Over the last year there has been alot of work done to instrument MySQL with static dtrace probes. The mysql provider first became available in MySQL 6.0.8 but required a build with the --enable-dtrace flag to enable it. Starting with MySQL 5.4 the mysql provider and it's static probes are now enabled by default and ready to be used on Solaris 10, OpenSolaris and Mac OS X.

The static probes in MySQL 5.4 have been designed to follow the execution path of a query

with the level getting deeper as the query execution proceeds. However the probes are implemented so that you don't have to traverse the entire hierarchy to get the information you want.

They are also implemented in sets. The -start probe exposes pertinent information such as the query text. The -done probe returns the status of the probe operation. With probe sets time spent within an operation can be captured.

Check out MC Brown's …

Over the last year there has been alot of work done to instrument MySQL with static dtrace probes. The mysql provider first became available in MySQL 6.0.8 but required a build with the --enable-dtrace flag to enable it. Starting with MySQL 5.4 the mysql provider and it's static probes are now enabled by default and ready to be used on Solaris 10, OpenSolaris and Mac OS X.

The static probes in MySQL 5.4 have been designed to follow the execution path of a query

with the level getting deeper as the query execution proceeds. However the probes are implemented so that you don't have to traverse the entire hierarchy to get the information you want.

They are also implemented in sets. The -start probe exposes pertinent information such as the query text. The -done probe returns the status of the probe operation. With probe sets time spent within an operation can be captured.

Check out MC Brown's …

A little while ago, I was the brave soul tasked with making sure Drizzle was working properly and passing all tests on Solaris and OpenSolaris. Brian recently blogged about some of the advantages of also running on Solaris and the SunStudio compilers - more warnings from the compiler is a good thing. Many kudos goes to Monty Taylor for being the brave soul who fixed most of the compiler warnings (and for us, warnings=errors - so we have to fix them) for the SunStudio compilers before I got to making te tests work.

So, I got to the end of it all and got pointed to an OpenSolaris x86 box where the drizzleslap test was timing out. The timeout for tests is some amazingly long amount of time - 15 minutes. All the drizzle-test-run tests are rather short tests.

To make running the tests quick, I usually LD_PRELOAD …

The Bangalore MySQL User Group is having a meetup this Saturday- 21 March. Please RSVP if you are coming.

We have the following sessions planned:

1. MySQL Query Analyzer -- How to optimize queries using query analyzer-  by Thava Alagu, Sun Microsystems
   
2. Using MySQL + DTrace -- By Amit Saha, Sun Microsystems, this session will be derived mainly from my article.
   

See you there!

The Bangalore MySQL User Group is having a meetup this Saturday- 21 March. Please RSVP if you are coming.

We have the following sessions planned:

1. MySQL Query Analyzer -- How to optimize queries using query analyzer-  by Thava Alagu, Sun Microsystems
   
2. Using MySQL + DTrace -- By Amit Saha, Sun Microsystems, this session will be derived mainly from my article.
   

See you there!

So, if there is no way to flush status variables of a server, one could use dtrace (and run SHOW GLOBAL STATUS ;-)

#!/usr/sbin/dtrace -Fws
int *zero;
BEGIN { zero=alloca(4); *zero=0; }
pid$target:mysqld:add_to_status*:1b {
        copyout(zero,uregs[R_ECX],4);
        copyout(zero,uregs[R_EDX],4);
}

P.S. This is just simple proof of concept, that can warp counters back, ignore some variables, and eat babies. Code position and registers are architecture, version and build dependent.
P.P.S. I’m giving dtrace talk at mysql conference as well (yay plugs ;-)

.. is up on MySQL Developer Zone at http://dev.mysql.com/tech-resources/articles/getting_started_dtrace_saha.html

Have a comment on the quality, or the clarity or the usefulness? Let me know!

Many thanks to Giuseppe, Lenz, Martin MC Brown and Aaron for helping in various ways.

.. is up on MySQL Developer Zone at http://dev.mysql.com/tech-resources/articles/getting_started_dtrace_saha.html

Have a comment on the quality, or the clarity or the usefulness? Let me know!

Many thanks to Giuseppe, Lenz, Martin MC Brown and Aaron for helping in various ways.

Static probes are being gradually integrated into MySQL. As of MySQL 6.0.9, there are around 55 static probes. To use the static probes, you will have to supply an extra option to the configure script, --enable-dtrace. After the build is over, start mysqld. Now open a terminal, and type $pfexec dtrace -l | grep mysql. You should see something like this:

135 mysql23509            mysqld __1cQdispatch_command6FnTenum_server_command_pnDTHD_pcI_b_ command-done
  136 mysql23509            mysqld __1cQdispatch_command6FnTenum_server_command_pnDTHD_pcI_b_ command-start
  137 mysql23509            mysqld __1cQclose_connection6FpnDTHD_Ib_v_ connection-done
  138 mysql23509            mysqld             handle_one_connection connection-start
  139 mysql23509            mysqld __1cMmysql_delete6FpnDTHD_pnKTABLE_LIST_pnEItem_pnLst_sql_list_LXb_b_ delete-done
  140 mysql23509            mysqld __1cHhandlerNha_delete_row6MpkC_i_ …