VividCortex is sponsoring and exhibiting at Percona Live EU in Amsterdam September 21 - 23rd. Stop by our booth to get a free product demo and see how we can revolutionize your database monitoring.
Baron Schwartz will also be speaking on Redis Eye for the MySQL Guy, so be sure to learn from his experience.
Click here for more details and registration.
This Log Buffer Edition throws spotlight on some of the salient blog posts from Oracle, SQL Server and MySQL.
Fri, 2015-07-31 12:14guillaumelefranc
Mandatory disclaimer: the techniques described in this blog post are experimental, so use at your own risk. Neither me nor MariaDB Corporation will be held responsible if anything bad happens to your servers.
Context
MaxScale 1.2.0 and above can call external scripts on monitor events. In the case of a classic Master-Slave setup, this can be used for automatic failover and promotion using MariaDB Replication Manager. The following use case is exposed using three MariaDB servers (one master, two slaves) and a MaxScale server. Please refer to my Vagrant files if you want to jumpstart such a testing platform.
Requirements
Article on Information Age:
From obscurity to the mainstream, the journey of MySQL shows the power of the open source community to drive innovation. Read the full article here: http://goo.gl/bqFZPb
Welcome to the 10th episode in the MySQL QA series! Today we’ll talk about reproducing and simplifying: How to get it Right.
Note that unless you are a QA engineer stuck on a remote, and additionally difficult-to-reproduce or difficult-to-reduce bug, this episode will largely be non-interesting for you.
However, what you may like to see – especially if you watched episodes 7 (and possibly 8 and 9) – is how reducer automatically generates handy start/stop/client (cl) etc. scripts, all packed into a handy bug tarball, in combination with the reduced SQL testcase.
This somewhat separate part is covered directly after the introduction (ends at 11:17), as well as with an example towards the end of the video (starts at time index 30:35).
The “in between part” (11:17 to 30:35) is all about reproducing and simplifying, which – unless you are working on a remote case – can likely be skipped by …
[Read more]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 | …[Read more]
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:
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:
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 …
[Read more]