Thursday Mar 12, 2015

Oracle Linux 7.1 and MySQL 5.6

Yesterday we released Oracle Linux 7 update 1. The individual RPM updates are available from both public-yum (our free, open, public yum repo site) and Oracle Linux Network. The install ISOs can be downloaded from My Oracle Support right away and the public downloadable ISOs will be made available in the next few days from the usual e-delivery site. The ISOs will also, as usual, be mirrored to other mirror sites that also make Oracle Linux freely available.

One update in Oracle linux 7 update 1 that I wanted to point out is the convenience of upgrading to MySQL 5.6 at install time. Oracle Linux 7 GA includes MariaDB 5.5 (due to our compatibility commitment in terms of exact packages and the same packages) and we added MySQL 5.6 RPMs on the ISO image (and in the yum repo channels online). So while it was easy for someone to download and upgrade from MariaDB 5.5 to MySQL 5.6 there was no install option. Now with 7.1 we included an installation option for MySQL. So you can decide which database to install in the installer or through kickstart with @mariadb or @mysql as a group. Again, MariaDB 5.5 is also part of Oracle Linux 7.1 and any users that are looking for strict package compatibility will see that we are very much that. All we have done is make it easy to have a better alternative option (1) conveniently available and integrated (2) without any compatibility risks whatsoever so you can easily run the real standard that is MySQL. A bug fix if you will.

I have a little screenshot available here.

Enjoy.

Thursday Jul 31, 2014

MySQL 5.6.20-4 and Oracle Linux DTrace

The MySQL team just released MySQL 5.6.20. One of the cool new things for Oracle Linux users is the addition of MySQL DTrace probes. When you use Oracle Linux 6, or 7 with UEKr3 (3.8.x) and the latest DTrace utils/tools, then you can make use of this. MySQL 5.6 is available for install through ULN or from public-yum. You can just install it using yum.

# yum install mysql-community-server

Then install dtrace utils from ULN.

# yum install dtrace-utils

As root, enable DTrace and allow normal users to record trace information:

# modprobe fasttrap
# chmod 666 /dev/dtrace/helper

Start MySQL server.

# /etc/init.d/mysqld start

Now you can try out various dtrace scripts. You can find the reference manual for MySQL DTrace support here.

Example1

Save the script below as query.d.

#!/usr/sbin/dtrace -qws
#pragma D option strsize=1024


mysql*:::query-start /* using the mysql provider */
{

  self->query = copyinstr(arg0); /* Get the query */
  self->connid = arg1; /*  Get the connection ID */
  self->db = copyinstr(arg2); /* Get the DB name */
  self->who   = strjoin(copyinstr(arg3),strjoin("@",
     copyinstr(arg4))); /* Get the username */

  printf("%Y\t %20s\t  Connection ID: %d \t Database: %s \t Query: %s\n", 
     walltimestamp, self->who ,self->connid, self->db, self->query);

}

Run it, in another terminal, connect to MySQL server and run a few queries.

# dtrace -s query.d 
dtrace: script 'query.d' matched 22 probes
CPU     ID                    FUNCTION:NAME
  0   4133 _Z16dispatch_command19enum_server_commandP3THDPcj:query-start 2014 
    Jul 29 12:32:21 root@localhost	  Connection ID: 5 	 Database:  	 
    Query: select @@version_comment limit 1

  0   4133 _Z16dispatch_command19enum_server_commandP3THDPcj:query-start 2014 
    Jul 29 12:32:28 root@localhost	  Connection ID: 5 	 Database:  	 
    Query: SELECT DATABASE()

  0   4133 _Z16dispatch_command19enum_server_commandP3THDPcj:query-start 2014 
    Jul 29 12:32:28 root@localhost	  Connection ID: 5 	 Database: database 	 
    Query: show databases

  0   4133 _Z16dispatch_command19enum_server_commandP3THDPcj:query-start 2014 
    Jul 29 12:32:28 root@localhost	  Connection ID: 5 	 Database: database 	 
    Query: show tables

  0   4133 _Z16dispatch_command19enum_server_commandP3THDPcj:query-start 2014 
    Jul 29 12:32:31 root@localhost	  Connection ID: 5 	 Database: database 	 
    Query: select * from foo

Example 2

Save the script below as statement.d.

#!/usr/sbin/dtrace -s

#pragma D option quiet

dtrace:::BEGIN
{
   printf("%-60s %-8s %-8s %-8s\n", "Query", "RowsU", "RowsM", "Dur (ms)");
}

mysql*:::update-start, mysql*:::insert-start,
mysql*:::delete-start, mysql*:::multi-delete-start,
mysql*:::multi-delete-done, mysql*:::select-start,
mysql*:::insert-select-start, mysql*:::multi-update-start
{
    self->query = copyinstr(arg0);
    self->querystart = timestamp;
}

mysql*:::insert-done, mysql*:::select-done,
mysql*:::delete-done, mysql*:::multi-delete-done, mysql*:::insert-select-done
/ self->querystart /
{
    this->elapsed = ((timestamp - self->querystart)/1000000);
    printf("%-60s %-8d %-8d %d\n",
           self->query,
           0,
           arg1,
           this->elapsed);
    self->querystart = 0;
}

mysql*:::update-done, mysql*:::multi-update-done
/ self->querystart /
{
    this->elapsed = ((timestamp - self->querystart)/1000000);
    printf("%-60s %-8d %-8d %d\n",
           self->query,
           arg1,
           arg2,
           this->elapsed);
    self->querystart = 0;
}

Run it and do a few queries.

# dtrace -s statement.d 
Query                                                        RowsU    RowsM    Dur (ms)
select @@version_comment limit 1                             0        1        0
SELECT DATABASE()                                            0        1        0
show databases                                               0        6        0
show tables                                                  0        2        0
select * from foo                                            0        1        0
About

Wim Coekaerts is the Senior Vice President of Linux and Virtualization Engineering for Oracle. He is responsible for Oracle's complete desktop to data center virtualization product line and the Oracle Linux support program.

You can follow him on Twitter at @wimcoekaerts

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