The latest from the MySQL community

Queries have to be cached in every heavily loaded database, there is simply no way for a database to handle all traffic with reasonable performance. There are various mechanisms in which a query cache can be implemented. Starting from the MySQL query cache, which used to work just fine for mostly read-only, low concurrency workloads and which has no place in high concurrent workloads (to the extent that Oracle removed it in MySQL 8.0), to external key-value stores like Redis, memcached or CouchBase.

The main problem with using an external dedicated data store (as we would not recommend to use MySQL query cache to anyone) is that this is yet another datastore to manage. It is …

We see sometimes at customers that they have very big InnoDB system tablespace files (ibdata1) although they have set innodb_file_per_table = 1.

So we want to know what else is stored in the InnoDB system tablespace file ibdata1 to see what we can do against this unexpected growth.

First let us check the size of the ibdata1 file:

# ll ibdata1 
-rw-rw---- 1 mysql mysql 109064486912 Dez  5 19:10 ibdata1

The InnoDB system tablespace is about 101.6 Gibyte in size. This is exactly 6'656'768 InnoDB blocks of 16 kibyte block size.

So next we want to analyse the InnoDB system tablespace ibdata1 file. For this we can use the tool innochecksum:

# innochecksum --page-type-summary ibdata1 
Error: Unable to lock file:: ibdata1
fcntl: Resource temporarily unavailable

But... the tool …

We see sometimes at customers that they have very big InnoDB system tablespace files (ibdata1) although they have set innodb_file_per_table = 1.

So we want to know what else is stored in the InnoDB system tablespace file ibdata1 to see what we can do against this unexpected growth.

First let us check the size of the ibdata1 file:

# ll ibdata1 
-rw-rw---- 1 mysql mysql 109064486912 Dez  5 19:10 ibdata1

The InnoDB system tablespace is about 101.6 Gibyte in size. This is exactly 6'656'768 InnoDB blocks of 16 kibyte block size.

So next we want to analyse the InnoDB system tablespace ibdata1 file. For this we can use the tool innochecksum:

# innochecksum --page-type-summary ibdata1 
Error: Unable to lock file:: ibdata1
fcntl: Resource temporarily unavailable

But... the tool …

Working on a test case with sysbench, I encountered this:

mysql> select * from sbtest1 where id = round(rand()*10000, 0);
+------+--------+-------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------+
| id   | k      | c                                                                                                                       | pad                                                         |
+------+--------+-------------------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------+
|  179 | 499871 | 09833083632-34593445843-98203182724-77632394229-31240034691-22855093589-98577647071-95962909368-34814236148-76937610370 | 62233363025-41327474153-95482195752-11204169522-13131828192 |
| 1606 | 502031 | …

We are happy to confirm our attendance at another two shows which are going to happen in a couple of days. They are OpenSource Conference in Fukuoka & IT.Tage in Frankfurt, Germany. Please find details below:

• Name: OpenSource Conference Fukuoka
• Place: Fukuoka, Japan
• Date: December 8, 2018
• Where to find us:
  • at the MySQL booth in the expo area
  • at the MySQL talk on: "State of Dolphin" given by Yoshiaki Yamasaki, the MySQL Senior Sales Consultant Asia Pacific and Japan. See the official schedule on conference website for the timing and place.
• Name: IT.Tage 2018
• Place: Frankfurt, Germany
• Date: December 10-13, 2018
• Where to find us:
  …

Delayed replication allows a replication slave to deliberately lag behind the master by at least a specified amount of time. Before executing an event, the slave will first wait, if necessary, until the given time has passed since the event was created on the master. The result is that the slave will reflect the state of the master some time back in the past. This feature is supported since MySQL 5.6 and MariaDB 10.2.3. It can come in handy in case of accidental data deletion, and should be part of your disaster recovery plan.

The problem when setting up a delayed replication slave is how much delay we should put on. Too short of time and you risk the bad query getting to your delayed slave before you can get to it, thus wasting the point of having the delayed slave. Optionally, you can have your delayed time to be so long that it …

Percona announces the release of Percona Server for MySQL 5.7.24-26 on December 4, 2018 (downloads are available here and from the Percona Software Repositories). This release merges changes of MySQL 5.7.24, including all the bug fixes in it. Percona Server for MySQL 5.7.24-26 is now the current GA release in the 5.7 series. All of Percona’s software is open-source and free.

This release includes fixes to the following upstream CVEs (Common Vulnerabilities and Exposures): CVE-2016-9843, CVE-2018-3155, …

For the third year in a row, we will take advantage of the mass presence of our MySQL Engineers during FOSDEM to organize the pre-FOSDEM MySQL Day.

The program of this 3rd edition is already on track, thank you to all the speakers who already confirmed their participation.

Announcing the opening of the Percona Live 2019 Open Source Database Conference call for papers. It will be open from now until January 20, 2019. The Percona Live Open Source Database Conference 2019 takes place May 28-30 in Austin, Texas.

Our theme this year is CONNECT. ACCELERATE. INNOVATE.

As a speaker at Percona Live, you’ll have the opportunity to CONNECT with your peers—open source database experts and enthusiasts who share your commitment to improving knowledge and exchanging ideas. ACCELERATE your projects and career by presenting at the premier open source database event, a great way to build your personal and company brands. And …

The MySQL, MariaDB and Friends devroom was once again flooded with submissions. The committee, consisting of community members Daniël van Eeden, Art van Scheppingen, Giuseppe Maxia and Aurélien Lequoy, as well as Tom de Cooman for Percona, Vicentiu Ciorbaru for MariaDB and Nuno Carvalho for MySQL/Oracle, had the difficult job of whittling down 67 submissions into the final 17.

The following sessions were selected: