Have you ever had a case where you needed to find a process which sent a HUP/KILL/TERM or other signal to your database? Let me rephrase. Did you ever have to find which process messed up your night? If so, you might want to read on. I’m going to tell you how you can find it.

Granted, on small and/or meticulously managed systems tracking down the culprit is probably not a big deal. You can likely identify your process simply by checking what processes have enough privileges to send mysqld a HUP/KILL/TERM signal. However, frequently we see cases where this may not work or the elimination process would be too tedious to execute.

We recently had a case where a process was frequently sending SIGHUPs to mysqld and the customer asked us to see if we could get rid of his annoyance. This blog is the direct result of a discussion I had with my colleague …

Taxonomy upgrade extras: partitionrenameDDL

Before I forget it and have to search again here a short note about how to rename a MySQL Partition:

My dream:

ALTER TABLE history RENAME PARTITION p2015_kw10 INTO p2015_kw09;

In reality:

ALTER TABLE history
REORGANIZE PARTITION p2015_kw10 INTO (
PARTITION p2015_kw09 VALUES LESS THAN (UNIX_TIMESTAMP('2015-03-02 00:00:00'))
);

Caution: REORGANIZE PARTITION causes a full copy of the whole partition!

Hint: I assume it would be very easy for MySQL or MariaDB to make this DDL command an in-place operation...

…

Configuration

1) Download the utilities. Python connector is a prerequisite and this needs to be installed along with mysql utilities rpm

wget http://dev.mysql.com/get/Downloads/Connector-Python/mysql-connector-python-2.0.2-1.el6.noarch.rpm

wget http://dev.mysql.com/get/Downloads/MySQLGUITools/mysql-utilities-1.5.3-1.el6.noarch.rpm

2) Install the RPMs. “Mysqlfailover –help” will confirm the install of the utilities

rpm –ivh mysql-connector-python-2.0.2-1.el6.noarch.rpm

rpm -ivh mysql-utilities-1.5.3-1.el6.noarch.rpm

3) Set the GTID MODE to ON. GTID mode is a prerequisite for mysqlfailover. GTID tracks the transaction IDs for replication instead of tracking log file and position

log-bin=1

gtid_mode=ON

enforce_gtid_consistency=true

log-slave-updates=1

4) Setup replication using …

As part of optimising scan execution by about 50% in MySQL Cluster 7.4
we made an effort to also write down a description of the scan protocol
locally within the LDM threads. This is documented in the source code of
MySQL Cluster 7.4 and here is an excerpt from the source code.

DBLQH controls the execution of scans on tables on behalf of DBTC and
DBSPJ. Here follows a signal overview of how a scan is performed within
one LDM instance. For a description of the global scan protocol
see DbtcMain.cpp as a comment before execSCAN_TABREQ.

DBLQH only controls execution of a scan towards one partition of a
table. DBTC/DBSPJ is responsible for execution of scans toward the
entire table and ensuring that the API sees a consistent view of the
table.

There are currently four types of scans implemented in one LDM
instance:

…

From time to time we detect query patterns that are not well fitted to the BTree+ structures provided by InnoDB. One such situation is when you need to traverse a hierarchy (tree) or graph structure with many nodes. Specialist databases exist for this such as Neo4J. However there exists a simple solution in the form of  OQGraph which is distributed with MariaDB and is documented here.

The OQGRAPH engine is based on an original idea by Open Query founder Arjen Lentz, and was developed in-house with Antony Curtis at Open Query.

A …

MariaDB 10.1.3 was recently released, and is available for download here:

https://downloads.mariadb.org/mariadb/10.1.3/

This is the 1st beta, and 4th overall, release of MariaDB 10.1, so there are a lot of new changes, functionalities added, defaults changed, and many bugs fixed (I counted 420 – 117 in 10.1.2 & 637 in 10.1.1, fwiw).

Since it’s beta, I’ll only cover the major changes and additions, and omit covering general bug fixes (feel free to browse them all here).

To me, these are the highlights of the new features:

• Table and Tablespace Encryption.
• …

MySQL 5.6.23 was recently released (it is the latest MySQL 5.6, is GA), and is available for download here.

For this release, there is 1 “Security Note”, 3 “Functionality Changed”, and 5 “Compilation Notes”, all benign, but let me address them:

1. Security Note: The linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1j to version 1.0.1k. Issues fixed in the new version are described at http://www.openssl.org/news/vulnerabilities.html.
2. Functionality Changed: Support for the SSL 2.0 and SSL 3.0 protocols has been disabled because they provide weak encryption. (Bug #19820550, Bug #19921150)
3. Functionality Changed: yaSSL was upgraded to version …

MariaDB 5.5.42 was recently released (it is the latest MariaDB 5.5), and is available for download here:

https://downloads.mariadb.org/mariadb/5.5.42/

This is a maintenance release, and so there were not too many changes at all and only 3 changes (enhancements) I felt noteworthy:

• The new version of the Audit Plugin is 1.2 is included with the following new features:
  • In the audit log passwords are now masked, i.e. the password characters are replaced with asterisks.
  • It’s now possible to filter logging to include only DDL (CREATE, ALTER, etc.) or DML (INSERT, UPDATE, etc.) statements.
  • For more information please refer to the About the MariaDB Audit Plugin page. The plugin is …

MySQL 5.5.42 was recently released (it is the latest MySQL 5.5, is GA), and is available for download here:

http://dev.mysql.com/downloads/mysql/5.5.html

This release, similar to the last 5.5 release, is mostly uneventful.

There were only 3 “Functionality Added or Changed” bugs this time, all related to SSL, and only 9 bugs overall fixed.

Out of the 9 bugs, there were 2 InnoDB bugs, and 1 replication bug, all of which seemed rather minor or obscure. Here are the ones worth noting:

• Support for the SSL 2.0 and SSL 3.0 protocols has been disabled because they provide weak encryption. (Bug #19820550, Bug #19921150)
• yaSSL was upgraded to version 2.3.7. (Bug #19695101, Bug #20201864)
• The valid date range of the SSL certificates in mysql-test/std_data has been extended to the year 2029. (Bug …

The CVE-2015-0204 FREAK SSL vulnerability abuses intentionally weak “EXPORT” ciphers which could be used to perform a transparent Man In The Middle attack. (We seem to be continually bombarded with not only SSL vulnerabilities but the need to name vulnerabilities with increasing odd names.)

Is your server vulnerable?

This can be tested using the following GIST

If the result is 0; the server is not providing the EXPORT cipher; and as such is not vulnerable.

Is your client vulnerable?

Point your client to https://oneiroi.co.uk:4443/test if this returns “Vulnerable” then the client is vulnerable, if you find a connection error your client should not be vulnerable for example:

root@host:/tmp$ openssl …