Somebody asked how to create a SYNONYM in MySQL, which is interesting because MySQL doesn’t support synonyms. I thought the prior entry explained how to do it, but here’s a new post. However, you can create a view in one database that relies on a table in another database.

The following SQL statements create two databases and grant appropriate privileges to the student as the root superuser:

/* Create two databases. */
CREATE DATABASE seussdb;
CREATE DATABASE appdb;
 
/* Grant privileges to a student user. */
GRANT ALL ON seussdb.* TO student;
GRANT ALL ON appdb.* TO student;

Log out from the root superuser and reconnect as the student user. Then, the following code connects to the seuss …

One of the latest labs releases of Oracle MySQL brings multi source replication. This lifts the limitation found in earlier releases that a MySQL slave can only have one master.

To be fair, there were other ways of doing this already:

• Using a time based switch as described in MySQL High Availability
• Using the multi source feature in the yet-to-be released MariaDB 10
• Using Tungsten Replicator

There are many good uses of multi source replication. You could use it to combine data from multiple shards or applications.

If MySQL is used with …

Table of Content

• Introduction
• Prerequisites
• What is MyEnv?
• MySQL Workbench configuration.
  • Prepare MySQL start and stop scripts.
  • Add MySQL connections in MySQL Workbench.
  • …

Table of Content

• Introduction
• Prerequisites
• What is MyEnv?
• MySQL Workbench configuration.
  • Add MySQL connections to MySQL Workbench.
  • Start/Stop instance configurations.

Introduction

MySQL Workbench is a …

As Frederic posted, its time to submit talks for the MySQL & Friends Devroom at FOSDEM 2014. The next year, it will be on Saturday February 1 2014. I look forward to being in Brussels again, and I hope to see you there too.

Submit to the MySQL track here, and don’t forget to be there on Friday evening for the start of the beers. I’m told by Frederic & Kenny that we’re likely to have a much more interesting community dinner since things are getting larger year by year. See you at FOSDEM and remember, submit talks!

…

Amazon recently announced support for 5.6, unfortunately, direct upgrade from lower versions is not yet supported. On a recent migration work – running mysqldump flat out would’ve meant 6+hrs of downtime. How did we cut it off to 1h45m? Simple, run dump per table and pipe it directly to the new 5.6 instance in parallel using Percona Server’s mysqldump utility to take advantage of –innodb-optimize-keys.

Here’s the base script we used – of course, YMMV and make sure to optimize the destination instance as well!

#!/bin/bash
# export-run.sh
# This is the wrapper script which builds up the list of tables to split into $parallel parts and calls export-tables.sh

parallel=6
dblist="db1 db2 db3"
smysql="mysql -hsource-55.us-east-1.rds.amazonaws.com"
dmysql="mysql -hdest-56.us-east-1.rds.amazonaws.com" …

Everyone who works with MySQL (or MariaDB) query optimizer has to spend a lot of time looking at EXPLAIN outputs. You typically first look at the tabular form, because it is easier to read. You can immediately see what the join order is, what numbers of records will be read, etc:

MariaDB [dbt3sf1]> explain select * from customer, orders where c_custkey= o_custkey;
+------+-------------+----------+------+---------------+-------------+---------+----------------------------+--------+-------+
| id   | select_type | table    | type | possible_keys | key         | key_len | ref                        | rows   | Extra |
+------+-------------+----------+------+---------------+-------------+---------+----------------------------+--------+-------+
|    1 | SIMPLE      | customer | ALL  | PRIMARY       | NULL        | NULL    | NULL                       | 150303 |       |
|    1 | SIMPLE      | orders   | ref  | i_o_custkey   | i_o_custkey | 5       | …

Now that Percona XtraDB Cluster 5.6 is out in beta, I wanted to start a series talking about new features in Galera 3 and PXC 5.6.  On the surface, Galera 3 doesn’t reveal a lot of new features yet, but there has been a lot of refactoring of the system in preparation for great new features in the future.

Galera vs MySQL options

wsrep_provider_options is a semi-colon separated list of key => value configurations that set low-level Galera library configuration.  These tweak the actual cluster communication and replication in the group communication system.  By contrast, other PXC global variables (like ‘wsrep%’) are set like other mysqld options and generally have more to do with MySQL/Galera …

What do swaying palms, turquoise water, white sandy beaches and absolutely pristine fauna remind you of? Correct! It’s Log Buffer. This Log Buffer brings you beads of blog posts related to data dexterity crafted by leading bloggers across the planet.

Oracle:

When are Exadata’s storage indexes used?

Oracle 12c has increased the maximum length of character-based columns to 32K bytes.

Oracle has extended the maximum length of varchar2, nvarchar and raw columns to 32K, but this comes with some challenges when it comes to indexing such columns.

…

How about MySQL 5.7 innodb memcached!