MyISAM versus InnoDB [closed]

manpreet Best Answer 3 years ago

I'm working on a projects which involves a lot of database writes, I'd say (70% inserts and 30% reads). This ratio would also include updates which I consider to be one read and one write. The reads can be dirty (e.g. I don't need 100% accurate information at the time of read).
The task in question will be doing over 1 million database transactions an hour.

I've read a bunch of stuff on the web about the differences between MyISAM and InnoDB, and MyISAM seems like the obvious choice to me for the particular database/tables that I'll be using for this task. From what I seem to be reading, InnoDB is good if transactions are needed since row level locking is supported.

Does anybody have any experience with this type of load (or higher)? Is MyISAM the way to go?

manpreet 3 years ago

People often talk about performance, reads vs. writes, foreign keys, etc. but there's one other must-have feature for a storage engine in my opinion: atomic updates.

Try this:

1. Issue an UPDATE against your MyISAM table that takes 5 seconds.
2. While the UPDATE is in progress, say 2.5 seconds in, hit Ctrl-C to interrupt it.
3. Observe the effects on the table. How many rows were updated? How many were not updated? Is the table even readable, or was it corrupted when you hit Ctrl-C?
4. Try the same experiment with UPDATE against an InnoDB table, interrupting the query in progress.
5. Observe the InnoDB table. Zero rows were updated. InnoDB has assured you have atomic updates, and if the full update could not be committed, it rolls back the whole change. Also, the table is not corrupt. This works even if you use killall -9 mysqld to simulate a crash.

Performance is desirable of course, but not losing data should trump that.