Hacking MySQL Source improvements

Further to my earlier post Hacking MySQL Source (in a good way) in which I was having a compilation problem when re-compiling MySQL source (i.e. tt worked the first build, but failed on subsequent re-compiles, even with no changes).
I’ve been able to solve my re-compiling issue, with special thanks to Jan Kenschke of MySQL AB, who was near during the MySQL Quiz Show.

As suspected, there is no need to re-run the ./BUILD/compile-pentium-debug command as this cleans, a simple make command is sufficient (I needed to confirm no other command args where needed). By doing this, it also better highlighted the actual error, where previously is wasn’t. I didn’t keep a copy of the error, but in effect I needed to do the following in order to successfully recompile.

su - mysqldev
cd mysql-5.1.10-beta-nightly-20060413
touch mysql-test/std_data/client-key.pem
touch mysql-test/std_data/client-cert.pem
touch mysql-test/std_data/cacert.pem
touch mysql-test/std_data/server-cert.pem
touch mysql-test/std_data/server-key.pem
make
# Success

I can’t answer why I had to do this manually (create these cert permissions), and why some level of make doesn’t (or does but I don’t know the command), but it works, and right now that’s important. Hopefully a MySQL guru can enlightment me.

From here, I was able to test as I’d written previously. I just need to confirm my changes work before reporting back, as well as providing some guidelines for debugging with gdb.

Tagged with: Compiling Databases General MySQL MySQL Users Conference 2006

Producing Alternative Means statistics with SQL

MySQL’s built-in AVG() computes the arithmetic mean — the sum divided by the count. That is the right default for many questions, but it is not always the right measure of central tendency.

Extending MySQL Capabilities with UDFs, Plugins and Components

MySQL offers three different approaches to extending the SQL capabilities with the default product you download and install. These are: User Defined Function (UDF) MySQL Manual MySQL Plugin MySQL Manual MySQL Component MySQL Manual For the purposes of this post I will be using the current LTS version MySQL 8.

Producing One-Sample Z-Test statistics with SQL

The one-sample Z-test determines whether a sample mean differs significantly from a known population mean when the population standard deviation is also known. It is the appropriate test when the population parameters are established — quality control benchmarks, national averages, long-run process measurements — and you want to evaluate whether a new sample is consistent with them.