Question asked by a student: is there a way to limit a table’s quote on disk? Say, limit a table to 2GB, after which it will refuse to grow? Note that the requirement is that rows are never DELETEd. The table must simply refuse to be updated once it reaches a certain size.
There is no built-in way to limit a table’s quota on disk. First thing to observe is that MySQL has nothing to do with this. It is entirely up to the storage engine to provide with such functionality. The storage engine is the one to handle data storage: how table and keys are stored on disk. Just consider the difference between MyISAM’s .MYD & .MYI to InnoDB’s shared tablespace ibdata1 to InnoDB’s file-per table .ibd files.
The only engine I know of that has a quota is the MEMORY engine: it[Read more...]
MySQL keeps many different files, some contain real data, some contain meta data. Witch ones are important? Witch can your throw away?
This is my attempt to create a quick reference of all the files used by MySQL, whats in them, what can you do if they are missing, what can you do with them.
When I was working for Dell doing Linux support my first words to a customer where “DO YOU HAVE COMPLETE AND VERIFIED BACKUP?” Make one now before you think about doing anything I suggest here.
You should always try to manage your data through a MySQL client. If things have gone very bad this may not be possible. MySQL may not start. If your file system get corrupt you may have missing files. Sometimes people create other files in the MySQL directory (BAD). This should help you understand what is safe to remove.
Before you try to work with one of[Read more...]
I do not know if it is because we're hosting a free webinar on migrating MyISAM to Innodb or some other reason but recently I see a lot of questions about migration from MyISAM to Innodb.
Webinar will cover the process in a lot more details though I would like to go over basics in advance. You can also check my old post on this topic about Moving MyISAM to Innodb as well as searching the blog - We've blogged so much on this topic.
So what are the basics ?
Regression Benchmarks - Make sure to run regression benchmarks in particular in terms of[Read more...]
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:
| Engine | Support | Comment
This week I was one of the presenters at the first Surge Scalability Conference in Baltimore. An event that focused not just on one technology but on what essential tools, technologies and practices system architects need to know about for successfully scaling web applications.
While MySQL is an important product in many environments, it is only one component for a successful technology stack and for many organizations is one of several products that manage your data.
My presentation was on the common MySQL scalability mistakes and how to avoid them. This is a problem/solution approach and is a companion talk with[Read more...]