Shantanu's Blog

Corporate Consultant

October 21, 2009

 

Look for orphan pages

In order to check if there are no junk files in the datadir, simply run the following shell script. It will list all the files from a particular directory and search if that file is referred to from any file.

#!/bin/sh

> /home/develop/orphan1.txt

for myfile in `ls -R /var/www/html/ | tr "\t" "\n"`
do

grep -R -m1 $myfile /var/www/html/* > /dev/null 2>&1
if [[ $? -ne 0 ]];then
find /var/www/html/ -name $myfile >> /home/develop/orphan1.txt
fi
done

# sort remove duplicates and remove leading /var/www/html part of file path
# sort -u /home/develop/orphan1.txt | sed 's/^\/var\/www\/html//g' > /home/develop/orphan.txt



_____

In order to find if the tables are useless, simply check the table names in the mysql general log.

for mytable in `mysql -uroot -pPassWord test -BNe"show tables"`
do
mycount=`grep -c "$mytable" mysql-gen.log`
echo "$mytable" "$mycount" >> tableReport.txt
done

_____

You can also check if the table name is used anywhere in the code.

Table list was generated using the following command...
mysql -Bse"select TABLE_NAME from information_schema.TABLES where TABLE_SCHEMA='shantanu';" > /home/develop/tblist1.txt

The following shell script generated the table list...
# cat otable.sh
#!/bin/sh
> /home/develop/orphan1.txt
for myfile in `cat tblist1.txt | tr "\t" "\n"`
do
grep -R -m1 $myfile /var/www/html/* > /dev/null 2>&1
if [[ $? -ne 0 ]];then
echo "$myfile" >> /home/develop/orphan1.txt
fi
done

disclaimer: A table can be still useful even if it does not appear in the general log if it is a part of procedure, trigger or cron.

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October 18, 2009

 

PHP security tips

avoid SQL Injection

It can happen anywhere you have a form that the user can fill in and submit.
There is a PHP function to avoid the SQL Injection attack.

$query_ok = "SELECT * FROM users WHERE username = 'mysql_real_escape_string($injection_string)'";

Real escape strings will replace all single quote and double quote character with the escaped string \

$new_user=mysql_real_escape_string($_GET["injection_string"]);

$query_ok = "SELECT * FROM mysql.user WHERE User = '" . "$new_user" ."' limit 1";
echo $query_ok;
$result=mysql_query($query_ok) or die("some errror");

_____


If you need to use SMTP server to send mail, here is a nice writeup for the same.

http://9lessons.blogspot.com/2009/10/send-mail-using-smtp-and-php.html

Labels: ,


 

Finding Database Name

In order to find out the database that is being used, you have exclude the other default DBs like mysql and test. Here is a simple shell script that will do the job.

#!/bin/sh
for dbName in `mysqlshow -uroot -pPassWord | awk '{print $2}'`
do
echo "$dbName" | egrep -v 'mysql|test|Databases|information_schema';
done

You can also echo it out on a single line like this...

echo $(mysqlshow -uroot -pPassWord | awk '{print $2}' | egrep -v 'mysql|test|Databases|information_schema|lost\+found')

Labels:


October 15, 2009

 

throwing logs to bit bucket

If you need to turn the general log or slow query log on temporarily for debugging purposes, send it to /dev/null as shown below.

ln -fs /dev/null/ /var/log/mysql/general.log

then an ls -l would show
/var/log/mysql/mysql-general.log -> /dev/null

And to turn the query log on all you need to do is:
rm /var/log/mysql/mysql-general.log

and at the mysql command prompt:
mysql> FLUSH LOGS;

The same trick can be used for enabling / disabling apache error logs.

Labels:


October 12, 2009

 

Installing standard procedures for MySQL

** Backup of Information Schema tables **
When the database has too many tables or when the innodb table space is too big, you can not run queries against information_Schema Database. It is a good idea to copy the data of those tables to a new database, for e.g. "schemaBackup". Here is the script that will do the needful.

# cat stats.sh
#!/bin/sh
mysql -e"create database if not exists schemaBackup";

for tblName in `mysql -e"show tables from information_schema"`
do
mysql -e"drop table if exists schemaBackup.$tblName;"
mysql -e"create table schemaBackup.$tblName select * from information_schema.$tblName;"
done

for tblName in `mysql -e"show tables from mysql"`
do
mysql -e"drop table if exists schemaBackup.$tblName;"
mysql -e"create table schemaBackup.$tblName select * from mysql.$tblName;"
done
_____


You can use the following line at command prompt to install all the required functions and stored procedures.

# lynx -source http://saraswaticlasses.net/yubnub/updates.txt | sed 's/information_schema/schemaBackup/g' | mysql -uroot -pPassWord mysql

If you are not using the backup Database, remove the "sed" clause.
Once the script is installed without any error, you can start calling the procedures and use the new functions.

// Show triggers
select * from mysql.SHOW_CREATE_TRIGGERS;

// create table customers with 5 columns in the test database
call mysql.createtable ('test.customers', 5);

// check if data violates foreign key constraint
call mysql.p_check_fk_constraint_violations('sakila','%');

// one liner to check foreign key violations
mysqlshow | egrep -v "(Databases|information_schema|performance_schema|mysql)" | awk '{print $2}' | sed '/^$/d' | awk '{sub($1,"mysql \-uroot \-Bse \"call mysql.p_check_fk_constraint_violations\('"'"'&'"'"','"'"'%'"'"'\)\""); print $0}' | sh

// check all DB's for data violation of foreign key
# for dbname in `mysqlshow`; do echo $dbname; mysql -e"call mysql.p_check_fk_constraint_violations('$dbname','%')"; done

// proper case
select mysql.proper('first character should be capital ');

// Normalize table with comma as delimiter
CALL mysql.normalize_table('myDB.myTable', 'uniquefield', 'ids', ',');

// list all columns
call mysql.getColumnNames('dbName', 'tableName');

// find reserved words used in DB
select a.table_schema, a.table_name, a.column_name from information_schema.columns as a inner join mysql.reserved_words as b on upper(a.column_name) = b.reserved_word;

select a.table_schema, a.table_name from information_schema.TABLES as a inner join mysql.reserved_words as b on upper(a.table_name) = b.reserved_word;

select a.table_schema from information_schema.TABLES as a inner join mysql.reserved_words as b on upper(a.table_schema) = b.reserved_word;

// list any object type for e.g. triggers from your database
select * from mysql.dba_objects where OBJECT_TYPE = 'trigger' and SCHEMA_NAME = 'dbName';

// list of redundant indexes (I_S_INDEXES: lists all indexes)
select * from mysql.I_S_REDUNDANT_INDEXES;

_____

// Add the following to bashrc so that you can simply type mysql_new to login fast.

vi ~/.bashrc
alias mysql_new='mysql -uroot -p --prompt="(\r:\m)\_mysql>" --show-warnings --tee="/home/sqltee.txt"'

alias myproxy="sh /usr/share/mysql/mysql-proxy-0.8.1-linux-rhel5-x86-64bit/bin/mysql-proxy --plugins=proxy --proxy-lua-script=/usr/share/mysql/mysql-proxy-0.8.1-linux-rhel5-x86-64bit/share/doc/mysql-proxy/failed-query.lua >> /home/failed_query.log &"

alias mysql_count='mysql -e"SELECT SUBSTRING_INDEX(host, \":\", 1) AS host_short, GROUP_CONCAT(DISTINCT USER) AS users, COUNT(*) as MYCOUNT FROM information_schema.processlist GROUP BY host_short with rollup;"'


vi ~/.bash_profile
script /home/shantanu/mylog_$(date '+%Y%m%d%H%M').log
screen -S shantanu

# to update the commands to the history
shopt -s histappend
PROMPT_COMMAND='history -a'


vi ~/.forward
shantanu.oa+forward@gmail.com

// Change the apache access log setting:
# cat /etc/httpd/conf/httpd.conf | grep LogFormat
#Old Format to be changed to the new format
#LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined
LogFormat "\"%h\" \"%l\" \"%u\" \"%{%Y-%m-%d %H:%M:%S}t\" \"%r\" \"%>s\" \"%b\" \"%{Referer}i\" \"%{User-Agent}i\"" combined


Add the following scripts to /bin/ folder:

# cat /bin/wiki
#!/bin/sh
dig +short txt ${1}.wp.dg.cx


# cat /bin/mylog
#!/bin/sh
mysqlbinlog ${1} | grep -i -e "^update" -e "^insert" -e "^delete" -e "^replace" -e "^alter" | cut -c1-100 | tr '[A-Z]' '[a-z]' | sed -e "s/\t/ /g;s/\`//g;s/(.*$//;s/ set .*$//;s/ as .*$//" | sed -e "s/ where .*$//" | sort | uniq -c | sort -nr

mysqlbinlog ${1} | grep -i ^use | sort -u


# cat /bin/findtable
#!/bin/sh
mysql -e"select TABLE_SCHEMA, TABLE_NAME, ENGINE, TABLE_ROWS, CREATE_TIME FROM information_schema.TABLES where TABLE_NAME LIKE '%$1%';"

# cat /bin/mydisk
#!/bin/sh
mysize=${1:-1000}
find / -type f -size +"$mysize"M -exec ls -lh {} \; | awk '{ print $9 ": " $5 }'

# cat /bin/mydiff
#!/bin/sh

for i in {1..10}
do
mysql -e"SELECT STRAIGHT_JOIN
LOWER(gs0.VARIABLE_NAME) AS variable_name,
gs0.VARIABLE_VALUE AS variable_value_0,
gs1.VARIABLE_VALUE AS variable_value_1,
(gs1.VARIABLE_VALUE - gs0.VARIABLE_VALUE) AS variable_value_diff,
(gs1.VARIABLE_VALUE - gs0.VARIABLE_VALUE) / 10 AS variable_value_psec,
(gs1.VARIABLE_VALUE - gs0.VARIABLE_VALUE) * 60 / 10 AS
variable_value_pminute
FROM
(
SELECT
VARIABLE_NAME,
VARIABLE_VALUE
FROM
INFORMATION_SCHEMA.GLOBAL_STATUS
UNION ALL
SELECT
'',
SLEEP(30)
FROM DUAL
) AS gs0
JOIN INFORMATION_SCHEMA.GLOBAL_STATUS gs1 USING (VARIABLE_NAME)
WHERE
gs1.VARIABLE_VALUE != gs0.VARIABLE_VALUE
;"

done



# cat /bin/mycheck
#!/bin/sh
master=$(mysql -e"show slave status\G" | grep "Master_Host" | awk -F":" '{print $2}')
second_master=$(mysqladmin processlist | grep 'Binlog' | awk -F"|" '{print $4}' | awk -F":" '{print $1}')
remote_server=${1:-$master}
remote_server=${remote_server:-$second_master}

user_name=${2:-root}
user_password=${3:-root@123}

echo "Comparing localhost with remote server at $remote_server using $user_name and $user_password"

echo `date`
for dbName in `mysqlshow`
do
/usr/bin/mk-table-checksum h=localhost,P=3306 --databases $dbName h=${remote_server},u=$user_name,p=$user_password,P=3306 --databases $dbName --count --no-crc | /usr/bin/mk-checksum-filter
done


// add MAILTO=shantanu.oa@gmail.com to crontab

// Check if tuning-primer.sh is installed

// make sure maatkit is installed

// install adminer.php to manage the mysql database
wget -directory-prefix=/var/www/html/ -O adminer.php http://downloads.sourceforge.net/project/adminer/Adminer/Adminer%202.0.0/adminer-2.0.0-en.php

_____

cat /bin/multi
#!/bin/sh
# chmod 755 /bin/multi
# to start or stop multiple instances of mysql
# multi start
# multi stop
# change the root user and password # default action is to start

action=${1:-"start"}

stop()
(
for socket in {2..9}
do
mysqladmin shutdown -uroot -proot@123 --socket=/tmp/mysql.sock$socket
done
)

start()
(
for socket in {2..9}
do
mysqld_multi start $socket
done
)

$action

_____

Here are a few important crons :

# Check differences, use the table-sync utility to check the differences
# /usr/bin/mk-table-sync --print
55 22 * * * (/usr/bin/mk-table-checksum h=10.10.10.10,u=root,p=root@123,P=3306 --databases test h=11.11.11.11,u=root,p=root@123,P=3306 --databases test | /usr/bin/mk-checksum-filter) | sed "s/^/$(date '+\%Y\%m\%d\%H\%M') /g" >> /home/shantanu/mk_check_sed.txt 2>> /home/shantanu/mk_check_sed_err.txt

# 54 23 * * * diff <(mysqldump -h11.11.11.11 -uroot -proot@123 test myinfo --skip-extended-insert) <(mysqldump -h10.10.10.10 -uroot -proot@123 test myinfo --skip-extended-insert) --side-by-side --suppress-common-lines --width=690 | more

52 06 * * * grep nagios /var/log/messages | grep "`date '+\%b \%e'`" | mail -s"nagios log of `hostname`" monitor+`hostname`@wavecrest.gi > /home/shantanu/nagios_success.txt 2> /home/shantanu/nagios_err.txt

## log alerts to /var/log/messages
# mysql high processes
*/5 * * * * myvar1=$(mysqladmin -h11.11.11.11 -uroot -proot@123 processlist | wc -l | awk '{print int($1)}'); [ $myvar1 -gt 80 ] && logger "MySQL processes on 101 are high $myvar1 at $(date)" >/dev/null 2>&1
*/5 * * * * myvar1=$(mysqladmin -h10.10.10.10 -uroot -proot@123 processlist | wc -l | awk '{print int($1)}'); [ $myvar1 -gt 80 ] && logger "MySQL processes on 102 are high $myvar1 at $(date)" >/dev/null 2>&1


# kill query running too long
#* * * * * /usr/bin/mk-kill --print --daemonize --interval 5 --busy-time 2000 --ignore-info '(?i-smx:^insert|^update|^delete)' --match-info '(?i-xsm:select)' --log /var/log/mk-kill.log --execute-command '(echo "Subject: mk-kill query found on `hostname`"; tail -1 /var/log/mk-kill.log) | mail -s "mk-kill on `hostname`" monitor+`wavecrest`@wavecrest.gi' --kill-query >> /home/shantanu/kill_success.txt 2>> /home/shantanu/kill_err.txt
_____

ps helper

A new database ps_helper is created and useful functions like format_bytes, format_time are installed along with diasnostic table views based on performance_schema.

curl http://www.markleith.co.uk/wp-content/uploads/2012/07/ps_helper_55.sql_.txt | mysql

This is 5.5 version. Change the filename to 56.sql in order to install on 5.6 version.

_____

// remove myisam tables from a schema UpORS

mysql information_schema -Bse"select concat('drop table ', TABLE_NAME, ';') from TABLES WHERE TABLE_SCHEMA = 'UpORS' and ENGINE = 'MyISAM'" | mysql UpORS


// remove innodb tables without any foreign key refernce from schema UpORS

mysql information_schema -Bse"select concat('drop table ', a.TABLE_NAME, ';') from TABLES AS a left join
(select TABLE_NAME from TABLE_CONSTRAINTS   where CONSTRAINT_SCHEMA = 'UpORS' GROUP BY TABLE_NAME) as b
on a.TABLE_NAME = b.TABLE_NAME
WHERE a.TABLE_SCHEMA = 'UpORS' and   b.TABLE_NAME IS NULL" | mysql UpORS
 

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October 09, 2009

 

Naming my baby

Append the variable name with the variable type. for e.g. instead of just saying FirstName you can call it strFirstName like this...

$strFirstName = ’sonny’;
$intAge = 5;

There are 2 types of Case styles:

Pascal Case -> ThisIsPascalCase (Also Called Upper Camel Case)

Camel Case -> thisIsCamelCase (Also Called Lower Camel Case)

_____

Zend Framework has defined the following guidelines for naming variables and function names.

Classes – PascalCase (UpperCamelCase)
Class names must match the name of the directory on the file system that contains the class file. If you have a class file named Car.php in the path ‘/Models/Car.php’ then the class name would have to be Models_Car.

Functions and Methods – camelCase
Names must describe behavior of function or method.
Methods that are declared with private or protected visibility modifier must start with an _.

Constants – ALL_CAPS

Labels:


 

Pear Problem

Some PEAR installations on PHP 5.2.9 and 5.2.10 seem to be corrupted. When trying to install something, you will get the error:

pear.php.net is using a unsupported protocal – This should never happen. install failed

This problem comes from corrupted channel files. Go into your PEAR php directory and backup .channels directory:

cd `pear config-get php_dir`
mv .channels .channels-broken
pear update-channels

This means you lost all your channels except for the default ones (pear, pecl, doc and __uri) – but at least you do not have to re-install PEAR.

Labels:


 

PHP memory management

Do not forget to delete the data stored in the buffer.

$long_result = mysql_query('SELECT * FROM `posts`');
//Output $long_result
unset($long_result);
$var = 'Lorem ipsum dolor sit amet. Lorem ipsum dolor sit.';
echo $var;
unset($var);
?>

Labels:


 

php.ini file setting

There are many people who talk about my.cnf setting for mysql. But I do hardly hear anything about php.ini setting. Here are a few tips...

asp_tags = Off
display_errors = On
display_startup_errors = Off
log_errors = Off
safe_mode = Off
register_globals = Off
short_open_tag = Off
sql.safe_mode = Off
max_input_time = 60
magic_quotes_gpc = Off
track_errors = Off

Labels:


 

Show create trigger

MySQL 5.0 lacks "SHOW CREATE TRIGGER". Here's a VIEW to list all triggers and (a close approximation of) their CREATE statements.

CREATE VIEW `SHOW_CREATE_TRIGGERS` AS
SELECT
TRIGGER_NAME AS 'trigger_name'
,CONCAT_WS(
" ",
"DELIMITER $$\nCREATE TRIGGER",
TRIGGER_NAME,
ACTION_TIMING,
EVENT_MANIPULATION,
"ON",
EVENT_OBJECT_TABLE,
"FOR EACH ROW",
ACTION_STATEMENT,
"$$\nDELIMITER ;"
) AS 'sql'
FROM information_schema.triggers;

Labels:


October 08, 2009

 

Pager to compare resultset

While optimizing a query, one might need to know if the query will return the exact same results as the last query. We can use the combination of pager and md5 checksum for the purpose.

mysql> pager md5sum

mysql> select * from City as c, Country ct where c.countrycode = ct.code;
3c8c6b8331c9270f8565edd1a8b8d7a5 -
4079 rows in set (0.05 sec)

mysql> select * from City c join Country ct ON(c.countrycode = ct.code);
3c8c6b8331c9270f8565edd1a8b8d7a5 -
4079 rows in set (0.05 sec)

mysql> nopager

Or just log out and log back in.

Labels:


 

Mysql prompt and tee

You can change the MySQL prompt as well as start saving the output to a text file.
mysql -uroot -p --prompt="(\r:\m)\_mysql>" --show-warnings --tee="/home/sqltee.txt"

You can also create an alias and add the command to the .bashrc file that can be found in the home directory.

vi ~/.bashrc
alias mysql_new='mysql -uroot -p --prompt="(\r:\m)\_mysql>" --show-warnings --tee="/home/sqltee.txt"'

Labels:


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