Thanks to antville.org

log mysql output

shantanuo — Wed, 19 Feb 2020 10:33:07 GMT

tee output.txtshow global variables;show engine innodb status\Gshow full processlist;show global status;select sleep(60);show engine innodb status\Gshow full processlist;show global status;notee;

change log file size in MySQL

shantanuo — Tue, 11 Feb 2020 10:38:26 GMT

Here are the steps to be followed while changing the log file size in mysql:

SET GLOBAL innodb_fast_shutdwn = 1;
Stop the mysqld server and check the end of the error log file to ensure that the shutdown was clean.
Move the existing log files to another location for extra safety.
Make the size change in the my.cnf and restart.

MySQL common error messages

shantanuo — Tue, 11 Feb 2020 10:13:08 GMT

1146 Table does not exist1054 column does not exist1062 duplicate entry for primary key1406 Data too long for column1064 sql syntax error1111 invalid use of group function1366 incorrect integer value1046 No database selected

compare mysql schema

shantanuo — Sun, 26 Jan 2020 11:49:04 GMT

And here is poor man's schema compare using good old diff command...

mysqldump nasik1 --no-data > nasik1.sql

mysqldump -h1.2.3.4 murtizapur --no-data > murtizapur.sql

diff murtizapur.sql nasik1.sql --side-by-side --suppress-common-lines | grep -v ENGINE | grep -v BTREE > to_study.txt

Or use one of the packages:

code.google.com

www.red-gate.com

www.devart.com

Rank mysql records using variables

shantanuo — Sun, 26 Jan 2020 09:45:19 GMT

SET @rank = 0, @prev_val = NULL;

SELECT rank, correct FROM (SELECT @rank := IF(@prev_val=correct,@rank,@rank+1) AS rank,@prev_val := correct AS correct, uidFROM quiz_user ORDER BY correct DESC)as result WHERE uid=xxxxxxxxxxxx

backup mysql users

shantanuo — Sun, 20 May 2018 13:42:39 GMT

It is easy to backup mysql users -

wget percona.com/get/pt-show-grants;perl pt-show-grants

mysql and shell command

shantanuo — Wed, 16 May 2018 05:47:18 GMT

date -d"-1 day ago" +'%b%d'

equals to

mysql -Bse"select date_format(date(date_add(now() , interval 1 day)),'%b%d')"

Preserving comments in Stored Procedure

shantanuo — Sat, 12 May 2018 10:56:39 GMT

You can write multi line comments in a stored procedure by following mysql to think that it is a version specific code.

/*!9999Multi line comment, retained by mysqlnot executed till it reaches the mysql version 9999 :))*/

percona utility

shantanuo — Wed, 06 Sep 2017 06:22:39 GMT

We can re-create mysql users using the percona utility.

wget percona.com/get/pt-show-grants

chmod 777 pt-show-grants

./pt-show-grants

Backup mysql data using innobackup

shantanuo — Mon, 28 Sep 2015 06:09:42 GMT

BACKUP

innobackupex --user=USERNAME --password=PASSWORD --no-timestamp /data/backups/new_backup <--(PATH OF BACKUP)innobackupex --apply-log /data/backups/new_backup

RESTORE

service mysql stopmkdir /tmp/mysqlmv /var/lib/mysql/* /tmp/mysql/innobackupex --copy-back /data/backups/new_backup <--(PATH OF BACKUP WHERE IS STORED)chown -R mysql: /var/lib/mysqlservice mysql start