Taxonomy upgrade extras:  max_used_connections user account connection configuration

How many connections can be opened concurrently against my MySQL or MariaDB database can be configured and checked with the following command:

SHOW GLOBAL VARIABLES LIKE 'max_connections';
+-----------------+-------+
| Variable_name   | Value |
+-----------------+-------+
| max_connections | 505   |
+-----------------+-------+

If this limit was ever reached in the past can be checked with:

SHOW GLOBAL STATUS LIKE 'max_use%';
+----------------------+-------+
| Variable_name        | …

Generally in MySQL we send queries massaged to a point where optimizer doesn’t have to think about anything. In our major user database environment 99.9% of queries don’t have alternative query plans available (either because of forced indexes or just straightforward Primary Key read). We have various other systems and from time to time we have to do SQL work there and chase optimizer errors.

There’re multiple places where optimizer can make a choice in very basic queries, for example:

• Which index returns less rows
• Which index can be used for ORDER BY

A query that I was looking asked a very basic question, on a job instances table, show state and status for latest-by-ID entry for job name=’Ship Christmas Presents’ (real name was a bit different ;-). So, it was SELECT c,d FROM t WHERE b=X ORDER BY a DESC LIMIT 1, where PK is (a) and a possible index is on …

Learn how VMware Continuent adds HA, DR and real-time data warehouse loading to off-the-shelf MySQL operating on-prem and in VMware vCloud Air public cloud. 

We introduce vCloud Air basics, then do a deep dive into the VMware Continuent system architecture covering important issues like fail-over, zero-downtime maintenance, and load scaling. We will conclude with a demonstration of using

Replication is the process that transfers data from an active master to a slave server, which reproduces the data stream to achieve, as best as possible, a faithful copy of the data in the master.

To check replication health, you may start with sampling the service, i.e. committing some Sentinel value in the master and retrieving it from the slave.

Sentinel data: Tap tap… Is this thing on?
If you want to make sure that replication is working, the easiest test is using replication itself to see if data is being copied across from the master to the slaves. The method is easy:

1. Make sure that the data you want to see is NOT in the master or in the slave. If you skip this step, you may think that replication is working, while in fact it may not.
2. Either create a table …

There is an error which is definitely new to people which have encountered such situation at first time.
It was reported a long time before:
#1689 -> 28 Oct 2003 4:46
#1478 -> 4 Oct 2003 10:58
#7501 -> 23 Dec 2004 5:35

Error is -> ERROR 1054 (42S22): Unknown column ‘c2’ in ‘field list’
The Place where you can encounter this error is something similar below:

mysql> show create table t1;
| t1    | CREATE TABLE `t1` (
  `id` int(11) DEFAULT NULL,
  `c1` varchar(85) DEFAULT NULL
) /*!50100 TABLESPACE innodb_file_per_table */ ENGINE=InnoDB DEFAULT CHARSET=utf8 |

If you try to insert …

Hi Julien
Thanks. As Enterprise Monitor is one of the commercial tools, previous versions can be downloaded from support.oracle.com under the Patches tab. Remember, as part of the Enterprise Edition, you’ll need a valid Support contract.
Hope this helps.
rgds
K.

Thanks a lot for this post.

Unfortunately, i can’t find mysqlmonitoragent v2.3 anymore.

Do you know where i can find it?

Lately I saw many cases when users specified option

--base64-output=DECODE-ROWS

  to print out a statement representation of row events in MySQL binary logs just to get nothing. Reason for this is obvious: option

--base64-output=DECODE-ROWS

  does not convert row events into its string representation, this is job of option

--verbose

. But why users mix these two options so often? This blog post is result of my investigations.

There are already two great blog posts about printing row events on the Percona blog: “Debugging problems with row based replication” by Justin Swanhart and “ …

Thanks to everyone who joined us yesterday for this live session on designing HA for MySQL led by Krzysztof Książek, Senior Support Engineer at Severalnines. The replay and slides to the webinar are now available to watch and read online via the links below.

Watch the replay:

Become a MySQL DBA - webinar series: Which High Availability solution? from Severalnines AB  

Read the slides:

Become a MySQL DBA - webinar series - slides: Which High Availability solution? from …

This post is likely gonna get less relevant when Magento 2 comes out, but I decided to put it out there any way. In my limited time working with Magento I’ve come across a couple scenario’s I wanted to touch on. Hope it’s helpful for anyone.

Let say a merchant wants a new Magento online store. Now, there are a couple scenario’s that are likely or less likely:

1. The previous store was built with Magento. Customers can easily be imported using the various tools available (Magmi, import/export, dataflow, etc.)
2. The previous store was built on a platform that stores passwords in plaintext - fortunately this is not very likely ;)
3. The previous store was built on a different platform, using different hashing algorithms.
4. The previous store was built on a different platform which happens to use the same hashing algorithm as Magento,
5. A combination of #3 and #4 (yes - I’ve seen it). …