Shantanu's Blog

Corporate Consultant

August 29, 2011

 

Script to search locked threads

The following script will pick up the thread-id from innodb status page and select the last queries executed by that thread.

#!/bin/sh

mysql -e"show engine innodb status\G" | grep "MySQL thread id " | awk -F"," '{print $1}' | replace 'MySQL thread id' '' | tail | while read -r connectid
do
tail -1000000 /var/log/mysql/general.log | awk '$1 == "'$connectid'" || $3 == "'$connectid'" { print $0 }' | head
tail -1000000 /var/log/mysql/general.log | awk '$1 == "'$connectid'" || $3 == "'$connectid'" { print $0 }' | tail
done

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August 15, 2011

 

Analysing general query log

Here are a few commands to know the schema, IP accessing the data using general log.

time grep -w Connect /var/log/mysql/general.log | awk -F'Connect' '{print $2}' > connectme.log

// connection string
sort connectme.log | uniq -c | sort -n
3350 application_user@10.10.11.26 on db1_16JUL2011
7330 application_user@172.16.55.133 on FWQAdb2
7716 application_user@10.10.11.14 on FWQAdb3
10084 application_user@172.16.155.133 on FWQAdb4

// schema, user and IP count
awk -F' on' '{print $2}' connectme.log | sort | uniq -c | sort -n
4528 db1_29062011
5027 db2_16JUL2011
9295 FWQAdb3
10084 FWQAdb4
10488 FWQAdb5

awk -F'@' '{print $1}' connectme.log | sort | uniq -c | sort -n
46 amar
28450 akbar
31453 anthony
41646 dbagroup

awk -F'@' '{print $2}' connectme.log | awk '{print $1}' | sort | uniq -c | sort -n
4189 10.10.11.167
7157 10.10.11.26
8600 10.10.10.67
9073 10.10.11.14
17414 172.16.155.133

// failed connections analysis
grep 'Access denied' connectme.log | awk -F'@' '{print $1}' | awk '{print $NF}' | sort | uniq -c | sort -n
1 'amar'
1 'akbar'
13 'anthony'
16 'user1'
831 'user2'

grep 'Access denied' connectme.log | awk -F'@' '{print $2}' | awk '{print $1}' | sort | uniq -c | sort -n
6 '10.10.10.69'
26 '10.10.11.140'
815 '10.10.11.57'

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August 12, 2011

 

new data-directory for MySQL

Sometimes you need fresh mysql installation. You need to run script to create default mysql database and system tables. The script is called "mysql_install_db" and is either in the bin or in scripts directory of your mysql installation. Change the my.cnf to reflect new datadir and run mysql_install_db for it to create mysql database and system tables in the new datatir and then start mysqld_safe.

/usr/bin/mysql_install_db --datadir=/mnt/mysql3310

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August 07, 2011

 

Resetting root password

If you have forgotten your root password, you will need to start mysql service with --skip-grant-tables mode and then run the following 2 commands to reset it to root / root@123

UPDATE mysql.user SET Password = password('root@123') WHERE Host = 'localhost' AND User = 'root';

REPLACE INTO mysql.user VALUES ('%','root','*A00C34073A26B40AB4307650BFB9309D6BFA6999', 'Y','Y','Y','Y','Y','Y','Y','Y', 'Y','Y','Y','Y','Y','Y','Y','Y', 'Y','Y','Y','Y','Y','Y','Y','Y', 'Y','Y','Y','Y','Y','','','','', 0,0,0,0,'','');

You may now remove the skip grant tables option and restart mysql service. I assume you are not using old-passwords option in my.cnf that makes it compatible with mysql version 3.0!

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August 06, 2011

 

Changing all users and passwords

Hi,
When the data is made available for development, the DBA needs to change the user privileges to make it more restrictive.
The following statement will create all current users with localhost and % hosts and have the same password for all these users.

mysql -hIP_ADDRESS -uroot -pold_password -P3311 -Bse"
select concat(\"grant all on *.* to '\",User,\"'@'%' identified by 'new_password' with grant option;\") from mysql.user group by user
UNION
select concat(\"grant all on *.* to '\",User,\"'@'localhost' identified by 'new_password' with grant option;\") from mysql.user group by user;" | mysql -h10.10.10.24 -uroot -pold_password -P3311

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August 03, 2011

 

socket file location

There are times when you need to supply the IP address even if you are accessing mysql from localhost. This may happen due to changed socket file.

If I do not change the default location of socket file, I can access mysql from localhost with or without IP
socket=/var/lib/mysql/mysql.sock

But If I change the socket location to some other path in my [mysqld] section then I need to add it to [mysql] and [client] section.

[mysql]
socket=/mysqldata1/mysql/mysql.sock

[client]
socket=/mysqldata1/mysql/mysql.sock

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