SPOF (i.e. Single Point of Failure) is the bane for technologists. Avoiding SPOF generally requires redundancy, and redundancy has a cost, often more then a business is prepared to pay. In the database field, I see this regularly and advise clients on how to improve availability and potential avoid disasters that can affect their business.

Today, at approximately 10:30am, the Con Edison work crew in front of my home (digging a 5″ deep trench down the road), severed multiple Time Warner Cable fibre connections. ($#&* and the lack of ownership to correct timely is another story). No Internet, no ability to work actively with clients (which I was doing), etc, etc.

As an individual that works from home, I have recognized this SPOF and have redundancy in place. That is, a Verizon MiFi HotSpot, normally used for travel, but a backup in times of Internet downtime to my home. The moral here is, one level of redundancy is often not …

MySQL management plugin for EM 12c has been long overdue. I’ve initially migrated the older plugin to EM 12c about 6 months ago, and few dozen people received this as the initial beta of the plugin. It worked OK but didn’t use any of the new 12c features, and its home page was a bit of a mess in the EM 12c Cloud Control web interface.

I’ve had lots of new features to add, but I didn’t really have much time to invest into completing them all. Finally, I decided to just finish the home page dashboard and clean it up from all unfinished new features. I did, however, finish MySQL Slave configuration and status monitoring, which was the largest gap in the the functionality of the previous plugin. There is no custom UI for MySQL slave management yet (that’s coming), but monitoring is available as standard metrics and configuration management …

PyCONs are in full swing !

Oracle will be at PyCON India with two MySQL Sessions:

• Introduction to MySQL Connector/Python  by Uma Bhat
• MySQL Utilities - Time saving scripts for DBA by Megha Singhvi

Oracle will also have a booth  so please come by !

PyCON 2013 in Santa Clara will be March 15th - 17th.
    Tutorials: March 13–14
    Main Conference: March 15–17
    Development Sprints: March 18–21

The …

I got the message in the morning today about the bug being fixed in MySQL 5.6.6…. which I reported in Early 2006 (while still being with MySQL) and running MySQL 4.1 I honestly thought this issue was fixed long ago as it was indeed pretty annoying. I must say I’m very impressed with Oracle team going and cleaning up such very old bugs. Here is a description from the bug:

If you perform  match of constant which is too large  to the column
instead of simply responding with empty set MySQL   truncates the
constant, performs the lookup  and only when  discards results:

CREATE TABLE `trunc` (
  `i` int(11) NOT NULL default '0',
  KEY `i` (`i`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8



mysql> select i,count(*) cnt from trunc  group by i order by cnt desc
limit 10;
+------------+-------+
| i          | cnt   |
+------------+-------+
| 2147483647 | 76047 |
| 1421638051 |     3 |
|  985505567 | …

Last week I wrote about our 10x insertion performance increase with MongoDB. We’ve continued our experimental integration of Fractal Tree® Indexes into MongoDB, adding support for clustered indexes.  A clustered index stores all non-index fields as the “value” portion of the index, as opposed to a standard MongoDB index that stores a pointer to the document data.  The benefit is that indexed lookups can immediately return any requested values instead of needing to do an additional lookup (and potential disk IOs) for the requested fields.

To create a clustered index you just need to add “clustering:true” as in the following example (note that version 2 indexes are Fractal Tree Indexes): …

In relation to these two posts from Justin Swanhart and Anders Karlsson about transaction isolation levels, I thought it was interesting to do a little survey to get an idea of the most commonly used isolation levels.

Note: There is a poll embedded within this post, please visit the site to participate in this post's poll. Related Posts :

• [UPDATED] Why you should go to Percona Live (London) ?
• Fatal timeout !
• …

Continuing with another blog about troubleshooting MySQL Cluster we will look at a common error message: "Too many active scans".

Now, you have already set MaxNoOfConcurrentScans=500 in your config.ini, and you can't increase it more (the max is 500), but you still get this error. Frustrating!

But looking into the code, it is not MaxNoOfConcurrentScans that sets the limitation, it is actually MaxNoOfLocalScans and the "Too many active scans" comes from the Local Query Handler of the NDB node, and that is where MaxNoOfLocalScans is used!

So what you can try to do is to actually set/increase MaxNoOfLocalScans, and if it is not set already in your config.ini, the default value is calculated as:

In 7.2.0 and later:
MaxNoOfLocalScans= tcInstances * lqhInstances * noOfDBNodes * 
                …

Why is it so important to close connections to databases if there’s no explicit need to keep them open (which usually the case)?

Symptoms

• Icinga reports high usage of allowed connections (>90%) on master MySQL server.
• No running queries or any specific in processlist. All the connections are sleeping from the same servers.
• The number of connections was 20 times more than the usual

Root cause

There was tremendous amount of queries doing “copying to tmp table” on the slaves. The connections were opened to both master and slaves and waiting for the slaves to answer the query the connections to master was kept opened. So the sleeping connections was piled up to the limit of max connections.

Lesson

1. When troubleshooting always check slaves too.
2. Close unused connections especially for masters.
3. Keep your query optimized and …

We are proud to announce the release of

MySQL Proxy 0.8.3 (alpha)

which updates MySQL Proxy for the protocol changes introduced in MySQL 5.5 and 5.6.

All users of MySQL Proxy 0.8.x are recommend to upgrade.

ChangeLog

• added network timeouts for connect, read and write operations
• --proxy-connect-timeout, --proxy-read-timeout, --proxy-write-timeout
• added IPv6 support
• added initial support for the win-auth-method and its protocol extensions (MySQL 5.5.17)
• added support for extracting the pluggable auth protocol information
• Lua-API added:
  • con.client.challenge.auth_plugin_name
  • con.client.response.auth_plugin_name
• fixed handling capability flags in the client auth response …

We are proud to announce the release of

MySQL Proxy 0.8.3 (alpha)

which updates MySQL Proxy for the protocol changes introduced in MySQL 5.5 and 5.6.

All users of MySQL Proxy 0.8.x are recommend to upgrade.

ChangeLog

• added network timeouts for connect, read and write operations - --proxy-connect-timeout, --proxy-read-timeout, --proxy-write-timeout

• added IPv6 support

• added initial support for the win-auth-method and its protocol extensions (MySQL 5.5.17)

• added support for extracting the pluggable auth protocol information - Lua-API added: - con.client.challenge.auth_plugin_name - con.client.response.auth_plugin_name

• fixed handling capability …