Shantanu's Blog

Database Consultant

December 21, 2010

 

MySQL Case Study - 181

ON DUPLICATE KEY insert into an audit or log table

Is there a way to accomplish this?

INSERT IGNORE INTO some_table (one,two,three) VALUES(1,2,3)
ON DUPLICATE KEY (INSERT INTO audit_table VALUES(NOW(),'Duplicate key ignored')

I really don't want to use PHP for this :(

http://stackoverflow.com/questions/3884344/mysql-on-duplicate-key-insert-into-an-audit-or-log-table
_____

If you want to consider using a stored procedure, you can use a DECLARE CONTINUE HANDLER. Here's an example:

CREATE TABLE users (
username VARCHAR(30),
first_name VARCHAR(30),
last_name VARCHAR(30),
PRIMARY KEY (username)
);

CREATE TABLE audit_table (timestamp datetime, description varchar(255));

DELIMITER $$
CREATE PROCEDURE add_user
(in_username VARCHAR(30),
in_first_name VARCHAR(30),
in_last_name VARCHAR(30))
MODIFIES SQL DATA
BEGIN
DECLARE duplicate_key INT DEFAULT 0;
BEGIN
DECLARE EXIT HANDLER FOR 1062 SET duplicate_key = 1;

INSERT INTO users (username, first_name, last_name)
VALUES (in_username, in_first_name, in_last_name);
END;

IF duplicate_key = 1 THEN
INSERT INTO audit_table VALUES(NOW(), 'Duplicate key ignored');
END IF;
END$$
DELIMITER ;

Let's add some data, trying to insert a duplicate key:

CALL add_user('userA', 'Bob', 'Smith');
CALL add_user('userB', 'Paul', 'Green');
CALL add_user('userA', 'Jack', 'Brown');

Result:

SELECT * FROM users;
+----------+------------+-----------+
| username | first_name | last_name |
+----------+------------+-----------+
| userA | Bob | Smith |
| userB | Paul | Green |
+----------+------------+-----------+
2 rows in set (0.00 sec)

SELECT * FROM audit_table;
+---------------------+-----------------------+
| timestamp | description |
+---------------------+-----------------------+
| 2010-10-07 20:17:35 | Duplicate key ignored |
+---------------------+-----------------------+
1 row in set (0.00 sec)

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December 15, 2010

 

Replication: step-by-step

ssh to master and slave in 2 different windows. Make sure maatkit is installed on both servers. start the script logging and mysql logging.

Master: 10.10.10.56
Slave: 10.10.10.3

$$ On 10.10.10.3 (Slave)
// check disk space
// make sure innodb is configured but all logs are disabled in my.cnf
// create a super user equivalent to root
# mysql -e"grant all on *.* to 'shantanu'@'%' identified by 'shantanu@123' with grant option;"
# mysql -e"grant all on *.* to 'shantanu'@'localhost' identified by 'shantanu@123' with grant option;"

// open the port for copying the dump file from master
# time nc -l 1234 > toall_master_data.sql

$$ On 10.10.10.56 (Master)
// create a super user equivalent to root
# mysql -e"grant all on *.* to 'shantanu'@'%' identified by 'shantanu@123' with grant option;"
# mysql -e"grant all on *.* to 'shantanu'@'localhost' identified by 'shantanu@123' with grant option;"

// copy the users and privileges to slave
# mk-show-grants -ushantanu -pshantanu@123 | mysql -h10.10.10.3 -ushantanu -pshantanu@123

// take the dump
# time mysqldump --all-databases -R --single-transaction --master-data=2 | perl /home/shantanu/dumper.pl --delete > to_all_db_to_3.sql
real 3m21.331s
user 1m10.234s
sys 0m10.378s

// send the dump file to slave
# time nc 10.10.10.3 1234 < to_all_db_to_3.sql
real 1m17.768s
user 0m1.800s
sys 0m12.713s

$$ On 10.10.10.3 (Slave)
# time mysql < to_all_db_to_3.sql

~ 40 minutes

// run the chnage master to command generated from the following file
# head -100 toall_master_data.sql | grep 'CHANGE MASTER TO' | sed 's/--//' | replace ";" " , MASTER_USER='slave_user', MASTER_PASSWORD='slave_user', MASTER_HOST='10.10.10.56';"

// check slave status
mysql -e"show slave status\G"

// compare row count in test database with master
mk-table-checksum h=localhost,u=shantanu,p=shantanu@123,P=3306 --databases test h=10.10.10.56,u=shantanu,p=shantanu@123,P=3306 --databases test | mk-checksum-filter

// drop user shantanu
mysql -ushantanu -pshantanu@123 -e"drop user shantanu;"

$$ On 10.10.10.56 (Master)
// compare row count in test database with slave
mk-table-checksum h=localhost,u=shantanu,p=shantanu@123,P=3306 --databases test h=10.10.10.3,u=shantanu,p=shantanu@123,P=3306 --databases test | mk-checksum-filter

// drop user shantanu
mysql -ushantanu -pshantanu@123 -e"drop user shantanu;"

Or run the shell script to check if all the tables are in sync

# time sh -xv slave_check.sh

# vi slave_check.sh
#/bin/sh
# change the slave IP as default IP address if no IP is provided
myslave=${1:-10.10.10.3}
for dbName in `mysqlshow`
do
mk-table-checksum h=localhost,u=shantanu,p=shantanu@123,P=3306 --databases $dbName h=$myslave,u=shantanu,p=shantanu@123,P=3306 --databases $dbName --no-crc --count | mk-checksum-filter
done

This can also do done in a single command as shown below:

for dbName in `mysqlshow -uroot -proot@123`; do /usr/bin/mk-table-checksum h=localhost,u=root,p=root@123,P=3306 --databases $dbName h=10.10.10.11,u=root,p=root@123,P=3306 --databases $dbName --count --no-crc | /usr/bin/mk-checksum-filter; done

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