Fall is being coy this year in the Northeast. We've been having on and off spells of very mild, almost summer-like weather over the last few weeks. That trend seems to be finally ending, alas, as there is possible snow forecasted for the weekend in New Hampshire. As the old joke goes, if you don't like the weather here, just wait five minutes.

The fall also brings hunting to the area. The annual moose season just concluded (you need to enter a special lottery to get a moose permit), but deer season is just about to open. My son and I won't be participating this year, but we recently purchased the appropriate tools of the trade, a shotgun to hunt in southern NH (where you can't hunt deer with a rifle) and a Mosin Nagant 91/30 for the rest of the state. The later is probably overkill, but my son saved up his pennies to buy it, being a student of both WWII and all things …

This month marked SkySQL's first anniversary.  It also marks my 6 months with the company, after being with MySQL AB (and then Sun and finally Oracle) for over 5 years. As good a time as any for a look back and some musings of the future.

In late 2005 I took a position in the web team (a part of Marketing) at MySQL AB.  It was a great company to work for, with a great team of people and a truly great spirit.  The idea that they were making a difference every day was palpable. I then saw it taken over by Sun Microsystems and shortly after by Oracle Corporation.  We went from 500 employees to 30,000 and then to 100,000.  My job satisfaction started to decline.  I felt more like I was battling for every concession rather than revelling in what we were able to achieve.  I needed a change.

When I joined SkySQL it was like going home - I knew pretty …

Typical MySQL environment involves one Master receiving writes and multiple slaves to scale the reads. The “slave” term has been used in MySQL because the Slave servers have to perform every task in copying from the Master binlog, then updating their relay logs and finally committing to the Slave databases. The Master plays no role in replication here other than storing the replication events in the binlog.
With this kind of Master- Slave set up, there are several limitations-
-       Slave lag -       Stale or old data -       Data loss -       Manual failover which is error-prone and time consuming
In SchoonerSQL, there is no concept of “Slaves” inside synchronous cluster. We refer to it as "Read Masters" because of our synchronous approach and different replication architecture. It is …

In our last episode we looked at transactions and how to create them.  In this episode I'll look at some of the implications of transactions, especially in a web application.

Transactions and Replication

We will discuss replication in depth later in the series, however it is sufficient for the moment to say that replication allows you to copy data in near real-time between MySQL servers and keep them synchronised.  What gets transferred are the changes that are made to your tables and data. So what about rolled-back (aborted) transactions?  Since the state after the rollback is essentially the same as the state before the transaction started, there seems little point in replicating those statements.  Indeed they are not replicated. Only completed transactions are.

I briefly mentioned that …

I will be at Zendcon next week with two presentations. What’s New with MySQL will be on Wednesday the 19th and The Care and Feeding of a MySQL Database on Thursday the 20th.

Other MySQL centric session are by Bill Karwin on SQL Injection Myths and Fallacies and MySQL 5.5 InnoDB Tuning. Plus Ligaya Turmelle will present Character Sets Suck.

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“I want to ensure that the MySQL code base (under the name of MariaDB) will survive as open source, in spite of what Oracle may do.” -- Michael “Monty” Widenius. Michael “Monty” Widenius is the main author of the original version of the open-source MySQL database and a founding member of the MySQL AB company. [...]

We've now come a long way since our first steps at creating our online bookshop database. Now we need to start to think about how to sell the books and store details about the sales.  This is the time we need to start understanding database transactions.

Database transactions are very similar to real world transactions. They define a set of steps required to happen together in order for a transaction to be complete.  A real-world example might be that you buy a trinket from a store.  You find the trinket, then take it to the counter, find out the price, hand over the cash and receive your trinket.  That is a completed transaction.  Should you not have the available cash, the transaction would not be able to be completed and you would need to return the item, effectively rolling back that …

In our last episode we learned how to modify data and table definitions.  This will come in handy as we look at building in referential integrity constraints into our database.  To begin we will need the database definition resulting from last episode's changes. You can download it here »

A word on Storage Engines

Before we can begin we need to understand a little about MySQL Storage Engines.  MySQL actually does only part of the job of parsing SQL, creating query plans, executing them and returning data sets.  Where the data is stored and retrieved there is a Storage Engine at work.  The original storage engine was MyISAM, based on the industry stalwart of ISAM …