Linux, programming and more
Following line will query all mysql user with their grants and print the creation statements for them.
By copy pasting or by filling a SQL-file, you can easily migrate all MySQL-user to a new mysql or mariaDB instance.
mysql -u root -p"YOUR_PW" -Ne "select distinct concat( \"SHOW GRANTS FOR '\",user,\"'@'\",host,\"';\" ) from mysql.user;" mysql | \
mysql -u root -p"YOUR_PW"| \
sed 's/\(GRANT .*\)/\1;/;s/^\(Grants for .*\)/## \1 ##/;/##/{x;p;x;}'
MySQL-Replication could be a kind of load balancing for querieng applications or active failover/backup node which has the same data.
Also for common heavy loaded scenarios, where the primary write-queries are going to the master node and all read-queries are running against the slave node.
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SQLite is good for testing and simple single-user Nextcloud instance,
but it does not scale for multiple-user production cases. For the first Installation its quiet simple and reliable.
After some years of usage my SQLite-database reached a size of 130MB and the performance was not more the same as after the first days.
You can convert a SQLite database to a more performing MariaDB database with the Nextcloud command line tool:
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In some cases databases gets corrupted(shit happens). After a hardware fail or not correct usage like a “kill -9” of mysqld process without gracefully flushing of opened tables.
After the start of mysqld.service, you can get a log-entry in your mysqld-log file, which informs you about the corruption of database, like this one “corruption in the InnoDB tablespace“.
In some cases mysqld.service will crash every n-minutes..
Independently of the symptoms the crashed database should be repaired immediately!
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Collection of some MySQL commands, very useful to create and restore MySQL-Backups.
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