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Suddenly your application starts throwing "error 157" and performance degrades or is non-existing. It is easy to panic then and try all sorts of actions to get past the problem. We have seen several users doing:

• rolling restart
• stop cluster / start cluster

because they also see this in the error logs:120828 13:15:11 [Warning] NDB: Could not acquire global schema
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common_schema, revision 218 is released, with major new features, top one being server side scripting. Here are the highlights:

• QueryScript: server side scripting is now supported by common_schema, which acts as an interpreter for QueryScript code.
• Throttling for queries is now made available via the throttle() function.
• Enhancements to processlist-related views, including the new slave_hosts view.
• Inline documentation/help is available via the help() routine.
• more...

QueryScript

common_schema makes for a QueryScript implementation for MySQL. You can run server side

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Introducing QueryScript: a programming language aimed for SQL scripting, seamlessly combining scripting power such as flow control & variables with standard SQL statements or RDBMS-specific commands.

QueryScript is available fro MySQL via common_schema, which adds MySQL-specific usage.

What does QueryScript look like? Here are a few code samples:

Turn a bulk DELETE operation into smaller tasks. Throttle in between.

while (DELETE FROM archive.events WHERE ts < CURDATE() LIMIT 1000)
{
  throttle 2;
}

Convert all InnoDB tables in the 'sakila' database to compressed format:

foreach ($table, $schema, $engine: table in sakila)
{
  if ($engine = 'InnoDB')
    ALTER TABLE

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Being a MySQL DBA , one faces a common issue in replication environment -> Disk space issue on master, since the number of binary logs have increased.Now, one of the solution to this would be using expire_logs_days parameter in your mysql config file. But what if, the slave is lagging by few hours or if the slave is broken since few days and the binary logs are removed due to the parameter set. Whenever the salve comes up, it will go bonkers, knowing that the binary log where it last stopped no more exists.
I faced this issue a couple of times until I decided to automate it using a script. Herewith I am attaching the URL to my python script which can run regularly in cron.Features :

• Checks the slaves connected to the master (I have limit it to 3 for now.)
• Checks the last binary log file which is being used by the

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Maatkit is a pretty useful set of utilities for MySQL. From their site:

You can use Maatkit to prove replication is working correctly, fix corrupted data, automate repetitive tasks, speed up your servers, and much, much more.

One of the first things you can do after installing the toolkit (which may already be installed if you are running CentOS or Debian) is to run the mk-audit utility. It will give you a nice summary of your server, as well as point out potential problems in your configuration.

Here's a list of all the utilities included in Maatkit:

• mk-archiver Archive rows from a MySQL table into another table or a file.
• mk-audit Analyze, summarize and report on MySQL config, schema and operation
• mk-checksum-filter Filter

  [Read more...]

I am publishing my MySQL related bookmark collection http://www.mysqlpreacher.com/bookmarks/.

Feel free to send me links you think might be good to add in order to help others.

Remember, SHARING IS CARING!!! …. we get so much for free, why shouldn’t we give some back?

Cheers,
Darren

Just a small note to advise that Securich reached 0.1.4.
Some new tools include:
* Added Password complexity
* Enhanced `set_password` – Old password is now necessary to replace it by a new one
* Enhanced Revoke privileges to accept regexp
* Added Block user@hostname on a database level
* Added Creation of reserved usernames
* Added Help stored procedure displays help for each stored proc
* Enhanced `create_update_role` to include the removal of privilages from roles
* Enhanced `grant_priveleges` on `alltables` for a database without tables would terminate with an error instead of gracefully (now fixed)
* Added Restore user@hostname on a database level
* Removed ’show warnings’ from sql installation

The database design using workbench

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If the Cluster fails to start, what can you do and what to check?

Initial system start
If it is the first time you start up the cluster and it fails, then check the following:

• Network - Check /etc/hosts
  You should have (on the line for localhost)
  127.0.0.1 localhost
  and nothing else! Then the normal IP address host mapping follows..
  REDHAT and others can add a lot of other things to that line, and this results in that the nodes won't be able to connect to each other (they will be stuck in phase 0 or phase 1)
  
• Network - Check if you can ping the machines
  
• Network - Check if you have any firewalls enables ( e.g check with /sbin/iptables -L)
  Disable the firewall in that case. Exactly how depends on OS and Linux distribution.
  On Redhat systems, then SELinux might be enabled. Googling
  
  

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Properties:

Applicable To MySQL/Linux Server Startup Option --large-pages Scope Global Dynamic No way Possible Values True|False flag Default Value False Category Performance, Administration

Description:

This option, currently available only for Linux, if set enables the usage of large pages by MySQL. Many operating systems/system architectures support optional memory pages bigger than the default size (4 KB). Usually the large page size is 2 MB, this can be checked in the large_page_size variable in MySQL.

For applications that do a lot of memory accesses, as MySQL can, reduced TLB (Translation Lookaside Buffer) misses lead to better

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