I did some drawing exercise and put XtraDB / InnoDB internals in Visio diagram: The XtraDB differences and main parameters are marked out. PDF version is there http://www.percona.com/docs/wiki/percona-xtradb:internals:start.
InnoDB uses its own mutexes and read-write locks instead of POSIX-mutexes pthread_mutex*, the main reason for that is performance, but InnoDB’s implementation isn’t ideal and on modern SMP boxes can cause serious performance problems. Let’s look on InnoDB mutex (schematic for simplification):
Have you wanted to compress only certain types of columns in a table while leaving other columns uncompressed? While working on a customer case this week I saw an interesting problem where a table had many heavily utilized TEXT fields with some read queries exceeding 500MB (!!), and stored in a 100GB table. In this […]
This is probably the feature I missed most from early days when I started to use InnoDB instead of MyISAM. Since that I figured out how to survive without it, but this is first question I hear from customers who migrated from MyISAM to InnoDB – can I just copy .ibd files from one server […]
One of InnoDB’s features is that memory allocated for internal tables definitions is not limited and may grow indefinitely. You may not notice it if you have an usual application with say 100-1000 tables. But for hosting providers and for user oriented applications ( each user has dedicated database / table) it is disaster. For […]
When running InnoDB you are able to dig into the engine internals, look at various gauges and counters, see past deadlocks and the list of all open transactions. This is in your reach with one simple command —
SHOW ENGINE InnoDB STATUS
. On most occasions it works beautifully. The problems appear when you have a large spike in […]
In one of his recent posts Vadim already gave some information about possible benefits from using new InnoDB file format but in this post I’d like to share some real-life example how compression in InnoDB plugin could be useful for large warehousing tasks.
There was several changes in InnoDB to fix scalabilty problems, so I ran benchmark to check new results and also compare overall performance of InnoDB in 5.0 and 5.1 before and after fixes. Problems in InnoDB that were fixed: Thread trashing issues with count of theads 100+. In this case performance of InnoDB degraded dramatically. […]
I actually don’t remember exactly whether it was in 2006, 2007 or 2008 — but around that time the MySQL community had one of the greatest MySQL conferences put on by O’Reilly and MySQL. It was a good, stable, predictable time. Shortly thereafter, the MySQL world saw acquisitions, forks, times of uncertainly, more acquisitions, more forks, […]
As an instructor with Percona I’m sometimes asked about the differences between the READ COMMITTED and REPEATABLE READ transaction isolation levels. There are a few differences between READ-COMMITTED and REPEATABLE-READ, and they are all related to locking.