Search Results for: mysql command line

Logging your MySQL command line client sessions

Baron recently wrote about very helpful but often forgotten about “Pager” feature of command line client. There is another one which falls into the same list – the –tee option. Specifying –tee=/path/to/file.log you can get all session content (everything typed in and printed out) stored in the log file. Quite handy for example to keep […]

MySQL 5.1 Command line client improvements

Just found this little handy feature today:

So now if you press CTRL-C MySQL Command Line Client will not exit but will terminate query being executed. This is great as so many queries assumed CTRL-C would also abort running query in previous MySQL versions and I’ve seen many monstrous queries left running without noticing […]

Why base64-output=DECODE-ROWS does not print row events in MySQL binary logs

Lately I saw many cases when users specified option --base64-output=DECODE-ROWS  to print out a statement representation of row events in MySQL binary logs just to get nothing. Reason for this is obvious: option --base64-output=DECODE-ROWS  does not convert row events into its string representation, this is job of option --verbose . But why users mix these […]

Multi-source replication in MySQL 5.7 vs Tungsten Replicator

MySQL 5.7 comes with a new set of features and multi-source replication is one of them. In few words this means that one slave can replicate from different masters simultaneously. During the last couple of months I’ve been playing a lot with this trying to analyze its potential in a real case that I’ve been […]

MySQL QA Episode 8: Reducing Testcases for Engineers: tuning

Welcome to MySQL QA Episode 8: Reducing Testcases for Engineers: tuning Advanced configurable variables & their default/vanilla settings FORCE_SKIPV FORCE_SPORADIC TIMEOUT_COMMAND & TIMEOUT_CHECK MULTI_THREADS MULTI_THREADS_INCREASE QUERYTIMEOUT STAGE1_LINES SKIPSTAGE FORCE_KILL Some examples FORCE_SKIPV/FORCE_SPORADIC TIMEOUT_COMMAND/TIMEOUT_CHECK Full-screen viewing @ 720p resolution recommended.

Using Cgroups to Limit MySQL and MongoDB memory usage

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 […]

MySQL 5.7 key features

The other day I was discussing new features of MySQL 5.7 with a Percona Support customer. After that conversation, I thought it would be a good idea to compile list of important features of MySQL 5.7. The latest MySQL 5.7.6 release candidate (RC) is out and is packed with nice features. Here’s a list of […]

Profiling MySQL queries from Performance Schema

When optimizing queries and investigating performance issues, MySQL comes with built in support for profiling queries aka SET profiling = 1; . This is already awesome and simple to use, but why the PERFORMANCE_SCHEMA alternative? Because profiling will be removed soon (already deprecated on MySQL 5.6 ad 5.7); the built-in profiling capability can only be enabled per session. This […]