Some time ago I wrote about MySQL 5.5 semi-synchronous replication. Since then, I have wanted to benchmark the overhead of semi-synchronous replication with a decent server. Now the occasion presented itself, thanks to some related business that I had to benchmark, and thus I did a few simple runs with and without semi-synchronous replication enabled, to see the impact of this feature on performance. If you haven't read the article on semi-synchronous replication, the bottom line is that, with this feature enabled, the master waits until at least one slave has acknowledged receipt for the data before returning a positive result to the client. This means that for each commit there are two network calls between master and slave. My gut feeling was that this feature would be costly in terms of query response time, although I was not prepared to …[Read more]
A few days ago I saw an article about Semi-Synchronous Replication in MySQL 5.5. It
asks questions, and doesn't give answers beyond gut feeling. So I
thought that I would do some practical testing of this new
Before we go that way, though, let's revisit the theory.
How semi-synchronous replication works
Figure 1. A transaction with regular replication
With regular replication, you send a transaction to the master (1). When the
COMMIT is received, the master
executes it (2), and if successful it logs the transaction to the
binary log (3). The the master answers the client request (4)
with a successful result. In the meantime, the slaves replicate
the record (5).
What happens if the master crashes after point #4 and before a slave has had a chance of getting the data in point #5?
The latest release of MySQL Sandbox, 3.0.12, has integrated plugin
installation features, as mentioned in my previous post.
Not only that. This version has also more tests, fixes a couple of bugs, and introduces basic instrumentation. Now each script released with MySQL Sandbox, and every one that the Sandbox itself installs, can leave a trail in a file.
Let's start with the plugin. The documentation has been updated to cover this new feature. And 27 new tests give me some confidence that it …
So I told myself "I wish I had a tool that installed plugins instantly and painlessly, the way MySQL Sandbox installs a server.
There you go. So yesterday I had enough of suffering and have put together an installation script that does a good job of installing several plugins with little or no effort.
OverviewHow does it work? For now, it's a separate script, but it will soon end into SBtool, the Sandbox tool.
Plugins need different operations, and the difficult part is finding a clear way of …
Some time go, we announced a new release model for MySQL. As all new things, it had some initial hiccups (with MySQL 5.4 we were still getting acquainted with the new model), but now it seems to be in full swing.
By the time you read these lines, MySQL 5.5 will be available. If the mirrors aren't seeded yet, the impatient can compile and use the new version from the launchpad source tree..
OverviewWhat's this new …[Read more]