Relationship of database (MySql) to an engine (InnoDB)?

Question

There's 10 million articles out there comparing MyISAM to InnoDB (two so-called database engines), which Wikipedia vaguely defines as:

"...the underlying software component that a database management system (DBMS) uses to create, read, update and delete (CRUD) data from a database."

But what does that really mean? Surprisingly, I couldn't find a single article talking about the relationship of a DB to its engine!

How does an engine manifest itself in the concrete, real world? Is it that a database is really just a binary file, and that its "engine" is the .exe that handles all I/O to and from the file? Does the engine handle EXPLAIN AND QEPs?

I guess what I'm asking is: how do you define which responsibilities are MySQL's, and which activities are the responsibility of its underlying engine?

Leaseholder

I think the (Storage)Engine (in case of mysql) performs the real operation on the data. Depending on the used engine (MyISAM, InnoDB) you may get better performance for some operations. I heard (== I do not know) that MyIsam is not ACID compliant but very fast for simple writes (e.g. it would be a good consideration for a logging table). I think in general it's better (= safer) to use InnoDB. Other RDBMS do not have this concept (you cannot select the "storage engine"). – Gomphosis

A related question on an SO sister site: dba.stackexchange.com/questions/4603/… – Katzenjammer

From the manual: The storage engines themselves are the components of the database server that actually perform actions on the underlying data that is maintained at the physical server level – Monas

Answer 1

Does this picture help?

Taken from: http://forge.mysql.com/wiki/MySQL_Internals_Custom_Engine#Overview

Monas

For me it does, thanks. Together with this short explanation (linked to by Adam Houldsworth) this makes a nice answer. – Adjective