Recap on the problem: A query takes a long time to complete. During this time it makes for a lot of I/O. Query's I/O overloads the db, making for other queries run slow. I introduce the notion of self-throttling queries: queries that go to sleep, by themselves, throughout the runtime. The sleep period means the [...]
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 [...]
I'm evidencing an increase in the planning, confidence & execution for MyISAM to InnoDB migration. How much can a single consultant observe? I agree Oracle should not go to PR based on my experience. But I find that: More companies are now familiar with InnoDB than there used to. More companies are interested in migration [...]
Actually this is (almost) all I wanted to say. This is intentionally posted with all related keywords in title, in the hope that a related search on Google will result with this post on first page. I'm just still encountering companies who use MyISAM as their storage engine and are unaware that their nightly backup [...]
InnoDB and MyISAM use B+ and B trees for indexes (InnoDB also has internal hash index). In both these structures, the depth of the index is an important factor. When looking for an indexed row, a search is made on the index, from root to leaves. Assuming the index is not in memory, the depth [...]
I get to hear that a lot: that LOCK TABLES with MyISAM is some sort of replacement for transactions; some model we can work with which gives us 'transactional flavor'. It isn't, and here's why. When we speak of a transactional database/engine, we check out its ACID compliance. Let's break out the ACID and see [...]
This is a short note that the MySQL User Group Meetings in Israel are established (well, re-established after a very long period). Thanks to Eddy Resnick from Sun Microsystems Israel who has set up the meetings. So far, we've had 2 successful meetings, and we intend to have more! First one was in Sun's offices [...]
"Standard SQL" is something you read about. All popular databases have modified version of SQL. Each database adds its own flavor and features to the standard. MySQL is no different.
Some deviations are storage engine dependent. Others are more general. Many, such as INSERT IGNORE, are commonly used. Here's a list of some MySQL deviations to SQL, which are not so well known.
In Part I of this article, we have seen how the internal structure of the storage engine's index can affect an execution plan. We've seen that some plans are inherent to the way engines are implemented. We wish to present a second scenario in which execution plans vary for different storage engines. Again, we will [...]
A popping question is: "Can an execution plan change for different storage engines?" The answer is "Yes". I will present two such cases, where the MySQL optimizer will choose different execution plans, based on our choice of storage engine. We will consider MyISAM and InnoDB, the two most popular engines. The two differ in many [...]