I just posted this to the MySQL Internals mailing list: Hi all, Like many of you, I’m disappointed that the bzr trees for MySQL are out of sync with the tarball source and binary releases from Oracle. Since Oracle has been silent on this, and this is a recurring problem, I’ve decided to attempt to […]
Where does software go while it’s waiting for release? The answer is: our experimental repository! For anywhere from a few days to a week before we release them, we stage our software releases in the TESTING download area and in separate software repositories for Debian/Ubuntu and CentOS/RHEL. This is so that we can co-ordinate things such […]
Percona Live London starts on Monday, so this is the last in the series of free-Percona-Live tickets we’ll give away. But first — have you ever wondered what servers are in your MySQL replication hierarchy? We have, too. As consultants, a lot of times we need to get a quick overview of the whole replication […]
HandlerSocket has really generated a lot of interest because of the dual promises of ease-of-use and blazing-fast performance. The performance comes from eliminating CPU consumption. Akira Higuchi’s HandlerSocket presentation from a couple of months back had some really good profile results for libmysql versus libhsclient (starting at slide 15). Somebody in the audience at Percona […]
I’ve heard this question a lot, but never thought to blog about the answer. “Is there a performance difference between putting the JOIN conditions in the ON clause or the WHERE clause in MySQL?” No, there’s no difference. The following queries are algebraically equivalent inside MySQL and will have the same execution plan.
SELECT * FROM A, B WHERE A.ID = B.ID;
SELECT * FROM A JOIN B ON A.ID = B.ID;
SELECT * FROM A JOIN B USING(ID);
This is a fun question I’ve been wanting to test for some time.Â How much overhead does a trivial WHERE clause add to a MySQL query?Â To find out, I set my InnoDB buffer pool to 256MB and created a table that’s large enough to test, but small enough to fit wholly in memory:
I believe we wrote about this before, but this topic popups again and again. Today I’ve read opinion that if we have clause WHERE has_something=1 we should have index on column has_something (the column has two values 0 and 1). In reality the right answer is not so simple.
As you might noticed there are no recent MySQL Community versions available for download from MySQL Download Area This applies both to binaries (which is expected with new polices) but also to the source files which were promised to be available. So what is if you would like to use recent MySQL code while staying […]
I was fortunate to attend an Ops discussion about databases at the OpenStack Summit Atlanta this past May as one of the panelists. The discussion was about deadlock issues OpenStack operators see with Percona XtraDB Cluster (of course this is applicable to any Galera-based solution). I asked to describe what they are seeing, and as […]
There are a lot of tools that generate test data. Many of them have complex XML scripts or GUI interfaces that let you identify characteristics about the data. For testing query performance and many other applications, however, a simple quick and dirty data generator which can be constructed at the MySQL command line is useful. […]