentation at Linux Conf AU about “How to Use Puppet Like an Adult”. It was fantastic!
Data != logic
Business DATA does not belong in modules, but business LOGIC is
OK.
What are the data sources, then?
Hiera – lightweight pluggable, hierarchical databases. External
to the modules, you can use many backends, including MySQL. New
feature, standard in puppet 3.0. If you like YAML (and you
should), you’ll like this.
$var = lookup('something') # unscoped (complicated)
$var = lookup('namespace::something') # scoped (yay!)
Another data source is puppetdb. This is a bigger topic, but the important thing is that it can be used for high performance store configs.
Where to find pre-built modules for puppet?
…