Backup function code analysis

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Backup Code Analysis

• The key file where the backup originates is admin/db/maintenance_db.inc

• In it, the key function that starts the backup is function db_backup()

  • Parameter $tbpref makes it generic enabling usage of other prefixes possibly within extensions or in customisations

  • Creates the name of the backup sql file and goes to function db_export()

• The actual backing up is done in the function db_export()

  • Parameter $tbpref makes it generic enabling usage of other prefixes possibly within extensions or in customisations

  • If no prefix is there for a company and other companies data resides in the same db, then all tables in the db including those of other companies in it too will get backed up!

  • Sets max chunk size before writing to sql backup file to 2MB or if present, from memory_limit value in php.ini

  • Writes standard parameters to sql backup as comments

  • Writes user comments to sql backup as comments

  • Acquire all table names in db and shortlist them based on prefix or all on no prefix!

  • SQL comment character hardcoded as "#" throughout

If your backup is taking too long, then tune the MySQL server with mysqltuner. In debian, install with apt-get install mysqltuner. Usage:

mysqlcheck -o mydbname
mysqltuner

and monitor with:

tail -fn0 /var/log/mysql.err
tail -n15 /var/log/mysql.err
vmstat 5 5