Drupal Databasedump for incremental backups.

Attached is a simple script to backup Drupal databases in an incremental-archive-friendly way (1.7KB). Instead of dumping the database into one big SQL file, this script creates many small files; one per table. With a blacklist option to exclude certain tables. It stores the structure (CREATE TABLE statements) in a separate file too.

Separate files are usefull in an incremental backup situation: Drupal has many tables who's content hardly ever changes, and has tables whos content is completely rewritten every X days (cache, accesslogs, watchdog etc). That way, those rather stale tables will not fill up your backups, while the quick-rotating tables can be excluded alltogether.

This script does not create the incremental backups itself. It merely places them in a directory where your backup-system can pick them up.

Blacklist

Tablenames listed in blacklisted_tables.txt will be ignored, usefull to avoid backups of cached data. blacklisted_tables.txt should be placed in the backup-location. Note: blacklisting watchdog or accesslog may make troubleshooting more difficult: you should probably dump these tables somewhere else: they contain valuable data, but data that you probably don't want to save in backup archives.

Restore

Restoring many fractured files is a bit harder. But 'cat' does its job. If you find yourself restoring a lot, you may want to create a script for it. Or, actually, you may want to fix the cause of those many restores first :) Important is to first run the strcuture into the database, and then the data.

    cat struct_{date}.sql data_*_{date}.sql > mysql ...

On huge backups, you may want to loop trough the dump_data files and import them one a time. On busy environments, close down (or lock) you database first: you really don't want Drupal writing in your database while you are importing. Esp. older Drupals have a habit of fractured inserts, causing broken databases really easy.

Known issues and TODOs

TODO: If you feel uneasy about storing a password in a plaintext file (you should!), have a look at the debian/ubuntu way of passing a system-maintainance cnf file to mysql. Another reason for not wanting passwds used like this, is that they show up, visible for each user on a system, in the ps-table. Feel free to improve this :)

TODO: the tmp_alltables.txt-file is not multithreadsafe. Nor is the simple output dumping. In other words: do not run two instances of this script at once. Something with lockfiles, or unique filenames could be a solution.

DB=database_name
HOST=localhost
USER=database_user
PASS=database_user_password
BACKUP_PATH=/path/to/place/backups

# Run mysqldump to backup the structure (should hardly ever change)
mysqldump --add-drop-table --create-options --no-data --compress -u$USER -p$PASS -h$HOST $DB > $BACKUP_PATH/struct.sql

# Create a list of all tables 
mysql --skip-column-names -u$USER -p$PASS -h$HOST $DB -e'show tables;' > $BACKUP_PATH/tmp_alltables.txt

# Loop trough the list of tables, filter out blackisted and dump each table.
for table in `comm -23 $BACKUP_PATH/tmp_alltables.txt $BACKUP_PATH/blacklisted_tables.txt`; 
do
    mysqldump --no-create-info --complete-insert --compress --force --lock-tables -u$USER -p$PASS -h$HOST $DB $table > $BACKUP_PATH/data_$table.sql;
done

# And clean up
rm $BACKUP_PATH/tmp_alltables.txt

About the author: Bèr Kessels is an experienced webdeveloper with a great passion for technology and Open Source. A golden combination to implement that technology in a good and efficient way. Follow @berkes on Twitter. Or read more about Bèr.

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