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Is there a MySql binary dump format? Or anything better than plain text INSERT statements?

Posted by: admin November 30, 2017 Leave a comment

Questions:

Is there anything better (faster or smaller) than pages of plain text CREATE TABLE and INSERT statements for dumping MySql databases? It seems awfully inefficient for large amounts of data.

I realise that the underlying database files can be copied, but I assume they will only work in the same version of MySql that they come from.

Is there a tool I don’t know about, or a reason for this lack?

Answers:

Not sure if this is what you’re after, but I usually pipe the output of mysqldump directly to gzip or bzip2 (etc). It tends to be a considerably faster than dumping to stdout or something like that, and the output files are much smaller thanks to the compression.

mysqldump --all-databases (other options) | gzip > mysql_dump-2010-09-23.sql.gz

It’s also possible to dump to XML with the --xml option if you’re looking for “portability” at the expense of consuming (much) more disk space than the gzipped SQL…

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Answers:

Sorry, no binary dump for MySQL. However the binary logs of MySQL are specifically for backup and database replication purposes http://dev.mysql.com/doc/refman/5.5/en/binary-log.html . They are not hard to configure. Only changes such as update and delete are logged, so each log file (created authomatically by MySQL) is also an incremental backup of the changes in the DB. This way you can save from time to time a whole snapshot of the db (once in a month?), and then store just the log files, and in case of crash, restore the latest snapshot and run through the logs.

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It’s worth noting that MySQL has a special syntax for doing bulk inserts. From the manual:

INSERT INTO tbl_name (a,b,c) VALUES(1,2,3),(4,5,6),(7,8,9);

Would insert 3 rows in a single operation. So loading this way isn’t as inefficient as it might otherwise be with one statement per row, and instead of 129 bytes in 3 INSERT statements, this is 59 bytes, and that advantage only gets bigger the more rows you have.

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I’ve never tried this, but aren’t mysql tables just binary files on the hard drive? Couldn’t you just copy the table files themselves? Presumably that’s essentially what you are asking for.

I don’t know how to stitch that together, but it seems to me a copy of /var/lib/mysql would do the trick