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I remember when MySQL was spreading rapidly, mostly due to its ease of use. That was long time ago, apparently. Now we are entering the dark ages of obscure settings, or so it seems, reading some MySQL Cluster setting definitions.
Quoting from the the manual:

TimeBetweenLocalCheckpoints

This parameter is an exception in that it does not specify a time to wait before starting a new local checkpoint; rather, it is used to ensure that local checkpoints are not performed in a cluster where relatively few updates are taking place. In most clusters with high update rates, it is likely that a new local checkpoint is started immediately after the previous one has been completed.

The size of all write operations executed since the start of the previous local checkpoints is added. This …

Have you seen recent eWeek benchmarks which test OpenSource stacks and compare them to .NET ? Here is what was compared and here are results.

Results make me ask number of questions - why WAMP would perform 6 times better than LAMP ? Why Python would be faster than PHP on Windows but slower on Linux ? Without having such basic questions answered I can't accept results as valid. If you run benchmark and something unexpected pops up drill it down - quite frequently it would be configuration problem, bug or something similar.

Well, this is however not my main concern with this benchmark. Here is to start:

No Specifications - Good benchmark starts with specifications. What …

MySQL on GNU/Linux appears to be able to either run multiple processes, or one process and multiple threads. We've noticed a significant CPU penalty for multiple processes, probably from the context switching overhead. The trouble was, one of our servers wouldn't use threads; it wanted to use multiple processes. This article explains how we got it to use threads instead.

One needs to be very careful before deleting files as once deleted the files are gone for good. A friend of mine today called as MySQL was failing to start on his server. Earlier when "cleaning" his server, he had deleted binary log files without fully understanding their role. When I logged in to his server, I noticed the following errors:

060716 17:21:53  mysqld started
060716 17:21:53  InnoDB: Started; log sequence number 0 1736000119
/usr/sbin/mysqld: File './mysql-bin.000002' not found (Errcode: 2)
060716 17:21:53 [ERROR] Failed to open log (file './mysql-bin.000002', errno 2)
060716 17:21:53 [ERROR] Could not open log file
060716 17:21:53 [ERROR] Can't init tc log
060716 17:21:53 [ERROR] Aborting

060716 17:21:53  InnoDB: Starting shutdown...
060716 17:21:55  InnoDB: Shutdown completed; log sequence number 0 1736000119
060716 17:21:55 [Note] /usr/sbin/mysqld: Shutdown complete
 …

Hi, what follows are my personal thoughts after reading Dmitry Yemanov's comments to a great poll posted at Firebirdnews about the features people would like to see implemented.
Quote:

Well, since Intel and AMD are massively going for multicore architectures on the desktop and SMP servers are more and more common in datacenters I wouldn't place this in a whishlist, …

I fixed a serious BC issue that I introduced in the last releases of the MySQL drivers, that would cause issues with servers that do not support InnoDB. I switched to forcing the InnoDB table handler. The fix is to simply not force any table handler and use the server default. There were also some minor bug fixes in several of the other drivers. More importantly however I am pretty happy with the nested transaction API as well as improvements to the debug callback mechanism.

I have mentioned the nested transaction support previously. Since then we have added support for SAVEPOINTs. This feature allows you to define a savepoint within a transaction to which you can rollback to, instead of rolling back the entire transaction. By default the nested transaction API will automatically use SAVEPOINTs to give really tight control in an entirely transparent fashion.

I have also …

I've been looking at a problem with our memory cache system at work for the last week and the problem finally clicked into place.

At work I developed this really awesome benchmarking library which exports statistics from various subsystems in our robot. It works really well - too well sometimes.

Its been telling me that one of my key caches is only functioning at 20% efficiency.

This is a memcached cache which means its broken out into many small servers running 256M or 512M or memory (really whatever they can spare).

Each of these servers was reporting that they are only 70% full so therefore I don't need to add any more memory right?

Wrong. I was look at the number of stored bytes vs the total maximum amount of bytes allocated to memcached.

The problem is …