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Displaying posts with tag: mysqldump (reset)

Upgrading to Barracuda & getting rid of huge ibdata1 file
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Some of this is old stuff, but more people are now converting to InnoDB plugin, so as to enjoy table compression, performance boosts. Same holds for people converting to Percona’s XtraDB. InnoDB plugin requires innodb_file_per_table. No more shared tablespace file.

So your ibdata1 file is some 150GB, and it won’t reduce. Really, it won’t reduce. You set innodb_file_per_table=1, do ALTER TABLE t ENGINE=InnoDB (optionally ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=8), and you get all your tables in file-per-table …

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Excluding databases from mysqldump
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A question that came up during the MySQL track at the UKOUG conference in Birmingham was "Can I exclude only a few databases from mysqldump? Let's say that I have 50 databases, and I want to dump all of them, except a few."
As many know, mysqldump has an option to ignore specific tables. SO if you have 1,000 tables in a databases, you can tell mysqldump to dump all the tables except a few ones.
There is no corresponding option to exclude one or more databases.
However, if you know your command line tools, the solution is easy:
First, we get the list of all databases:

mysql -B -N -e 'show databases' …





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Why mysqldump is converting my tables from InnoDB to MyISAM?
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First of all: mysqldump is not converting tables. It is something else. Here is the story:

One of my clients had a case when they were migrating to a new mysql server: they used mysqldump to export data from the old server (all InnoDB) and imported it to the new server. When finished, all the tables became MyISAM on the new server. So they asked me this question:
“Why mysqldump is converting my tables from InnoDB to MyISAM?”

First of all we made sure that the tables are InnoDB on the old server. It was true.
Second we run “show engines” on the new server:





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An argument for using mysqldump
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I fully agree with Morgan’s An argument for not using mysqldump. This post does not come to contradict it, but rather shed a positive light on mysqldump.

I usually prefer an LVM snapshot based backup, or using XtraBackup. And, with databases as large as dozens of GB and above, I consider mysqldump to be a poor alternative. Poor in runtime, poor in overhead while taking the backup.

However once in a while I get to be reminded that mysqldump just works.

As a recent example, I had a …

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An argument for not using mysqldump
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I have a 5G mysqldump which takes 30 minutes to restore from backup.  That means that when the database reaches 50G, it should take 30x10=5 hours to restore.  Right?  Wrong.

Mysqldump recovery time is not linear.  Bigger tables, or tables with more indexes will always take more time to restore.

If I restore from a raw backup (LVM snapshot, xtrabackup, innodb hot backup), it is very easy to model how much longer recovery time will take:

Backup is 80G
Copy is at 70MB/s.
10G is already complete.
= ((80-10) * 1024)/70/60 = ~17 minutes …


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Setting up slave, stripping indexes and changing engines, on the fly
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Warning, the following is quite ugly, but does the job :)

A while back I needed to create an archive slave database from a half a terabyte myisam master and had space restrictions. I could not dump the db, load it, then drop keys (archive doesn’t support keys apart from a primary key on one column as of 5.1), alter engine etc (would take even longer than it took either way). So an ugly single liner came to mind and worked nicely too.

mysqldump -uuser -ppassword -h127.0.0.1 -P3306 dbname --master-data=1 | sed 's/ENGINE=MyISAM/ENGINE=archive/g' | grep -v '^ UNIQUE KEY' | grep -v '^ KEY' | perl …

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Easy MySQL: how to backup databases to a remote machine
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Here’s a simple answer to a simple question. “How do I run a backup of MySQL to another machine without writing to the local server’s filesystem?” – this is especially useful if you are running out of space on the local server and cannot write a temporary file to the filesystem during backups.

Method one – this writes a remote file.
mysqldump [options] [db_name|--all-databases]| gzip -c | ssh user@host.com "cat > /path/to/new/file.sql.gz"

Method two – this writes directly into a remote mysql server
mysqldump [options] [db_name|--all-databases]| mysql --host=[remote host] –user=root –password=[pass] [db_name]

mysqldump each object separately
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As a continuation to a previous blog post last week and inspired by Kedar I have created a small script to export tables, stored procedures, functions and views into their respective file. It works for multiple databases where you can specify a list of databases too and although things like events, triggers and such are still missing they are easily added.

It is especially …

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Dumping DDL – mysqldump tables, stored procedures, events, triggers (separately)
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If you like to keep your ddl backed up in some source management tool like svn or cvs and want to do it individually for stored procedures, events, triggers, tables and such rather than having a single file you can easily do so using the below. You could even include the –skip-dump-date or –skip-comments and use the below to compare ddl daily checking for alterations thus making sure you are aware of any ddl changes done on the database.

user=backup_user
password=`cat ~/.backup_password`
hostname=127.0.0.1
port=3306
dbname=test_db
path=/home/mysql/ddl






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Simple Backup Server
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I have not written an article in a while, I partially blame it on the World Cup and my day job. The time has come to share some of my recent experiences with a neat project to provide several teams internally with current MySQL backups.

When faced with these types of challenges is my first step is to look into OSS packages and how can they be combined into an actual solution. It helps me understand the underlying technologies and challenges.

ZRM BackupI have reviewed Zmanda's Recovery Manager for MySQL Community Edition in the Fall 2008 issue of …



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10 Newer Entries Showing entries 31 to 40 of 62 10 Older Entries

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