Method R

If you haven’t seen Gwen Shapira’s article about de-confusing SSD, I recommend that you read it soon.

One statement stood out as an idea on which I wanted to comment:

The first product I ever created after leaving Oracle Corporation in 1999 was a 3-day course about optimizing Oracle performance.

Early this year, my friend Mike Riley from ODTUG asked me to write a little essay in response to the question, “Why Kscope?” that he could post on the ODTUG blog. He agreed that cross-posting would help the group reach more people, so I’ve reproduced my response to that question here. I’ll hope to see you at Kscope11 in Long Beach June 26–30. If you develop applications for Oracle systems, you need to be there.

MR: Why KScope?

And now, the actual OTN interview (9:11) is online. Thank you, Justin; it was a lot of fun. And thank you to Oracle Corporation for another great show. It's an ever-growing world we work in, and I'm thrilled to be a part of it.

Today we installed two new blogs over at our method-r.com web page. We created them to give us—all of us at Method R—a place to talk about our products and professional experiences. I hope you'll come have a look.

I'll still be posting here, too.

Yesterday, Justin Kestelyn from Oracle Technology Network sent me a note specifying some logistics for our OTN interview together called “Coding for Performance, with Cary Millsap.” It will take place at Oracle OpenWorld on Monday, September 20 at 11:45am Pacific Time.

One of Justin’s requests in his note was, “Topics: Please suggest 5 topics for discussion?” So, I thought for a couple of minutes about questions I’d like him to ask me, and I wrote down the first one. And then I thought to myself that I might as well write down the answer I would hope to say to this; maybe it’ll help me remember everything I want to say. Then I wrote another question, and the answer just flowed, and then another, and another. Fifteen minutes later, I had the whole thing written out.

For the past several weeks, my team at Method R have been working hard on a new software tool that we released today. It is an extension for Oracle SQL Developer called Method R Trace. We call it MR Trace for short.

MR Trace is for SQL and PL/SQL developers who care about performance. Every time you execute code from a SQL Developer worksheet, MR Trace automatically copies a carefully scoped trace file to your SQL Developer workstation. There, you can open it with any application you want, just by clicking. You can tag it for easy lookup later. There’s a 3-minute video if you’re interested in seeing what it looks like.

At CMG'09 a couple of weeks ago, I presented "Measuring Response Times of Code on Oracle Systems." The paper for this presentation was a subset of "For Developers: Making Friends with the Oracle Database." In the presentation, I spent a few minutes talking about why to measure response times in Oracle, and then I spent a lot of minutes talking about how. As usual, I focused heavily on the importance of measuring response times of individual business tasks executed by individual end users.

The past year has been well, many words come to mind but let's go with challenging. It's also been interesting, frustrating, enlightening, exhausting, but right about now, it feels like it was a very, very good year. Those of you that have read through the previous posts will remember that, right around the time I left for the Miracle Oracle Open World conference in October of 2008, I was

As I entered the 30-minute "U.S. Citizens" queue for immigration back into the U.S. last week, the helpful "queue manager" handed me a brochure. This is a great place to hand me something to read, because I'm captive for the next 30 minutes as I await my turn with the immigration officer at the Passport Control desk. The brochure said "Roll through Customs faster."Ok. I'm listening.Inside the brochure, the first page lays out the main benefits:

• bypass the passport lines
• no paper Customs declaration
• in most major U.S. airports

Well, that's pretty cool. Especially as I'm standing only 5% deep in a queue with a couple hundred people in it. And look, there's a Global Entry kiosk right there with its own special queue, with nobody—nobody!—in it.If I had this Global Entry thing, I'd have a superpower that would enable me to zap past the couple hundred people in front of me, and get out of the Passport Control queue right now. Fantastic.So what does this thing cost? It's right there in the brochure:

1. Apply online at www.globalentry.gov. There is a non-refundable $100 application fee. Membership is valid for five years. That's $20 a year for the queue-bypassing superpower. Not bad. Still listening.
2. Schedule an in-person interview. Next, I have to book an appointment to meet someone at the airport for a brief interview.
3. Complete the interview and enrollment. I give my interview, get my photo taken, have my docs verified, and that's it, I'm done.

So, all in all, it doesn't cost too much: a hundred bucks and probably a couple hours one day next month sometime.What's the benefit of the queue-bypassing superpower? Well, it's clearly going to knock a half-hour off my journey through Passport Control. I immigrate three or four times per year on average, and today's queue is one of the shorter ones I've seen, so that's at least a couple hours per year that I'd save... Wow, that would be spectacular: a couple more hours each year in my family's arms instead of waiting like a lamb at the abattoir to have my passport controlled.But getting me into my family's arms 30 minutes earlier is not really what happens. The problem is a kind of logic that people I meet get hung up in all the time. When you think about subsystem (or resource) optimization, it looks like your latency savings for the subsystem should go straight to your system's bottom line, but that's often not what happens. That's why I really don't care about subsystem optimization; I care about response time. I could say that a thousand times, but my statement is too abstract to really convey what I mean unless you already know what I mean.What really happens in the airport story is this: if I had used Global Entry on my recent arrival, it would have saved me only a minute or two. Not half an hour, not even close.It sounds crazy, doesn't it? How can a service that cuts half an hour off my Passport Control time not get me home at least a half hour earlier?You'll understand once I show you a sequence diagram of my arrival. Here it is (at right). You can click the image to embiggen it, if you need.To read this sequence diagram, start at the top. Time flows downward. This sequence diagram shows two competing scenarios. The multicolored bar on the left-hand side represents the timeline of my actual recent arrival at DFW Airport, without using the Global Entry service. The right-hand timeline is what my arrival would have looked like had I been endowed with the Global Entry superpower.You can see at the very bottom of the timeline on the right that the time I would have saved with Global Entry is minuscule: only a minute or two.The real problem is easy to see in the diagram: Queue for Baggage Claim is the great equalizer in this system. No matter whether I'm a Global Entrant or not, I'm going to get my baggage when the good people outside with the Day-Glo Orange vests send it up to me. My status in the Global Entry system has absolutely no influence over what time that will occur.Once I've gotten my baggage, the Global Entry superpower would have again swung into effect, allowing me to pass through the zero-length queue at the Global Entry kiosk instead of waiting behind two families at the Customs queue. And that's the only net benefit I would have received.Wait: there were only two families in the Customs queue? What about the hundreds of people I was standing behind in the Passport Control queue? Well, many of them were gone already (either they had hand-carry bags only, or their bags had come off earlier than mine). Many others were still awaiting their bags on the Baggage Claim carousel. Because bags trickle out of the baggage claim process, there isn't the huge all-at-once surge of demand at Customs that there is at Passport Control when a plane unloads. So the queues are shorter.At any rate, there were four queues at Customs, and none of them was longer than three or four families. So the benefit of Global Entry—in exchange for the $100 and the time spent doing the interview—for me, this day, would have been only the savings of a couple of minutes.Now, if—if, mind you—I had been able to travel with only carry-on luggage, then Global Entry would have provided me significantly more value. But when I'm returning to the U. S. from abroad, I'm almost never allowed to carry on any bag other than my briefcase. Furthermore, I don't remember ever clearing Passport Control to find my bag waiting for me at Baggage Claim. So the typical benefit to me of enrolling in Global Entry, unfortunately, appears to be only a fraction of the duration required to clear Customs, which in my case is almost always approximately zero.The problem causing the low value (to me) of the Global Entry program is that the Passport Control resource hides the latency of the Baggage Claim resource. No amount of tuning upon the Passport Control resource will affect the timing of the Baggage In Hand milestone; the time at which that milestone occurs is entirely independent of the Passport Control resource. And that milestone—as long as it occurs after I queue for Baggage Claim—is a direct determinant of when I can exit the airport. (Gantt or PERT chart optimizers would say that Queue for Baggage Claim is on the critical path.)How could a designer make the airport experience better for the customer? Here are a few ideas:

• Let me carry on more baggage. This idea would allow me to trot right through Baggage Claim without waiting for my bag. In this environment, the value of Global Entry would be tremendous. Well, nice theory; but allowing more carry-on baggage wouldn't work too well in the aggregate. The overhead bins on my flight were already stuffed to maximum capacity, and we don't need more flight delays induced by passengers who bring more stuff onboard than the cabin can physically accommodate.
• Improve the latency of the baggage claim process. The sequence diagram shows clearly that this is where the big win is. It's easy to complain about baggage claim, because it's nearly always noticeably slower than we want it to be, and we can't see what's going on down there. Our imaginations inform us that there's all sorts of horrible waste going on.
• Use latency hiding to mask the pain of the baggage claim process. Put TV sets in the Baggage Claim area, and tune them to something interesting instead of infinite loops of advertising. At CPH, they have a Danish hot dog stand in the baggage claim area. They also have a currency exchange office in there. Excellent latency hiding ideas if you need a snack or some DKK walkin'-around-money.

Latency hiding is a weak substitute for improving the speed of the baggage claim process. The killer app would certainly be to make Baggage Claim faster. Note, however, that just making Baggage Claim a little bit faster wouldn't make the Global Entry program any more valuable. To make Global Entry any more valuable, you'd have to make Baggage Claim fast enough that your bag would be waiting for anyone who cleared the full Passport Control queue.So, my message today: When you optimize, you must first know your goal. So many people optimize subsystems (resources) that they think are important, but optimizing subsystems is often not a path to optimizing what you really want. At the airport, I really don't give a rip about getting out of the Passport Control queue if it just means I'm going to be dumped earlier into a room where I'll have to wait until an affixed time for my baggage.Once you know what your real optimization goal is (that's Method R step 1), then the sequence diagram is often all you need to get your breakthrough insight that either helps you either (a) solve your problem or (b) understand when there's nothing further that you can really do about it.