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daily_issues [2011/04/14 01:44] – k2pateldaily_issues [2020/08/10 02:35] (current) – external edit 127.0.0.1
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 </code> </code>
  
 +===== Mysql Generate hash for password =====
 +<code mysql>
 +SELECT PASSWORD('mypass');
 +</code>
  
 +OR
 +
 +<code mysql>
 +SELECT OLD_PASSWORD('mypass');
 +</code>
  
 ==== MySQL Cluster information gathering ==== ==== MySQL Cluster information gathering ====
Line 78: Line 87:
 Following method shows how to enable it in table without restarting,\\ Following method shows how to enable it in table without restarting,\\
 Also same you can apply in my.cnf\\ Also same you can apply in my.cnf\\
 +
 +Structure usually created with mysql installation if you don't see could be old structure.\\
 +try running //mysql_upgrade//
  
 <code sql | Table Structure> <code sql | Table Structure>
Line 95: Line 107:
 log_output=TABLE,FILE log_output=TABLE,FILE
 </code> </code>
 +
 +Following command can help you apply changes without restart.
  
 <code sql | Command > <code sql | Command >
 SET GLOBAL log_output='TABLE'; SET GLOBAL log_output='TABLE';
 SET GLOBAL general_log='ON'; SET GLOBAL general_log='ON';
 +</code>
 +
 +How to flush log.
 +
 +<code sql | Flush log>
 +mysql -u root -pp4ssw0rd -e "TRUNCATE TABLE mysql.general_log"
 +</code>
 +
 +==== mysql dump only partition information ====
 +If you were planning to drop a partition, you may need to back it up. find out the range of the partition by
 +
 +<code>
 +show create table tablename
 +</code>
 +
 +replace the range fields as follows:
 +<code>
 +mysqldump -S --no-create-info --where="RANGE(day) >= lowrange AND RANGE(day) < highrange" database_name table_name > /jtmp/table.sql
 +</code>
 +
 +==== Reading Binlog ====
 +
 +Simple command to read binlog is
 +<code bash>
 +mysqlbinlog mysql-bin.000013
 +</code>
 +
 +You can use following regularly used options.
 +<code bash>
 +--start-datetime=
 +--start-position=
 +--server-id=
 +</code>
 +
 +==== Can't open file ====
 +
 +I've started seeing following error in my log.\\
 +
 +<code text>
 +[ERROR] /usr/libexec/mysqld: Can't open file: 
 +</code>
 +
 +It is caused by file discriptor limit set by the system.\\
 +You can check that by changing your shell to mysql user and running following command.
 +
 +<code bash>
 +ulimit -a
 +</code>
 +
 +In order to increase the open file limit.\\
 +edit following file.\\
 +
 +<code bash /etc/security/limits.conf>
 +mysql  soft  nofile  49152
 +mysql  hard  nofile  65536
 +</code>
 +
 +Now you can check mysql for limit seen by mysql.\\
 +login to mysql as root and run following command.\\
 +
 +<code mysql>
 +show GLOBAL VARIABLES LIKE "open%";
 +</code>
 +
 +Now you can modify it to increased limit in limits.conf.\\
 +by editing following file.
 +
 +<code bash /etc/my.cnf>
 +[mysqld]
 +open-files-limit=49152
 +
 +[mysqld_safe]
 +open-files-limit=49152
 +</code>
 +
 +restart mysql and check again it should represent new value.
 +
 +==== InnoDB: Unable to lock ./ibdata1, error: 11 ====
 +
 +I've stumble across this issue while running mariadb server in VM Guest.\\
 +I believe this happens sometime when VDP is doing backup or machine is being migrated by DRS.
 +
 +In my case, i've enable innodb per tables. So i've to clear lock from all files in subfolder.\\
 +In order to fix the issue, following command usually fix the issue.
 +<code bash>
 +systemctl stop mariadb
 +cd /var/lib/mysql
 +for i in `find . -name '*.ibd'`; do mv $i $i.bk; cp -a $i.bk $i ; rm $i.bk ; done
 +systemctl start mariadb
 </code> </code>
daily_issues.1302745442.txt.gz · Last modified: 2020/08/10 02:30 (external edit)