A regression in MySQL Cluster 7.0.8 and 6.3.27 has caused them to be removed from download.

Problem:
If you have a mysql server with higher node id than 49, then it will cause cluster to crash.

An updated version of MySQL Cluster 7.0.8, called 7.0.8a will be released very soon.

The Configurator has been reverted back to use 7.0.7 and 6.3.26.

Sometimes I have seen and heard about that a data node gets stuck in start phase 101.

Unfortunately it is difficult to reproduce this (found no way yet), so no bug fix is in the pipe yet.

What happens is that in sp 101, the starting data node (actually a block called SUMA) should reconnect to the mysql server and take over the event handling (sending events to the mysql server), but it never gets the reconnect to the mysql server(s). A better explanation is here :)

If you see your data node stuck here then try the following:
1) Restart the mysql servers (one by one), the data node should now start
or
2) Restart the mysql servers and restart the data node.

Only do 2) if 1) does not work.

And if you know how to reproduce - …

Jonas just wrote a patch to this bug on OPTIMIZE TABLE, and the issue that was also discussed in this blog post. Jonas also fixed this bug when he was at it.

Before, OPTIMIZE TABLE hardly freed up any pages and to defragment you had to do a rolling restart of the data nodes.

Now, there is only a 2% discrepancy between OPTIMIZE TABLE and doing a rolling restart. This is great stuff.
This will fix will make it into 6.3.26 and 7.0.7.

See below for details:

Creating two tables, t5 and t6:

CREATE TABLE `t5` (
`id` varchar(32) CHARACTER SET utf8 NOT NULL,
`name` varchar(32) …

Currently a number of users has reported upgrade issues on 6.3.x to 7.0.6 (below is an example what might happen to you).

Thus, we don't recommend you to upgrade from 6.3.x to 7.0.6 in a production system yet.
However, we are very interested in bug reports and and help with testing.
We are also of course working on fixing these issues and will keep you posted when things has improved. Sorry for the inconvenience.

Currently the "best practice" to upgrade is to:
1) backup / mysqldump
2) start cluster 7.0.6 with initial so it is completely blank
3) restore backup / load dump


ERROR 1005 (HY000): Can't create table 'test.#sql-3d25_aa905' (Errno: 140)

mysql> show warnings;
+-------+------+--------------------------------------------------------------------------+
| Level | Code | Message |
…

Over last couple of years I have ran into random MySQL crashes in production when multiple key caches were used. Unfortunately this never was frequent or critical enough issue so I could spend time creating repeatable test case and search of the bug in the MySQL database did not find anything. Recently we had this problem again and now discussed it with Monty's team - this time we found the bug for this issue.

It is no surprise why I could not find the bug easily - the bug is not really related to multiple key caches but to online key cache resize. It is just this code most actively used in case you're using multiple key caches. It is very rare one would resize single key cache in production and it only triggers crash sometimes, while if you're using multiple key caches there are often some scripts in place which adjust their size or change mappings of the tables.

…

I ran into a rather interesting situation today with a client. It seems that the mysqld daemon stopped with no errors in the error log. I ran through the obvious problems … not enough disk space, memory utilization etc and came up empty.

The server was running MySQL 4.1 on Fedora Core 5. We can save the discussion about running your database on reasonable up to date hardware and operating system for another post. Core 5 runs the GNU/Linux kernel 2.4 along with the ext3 filesystem and so the thought was in the back of my mind that it might be an issue with file size. Well, as Sun’s own documentation shows this shouldn’t be the case.

During the investigation it was uncovered that the general query log was not only enabled but 16 gigabytes in size. Aside from being so large it was absolutely useless for anything, it was the obvious culprit for …

A long standing bugAmong the many outstanding bugs for MySQL, there is one that has sparked a fierce discussion, not only in the bug report itself, but also in blogs, forums, mailing lists.
Bug #19027: MySQL 5.0 starts even with Fatal InnoDB errors was neglected for long time, until finally it got fixed, and it is available in MySQL 5.1.36.
First off, what is it about?
In short, if an engine doesn't initialize correctly, the MySQL server starts anyway, without the offending engine. Depending on how you use the failing engine, this could be either a minor annoyance or a complete disaster.
Annoyance: ARCHIVE fails to initialize, and you create tables with the default engine (usually MyISAM), and after a while you realize that the disk is filling up faster than you expected. You will find out eventually.
Disaster: ARCHIVE fails to …

This is sort of a self-documenting post, and a self-support group about ill-behaved tomcat apps. Sometimes, you have multiple nodes accesing your MySQL server (or any kind of server, for that matter) concurrently. Eventually, software in one or more of these nodes might do nasty things (you know who you are buddy:)) MySQL provides a … Continue reading iptables trick to limit concurrent tcp connections →

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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 "disable firewall <your …

Last year, Erik Ljungstrom (sensei in the #ourdelta IRC channel on Freenode) created patch for a bug Arjen identified with the handling of (among others) the open-files-limit option; the patch was first included in the OurDelta build of MySQL 5.0.67.

Now, Sun engineer Guilhem Bichot has committed the (modified) patch into the 6.0-maria tree, so it should appear in 6.0 and potentially 5.4. That’s good.

See http://bugs.mysql.com/40368 for details and history.