Today’s episode is all about Valgrind – from the pro’s to the con’s, from the why to the how! This episode will be of interest to anyone who is or wants to work with Valgrind on a regular or semi-regular basis.

1. Pro’s/Why
2. Con’s
3. How
   1. Using the latest version
      sudo [yum/apt-get] install valgrind
      #OR#
      sudo [yum/apt-get] remove valgrind
      sudo [yum/apt-get] install bzip2 glibc*
      wget http://valgrind.org/downloads/valgrind-3.10.1.tar.bz2
      tar -xf valgrind-3.10.1.tar.bz2; cd valgrind-3.10.1
      ./configure; make; sudo make install
      valgrind –version # This should now read 3.10.1
   2. VGDB (cd ./mysql-test)
      ./lib/v1/mysql-test-run.pl –start-and-exit –valgrind –valgrind-option=”–leak-check=yes”
      –valgrind-option=”–vgdb=yes” …

Execute “Show Engine InnoDB Status;” query analyze the result in “Transaction” section, find out problematic queries.

Now next step is to how to avoid this problem, and here is a solution:

Deadlocks are a classic problem in transactional databases, but they are not dangerous unless they are so frequent that you cannot run certain transactions at all. Normally, you must write your applications so that they are always prepared to re-issue a transaction if it gets rolled back because of a deadlock.

• Always be prepared to re-issue a transaction if it fails due to deadlock. Deadlocks are not dangerous. Just try again.
• Keep transactions small and short in duration to make them less prone to collision.

Reference :  …

It mentions in the message that you can try to repair it. Also, if you look at the actual FILEPATH you get, you can find out more:

• if it is something like /tmp/#sql_actor_return it means that MySQL needs to create a temporary table because of the query size. It stores it in /tmp, and that there is not enough space in your /tmp for that temporary table. increase the tmp_table_size variable and /tmp/ partition size
• If it contains the name of an actual table instead, it means that this table is very likely corrupted and you should repair it using REPAIR TABLE

If a table-full error occurs, it may be that the disk is full or that the table has reached its maximum size. The effective maximum table size for MySQL databases is usually determined by operating system constraints on file sizes, not by MySQL internal limits.

Limits on Table size : The following table lists some examples of operating system file-size limits. This is only a rough guide and is not intended to be definitive.

If you do encounter a full-table error, there are several reasons why it might have occurred:

• The disk might be full.
• The InnoDB storage engine maintains InnoDB tables within a tablespace that can be created from several files. This enables a table to exceed the maximum individual file size , check InnoDB tablespace (ibdata1)
• You are using MyISAM tables on an operating …

One day on production server I encountered this error message, So I found out a solution for it as:

There are multiple reasons, listed below:

1. You’ve run out of memory available to MySQL.This is the most likely problem you’re facing. Each connection in MySQL’s connection pool requires memory to function, and if this resource is exhausted, no further connections can be made. Of course, the memory footprints and maximum packet sizes of various operations can be tuned in your equivalent to my.cnf if you discover this to be an issue.

You can calculate MySQL memory using this tool – http://www.mysqlcalculator.com/

This shows maximum size a MySQL should use in your environment, in my case it’s a dedicated MYSQL …

When a new version of MySQL appears, the first source of information for the brave experimenter is a page in the manual named What is new in MySQL X.X, also known as MySQL in a nutshell. For MySQL 5.7, the in-a-nutshell page lists quite a lot of changes. In that page, the list of removed features is enough to send a chill down the spine of most any DBA. Some of the items in the deprecation section are removals in disguise, as they require immediate, rather than delayed, action to use the new version with existing application (SET …

This is getting more and more common, so I wanted to provide the steps required to get LDAP authentication working with MariaDB PAM plugin.

Unless you’re already familiar with setting up the MariaDB PAM plugin, I’d first recommend getting this to work with a standard Linux user (steps 1-4), then once all is working fine, progress to the LDAP users (steps 5-10). (And if you do not want to test this for the Linux user account, then you may skip steps #2 and #3.)

1. Enable plugin by running the following from the command line client:

   INSTALL SONAME 'auth_pam';

   You should see an entry like this afterward in SHOW PLUGINS:

       | pam | ACTIVE | AUTHENTICATION | auth_pam.so | GPL |

2. Create the mysql user account (note it does not have a password, as it will obtain this from your Linux user, and eventually the LDAP account) and provide it with the GRANTS you want it to …

I’ve had a look at a preview release of MySQL 5.7.8, some time before it became available to the general public (perks and duties of an Oracle ACE) and I found a few interesting things among the release notes and the tarball itself:

• There is a new tool named mysqlpump, which is intended as a replacement for mysqldump, with parallel processing, compression, progress watch, the long awaited ability of excluding databases or tables, and more.
• The json functionality has been fished out from the labs and added to the main distribution.

The MySQL Development team is very happy to announce that MySQL 5.7.8, the second 5.7 Release Candidate (RC2), is now available for download at dev.mysql.com (use the “Development Releases” tab).

We have fixed over 500 bugs in 5.7.8. This is on top of what we delivered in 5.7.7 and on top of bug fixes up-merged from 5.6.…

Percona is glad to announce the release of Percona XtraBackup 2.2.12 on August 3, 2015. Downloads are available from our download site or Percona Software Repositories.

Percona XtraBackup enables MySQL backups without blocking user queries, making it ideal for companies with large data sets and mission-critical applications that cannot tolerate long periods of downtime. Offered free as an open source solution, Percona XtraBackup drives down backup costs while providing unique features for MySQL backups.

Bugs Fixed:

• Percona XtraBackup would segfault during the prepare …