Linux CPU stress testing sample script

for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 33 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100; do while : ; do : ; done & done

for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 33 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 ; do while : ; do : ; done & done

x="x" ; while : ; do x=$x$x ; echo -n "." ; done

for i in `seq 64`; do perl -e '$z=time()+(10*60); while (time()<$z) { $j++; $sqrt = sqrt($j) for (1..9999); }' & done

fulload() { dd if=/dev/zero of=/dev/null | dd if=/dev/zero of=/dev/null | dd if=/dev/zero of=/dev/null | dd if=/dev/zero of=/dev/null & }; fulload; read; killall dd

Create bigfile:
base64 /dev/urandom | head -c 4000000 > 4mb.txt

SQL Joins

Codeproject has this image which explains the simple basics of SQL joins, taken from: http://www.codeproject.com/KB/database/Visual_SQL_Joins.aspx

ERROR 1820 (HY000): You must SET PASSWORD before executing this statement

MySQL 5.6 added comprehensive password security mechanism how password and internally handled and encrypted. One major feature is auto encrypted password generation when mysql first time installed on your system. you can find the encrypted password in /root/.mysql_secret. Once you are into mysql using encrypted password you will get this error until unless root password is not set :

SET PASSWORD = PASSWORD('new_password');

Here is how the error looks like:

-bash-4.1$ mysql -uroot -p

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 8

Server version: 5.6.19-enterprise-commercial-advanced

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;

ERROR 1820 (HY000): You must SET PASSWORD before executing this statement

Just reset the password and you should be able login on next attempt:

-bash-4.1$ mysql -uroot -p

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 8

Server version: 5.6.19-enterprise-commercial-advanced

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;

ERROR 1820 (HY000): You must SET PASSWORD before executing this statement

mysql> SET PASSWORD = PASSWORD('newpassword');

Query OK, 0 rows affected (0.00 sec)

mysql>

mysql>

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

mysql> exit

Bye

-bash-4.1$ mysql -uroot -p

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 9

Server version: 5.6.19-enterprise-commercial-advanced MySQL Enterprise Server - Advanced Edition (Commercial)

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;

+--------------------+

| Database           |

+--------------------+

| information_schema |

| mysql              |

| performance_schema |

| test               |

+--------------------+

4 rows in set (0.00 sec)

“The program can’t start because MSVCR100.dll is missing from your computer.” error on Windows

I was installing a software on windows 2008R2 64 bit edition and ran into this error.

"The program can't start because MSVCR100.dll is missing from your computer. Try reinstalling the program to fix this problem"

After doing some online research I figured the Microsoft Visual C++ Redistributable package requires installed prior installing my desired installation.

This Redistribution package is available on microsoft website. Here's the link for both x86 or x64 edition.

32 bit: http://www.microsoft.com/download/en/details.aspx?id=5555
64 bit: http://www.microsoft.com/download/en/details.aspx?id=14632

What's Your Favorite Feature of SQL Server 2012?

MySQL Import Error 1153 - Got a packet bigger than 'max_allowed_packet' bytes

Today I was importing a MySQL database and ran into this Error “Error 1153 - Got a packet bigger than 'max_allowed_packet' bytes”.

Basically , When you dump table data from MySQL, you may end up pulling a large chunk of data and it may exceed the MySQL client’s max_allowed_packet variable. If that happens, you might catch an error like this:

mysqldump: Error 2020: Got packet bigger than 'max_allowed_packet' bytes when dumping table `tablename` at row: 1627

The default max_allowed_packet size is 25M, and you can adjust it for good within your my.cnf by setting the variable in a section for mysqldump:

OR

The fix is to increase the MySQL daemon’s max_allowed_packet. You can do this to a running daemon by logging in as Super and running the following commands. Keeping the session open create a 2nd session in which to run the import.

mysql> set global net_buffer_length=1000000;
Query OK, 0 rows affected (0.00 sec)

mysql> set global max_allowed_packet=1000000000;
Query OK, 0 rows affected (0.00 sec)

Keep the mysql prompt open, and run your command-line SQL execution on a second terminal..

MySQL : Monitor live MySQL queries

You can run the mysql command "show processlist" to see what queries are being processed at any given time, but that probably won't achieve what you're hoping for as this won’t show the whole SQL text.

Here are the steps to dump sql into a file for analysis.

mysql> SHOW VARIABLES LIKE "general_log%";

+------------------+----------------------------+

| Variable_name    | Value                      |

+------------------+----------------------------+

| general_log      | OFF                        |

| general_log_file | /var/run/mysqld/mysqld.log |

+------------------+----------------------------+

Turn on the SQL Logging and go to the general_log_file location.

mysql> SET GLOBAL general_log = 'ON';

Do your queries (on any db). Grep or otherwise examine /var/run/mysqld/mysqld.log

Then don't forget to disable the general_log parameter to OFF.

mysql> SET GLOBAL general_log = 'OFF';

or the performance will plummet and your disk will fill!