Welcome to MySQL QA Episode 3: “Debugging: GDB, Backtraces, Frames and Library Dependencies”In this episode you’ll learn how to use debugging tool GDB. The following debugging topics are covered:
I noticed that in the latest release of Percona XtraDB Cluster (PXC), the behavior of wsrep_RSU_method changed somewhat. Prior to this release, the variable was GLOBAL only, meaning to use it you would:mysql> set GLOBAL wsrep_RSU_method='RSU';
mysql> ALTER TABLE ...
mysql> set GLOBAL wsrep_RSU_method='TOI';This had the (possibly negative) side-effect that ALL DDL’s issued on this node would be affected by the setting while in RSU mode.
Quite often, especially for benchmarks, I am trying to limit available memory for a database server (usually for MySQL, but recently for MongoDB also). This is usually needed to test database performance in scenarios with different memory limits. I have physical servers with the usually high amount of memory (128GB or more), but I am interested to see how a database server will perform, say if only 16GB of memory is available.
Like any good, thus lazy, engineer I don’t like to start things manually. Creating directories, configuration files, specify paths, ports via command line is too boring. I wrote already how I survive in case when I need to start MySQL server (here). There is also the MySQL Sandbox which can be used for the same purpose.