Check all tables on MySQL

Data corruption is every DBA’s worst nightmare and can happen anytime. Use this command to check and repair all tables on a MySQL database :

mysqlcheck -u root -p --auto-repair --check --optimize --all-databases

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Rename a Postgresql database

#database #postgresql

Here's the procedure to rename a PostgreSQL database: 1. Disconnect from the database that you want to rename and connect to a different database. 2. Check and terminate all active connections to the database that you want to rename. 3. Use the `ALTER DATABASE` statement to rename the database to the new one. Let’s take a look at an example of... Read more

20 May 2019 - 1 minute read

How to duplicate a Postgresql database

#database #postgresql

If you need to duplicate an existing Postgresql database, and possibly transfer ownership of the database objects to a new user, here's how to do that in a quick way: ```sql -- First, I recommand getting the size of the database to copy, as this might be important for the rest of the process. SELECT pg_database.datname,pg_size_pretty(pg_databas... Read more

20 Apr 2019 - less than 1 minute read

Forcing ASMM component to shrink

#oracle #database

Here's the way to force the shared pool to shrink dynamically. Documentation states that ASMM can only increase shared pool, and can't shrink. When the automatic shared memory management feature is enabled, the internal tuning algorithm tries to determine an optimal size for the shared pool based on the workload. It usually converges on this va... Read more

20 Mar 2019 - 2 minute read

Last rowcount in MySQL

#mysql

Suppose you want to count the number of lines returned by the last SQL statement issued. For **select** statements you can use the *FOUND_ROWS* construct: ```sql SELECT SQL_CALC_FOUND_ROWS something FROM your_table WHERE whatever; SELECT FOUND_ROWS(); ``` This will return the number of rows in the last **select** query (or if the first query ... Read more

20 Sep 2016 - less than 1 minute read

MySQL punch user creation DDL

#mysql

You can get the DDL necessary to duplicate an existing user with the following system command: ``` MYSQL_CONN="-uroot -ppassword" mysql ${MYSQL_CONN} --skip-column-names -A -e "SELECT CONCAT('SHOW GRANTS FOR ''',user,'''@''',host,''';') FROM mysql.user WHERE user'' " | mysql ${MYSQL_CONN} --skip-column-names -A | sed 's/$/;/g' > MySQLUserGrants... Read more

20 Jul 2016 - less than 1 minute read

InnoDB table rebuild

#mysql

### PROBLEM On a **MySQL 5.6** database server, the *ibdata1* file includes 5 InnoDB tables in the mysql schema. ```sql mysql> select table_name from information_schema.tables -> where table_schema='mysql' and engine='InnoDB'; +----------------------+ | table_name | +----------------------+ | innodb_index_stats | | innodb_table... Read more

20 Jun 2016 - 1 minute read