Shantanu's Blog

Database Consultant

March 24, 2011

 

Hacking FRM files to switch numeric data types

In order to change any numeric data type to UNSIGNED here is a simple and basic alter table statement that needs to be executed.

alter table frm_hack modify id tinyint unsigned;

But if the table is big, it will take a lot of time and here is a frm hack suggested...

http://www.facebook.com/note.php?note_id=10150115679045933

And here is how it works:

mysql> create table frm_hack(id tinyint, name varchar(100), primary key (id)) engine=InnoDB;
Query OK, 0 rows affected (0.10 sec)

mysql> insert into frm_hack values (1, 'shantanu'), (2, 'john'), (121, 'ram'), (234, 'shyam');
Query OK, 4 rows affected, 1 warning (0.03 sec)
Records: 4 Duplicates: 0 Warnings: 1

mysql> create table frm_hack_new (id tinyint unsigned, name varchar(100), primary key (id)) engine=InnoDB;
Query OK, 0 rows affected (0.08 sec)

mysql> \q
Bye

[root@localhost test]# cp frm_hack_new.frm frm_hack.frm
cp: overwrite `frm_hack.frm'? y

[root@localhost test]# mysql test

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> show create table frm_hack\G
*************************** 1. row ***************************
Table: frm_hack
Create Table: CREATE TABLE `frm_hack` (
`id` tinyint(4) NOT NULL default '0',
`name` varchar(100) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

mysql> show create table frm_hack_new\G
*************************** 1. row ***************************
Table: frm_hack_new
Create Table: CREATE TABLE `frm_hack_new` (
`id` tinyint(3) unsigned NOT NULL default '0',
`name` varchar(100) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

mysql> select * from frm_hack;
+-----+----------+
| id | name |
+-----+----------+
| 1 | shantanu |
| 2 | john |
| 121 | ram |
| 127 | shyam |
+-----+----------+
4 rows in set (0.00 sec)

mysql> flush tables;
Query OK, 0 rows affected (0.00 sec)

mysql> show create table frm_hack\G
*************************** 1. row ***************************
Table: frm_hack
Create Table: CREATE TABLE `frm_hack` (
`id` tinyint(3) unsigned NOT NULL default '0',
`name` varchar(100) default NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

mysql> insert into frm_hack values (213, 'abc');
Query OK, 1 row affected (0.02 sec)

mysql> select * from frm_hack;
+-----+----------+
| id | name |
+-----+----------+
| 213 | abc |
| 1 | shantanu |
| 2 | john |
| 121 | ram |
| 127 | shyam |
+-----+----------+
5 rows in set (0.01 sec)

Labels:


March 20, 2011

 

Finding data / comma in a table record

Here is an easy trick to find the table names where comma "," is being used. I will export the data in "tab" delimited format using maatkit and then look for the comma.

rm -rf /pdump/ && mkdir /pdump/
chmod 777 /pdump/

/usr/bin/mk-parallel-dump --no-gzip --base-dir '/pdump' --databases 'my_db' --tab

# grep -r ',' *.txt | awk -F":" '{print $1}' | sort -u | awk -F"." '{print $1}'
address
address_log

The 2 tables address and address_log in the my_db database has the comma somewhere in its record. This tip can be used to find a word or phrase as well.

Labels:


March 17, 2011

 

Batch processing

Let's assume you want to update the second column of the table to upper case. The following SQL statement will do the needful.
update tbl set second_col = upper(second_col)

But if you want to do it in some other way, or if there are more complex processes involved where an SQL won't work, then here is the solution. This is 4 steps procedure to change the data. An utility called "maatkit" is required for this.

##### create directory and make it writable #####

# cd /home/
# rm -rf /pdump/
# mkdir /pdump
# chmod 777 /pdump/*

##### Download data in TAB or CSV format #####

/usr/bin/mk-parallel-dump -h'localhost' --no-gzip --base-dir '/pdump' --databases 'myDB' --tables 'country' --csv
CHUNK TIME EXIT SKIPPED DATABASE.TABLE
db 0.02 0 0 myDB
all 0.02 0 0 -

##### Change the third column data from one encryption to another #####

sh /home/shantanu/line.sh > /pdump/myDB/temp.txt
mv /pdump/myDB/temp.txt /pdump/myDB/country.000000.txt

##### drop the table insert the updated data back to the table #####

/usr/bin/mk-parallel-restore -h'localhost' --database 'myDB' --tables 'country' '/pdump' --csv
1 tables, 2 files, 1 successes, 0 failures, 0.48 wall-clock time, 0.48 load time

_____

The line.sh shell script looks like this...

#!/bin/sh
# read file line by line
file="/pdump/myDB/country.000000.txt"
while read line
do
# select the second column
mycol=`echo $line | awk -F"," '{print $2}'`

# convert it to upper case
mycol_new=`echo $mycol | tr "[:lower:]" [:upper:]`

# do some more java processing with the value
# replace the upper case text in the text file
echo $line | awk -v var="$mycol_new" -F"," '{print $1 "," var "," $3 "," $4 "," $5 "," $6 "," $7 "," $8}'

done < $file

Labels:


March 09, 2011

 

Mysql Monitor

mysql monitor is the nagios of Database. It is especially useful when you have a bunch of mysql DB servers to manage.

http://www.mysql.com/products/enterprise/monitor.html

Here are 8 steps to enable the monitoring agent on the DB server. It is assumed that the monitor server is already configured and active on a server (for e.g. 10.10.10.63)

1) sudo root
2) download agent
3) Change file permissions
chmod +x mysqlmonitoragent-2.3.1.2044-linux-glibc2.3-x86-64bit-installer.bin

4) Run file
[root@localhost]# ./mysqlmonitoragent-2.3.1.2044-linux-glibc2.3-x86-64bit-installer.bin

5) Start agent
/etc/init.d/mysql-monitor-agent start

6) check status
ps -ef | grep monitor

7) check log
cat /opt/mysql/enterprise/agent/mysql-monitor-agent.log

8) create mysql user for e.g.
mysql> grant all on *.* to 'agent'@'%' identified by 'agent';

_____

The following options must be selected very carefully or else monitor will not work as expected.

Installation directory
Installation directory [/opt/mysql/enterprise/agent]:


How will the agent connect to the database it is monitoring?
[1] TCP/IP
[2] Socket
Please choose an option [1] : 1

----------------------------------------------------------------------------
Components to Install

Monitoring:
Enable the Agent to monitor a MySQL Server [Y/n]: Y

Query Analyzer:
Enable the Aggregator to aggregate Query Analyzer data from an external source [y/N]: N
Enable MySQL Proxy to collect and aggregate Query Analyzer data [y/N]: y

----------------------------------------------------------------------------
Monitored Database Information

MySQL hostname or IP address [127.0.0.1]:

Validate MySQL hostname or IP address [y/N]: N

MySQL Port [3306]:

MySQL Username [agent]: agent

MySQL Password :
Re-enter :
----------------------------------------------------------------------------
Agent User Account Creation

[1] Yes, use the credentials below to create the Agent's user account
[2] No, I've already created the account and I'm sure it's correct
Please choose an option [1] : 2

----------------------------------------------------------------------------
MySQL Enterprise Monitor Options

Hostname or IP address []: 10.10.10.63

Tomcat Server Port [18080]:

Tomcat SSL Port [18443]:

Use SSL? [y/N]: y

Agent Username [agent]: agent

Agent Password :
Re-enter :

Labels:


Archives

June 2001   July 2001   January 2003   May 2003   September 2003   October 2003   December 2003   January 2004   February 2004   March 2004   April 2004   May 2004   June 2004   July 2004   August 2004   September 2004   October 2004   November 2004   December 2004   January 2005   February 2005   March 2005   April 2005   May 2005   June 2005   July 2005   August 2005   September 2005   October 2005   November 2005   December 2005   January 2006   February 2006   March 2006   April 2006   May 2006   June 2006   July 2006   August 2006   September 2006   October 2006   November 2006   December 2006   January 2007   February 2007   March 2007   April 2007   June 2007   July 2007   August 2007   September 2007   October 2007   November 2007   December 2007   January 2008   February 2008   March 2008   April 2008   July 2008   August 2008   September 2008   October 2008   November 2008   December 2008   January 2009   February 2009   March 2009   April 2009   May 2009   June 2009   July 2009   August 2009   September 2009   October 2009   November 2009   December 2009   January 2010   February 2010   March 2010   April 2010   May 2010   June 2010   July 2010   August 2010   September 2010   October 2010   November 2010   December 2010   January 2011   February 2011   March 2011   April 2011   May 2011   June 2011   July 2011   August 2011   September 2011   October 2011   November 2011   December 2011   January 2012   February 2012   March 2012   April 2012   May 2012   June 2012   July 2012   August 2012   October 2012   November 2012   December 2012   January 2013   February 2013   March 2013   April 2013   May 2013   June 2013   July 2013   September 2013   October 2013   January 2014   March 2014   April 2014   May 2014   July 2014   August 2014   September 2014   October 2014   November 2014   December 2014   January 2015   February 2015   March 2015   April 2015   May 2015   June 2015   July 2015   August 2015   September 2015   January 2016   February 2016   March 2016   April 2016   May 2016   June 2016   July 2016   August 2016   September 2016   October 2016   November 2016   December 2016   January 2017   February 2017   April 2017   May 2017   June 2017   July 2017   August 2017   September 2017   October 2017   November 2017   December 2017   February 2018   March 2018   April 2018   May 2018   June 2018   July 2018   August 2018   September 2018   October 2018   November 2018   December 2018   January 2019   February 2019   March 2019   April 2019   May 2019   July 2019   August 2019   September 2019   October 2019   November 2019   December 2019   January 2020   February 2020   March 2020   April 2020   May 2020   July 2020   August 2020   September 2020   October 2020   December 2020   January 2021   April 2021   May 2021   July 2021   September 2021   March 2022   October 2022   November 2022   March 2023   April 2023   July 2023   September 2023   October 2023   November 2023  

This page is powered by Blogger. Isn't yours?