|By Tom Peer||
|April 8, 2002 12:00 AM EDT||
[Ed. Note: We've run articles on this in the past, but - we can never say it enough!]
Cutting ColdFusion code is fun, and therein lies ColdFusion's biggest problem. It's too easy to get carried away writing code to do things that should be happening in the database itself - or often shouldn't be happening at all. It's also just too easy to use. You can get up and running far too quickly, and get into trouble even quicker. Sometimes experienced developers get carried away trying to do too much; beginners often start to run before they can walk.
When I came across a site where a simple query of news stories was taking a quarter of a second, I wasn't sure that writing their own object-caching mechanism in ColdFusion was entirely the right approach. I called a timeout - a morning to go over the basics. One simple run of the Query Analyzer diagnosed the problem: a date field was being used in a sort clause without an index.
The query time was reduced to around 15ms - around 6ms database time plus the ODBC overhead. If you use SQL Server, the Query Analyzer is a tool you should learn to love. As a basic rule, any query that does more than select a single record using a primary as the criterion will probably benefit from some sort of index.
Using it couldn't be simpler - simply open a window, enter your SQL query text and then press Ctrl + I to run an index analysis (see Figure 1). In SQL Server versions 7 and up it's become an invaluable tool. You can also take a look at the path analysis and turn on the "Show stats time" option in the Query->Current Connection Options dialog.
It's useful, but in a publishing application there's only so much you can do to tune database performance. You can get too worried about optimization - you're pushing about large text strings and that takes time. Hard-core optimization is more relevant in financial and engineering applications where the database is summarizing and calculating vast numbers of small records.
You're more likely to achieve better results if you concentrate your efforts on your ColdFusion code. ColdFusion offers two powerful ways of caching queries: the "cached within" feature and caching in a shared scope. Many developers aren't aware that you can cache any ColdFusion object in the application scope; structs and queries can just as easily be cached as scalar variables. You can cache queries that are unlikely to change in application.cfm:
<cfif NOT IsDefined("application.courses")>
<cflock scope="application" type="exclusive" timeout="10">
<cfquery name="courses" datasource="#application.dsn#">
SELECT * FROM COURSES
ORDER BY COURSE
<cfset application.courses = courses>
<cflock scope="application" type="exclusive" timeout="10">
(The locking after the query is vitally important; see article 20370 in the ColdFusion knowledgebase.)
By putting the actual query and assignment above into a separate include file and calling it whenever the table is affected, you can create your own full-fledged cache server. Alternatively, you can convert the query to a struct keyed by the primary key of the database table and put the struct into the application scope. There are custom tags in the developer's exchange to do this, but it's almost quicker to do it yourself.
Don't be scared of using the application scope. Memory's cheap and downtime isn't. If your entire database is only half a gigabyte and you have 2GB in your server, why not load it into the application scope?
Usually it's best to mix this approach with the cached within approach. Say you have a database of two thousand suppliers, listed by region, together with the services they offer. You want to use the "startrow, endrow" parameters of <CFOUTPUT> to show fifty at a time, but this means fetching the entire listing in the query, which takes nearly 150ms.
In this case you could put the fields you need for the listing in an application-level query and then, on a separate "view" page, select the main details in a separate query that you apply the cached within parameter to. This parameter of <CFQUERY> is one of ColdFusion's best features. It can send your sysadmin into a blind panic when he or she sees CF taking up 800MB ("It's got a leak!"), but it's so simple to use compared to rival offerings.
One technique I use all the time, caching formatted output, is a little more contentious. Say, for instance, you have fields in your supplier database for TEL, FAX, EMAIL, WEB - any of which may be blank or need formatting. In a listing page of fifty records this can take time. On one of my pages it was taking too much time just to do a simple list. My solution? Rather than copy the whole query into the application scope, I created a new query (see the Query-New() function) with fields for the primary key and formatted display.
Even more contentious: sometimes I put the formatted output back into the database. I do this all the time where the database is storing XML and I need to convert to HTML. Converting a page on the fly takes around 400ms (assuming XSL doesn't get stuck in an endless loop) and displaying a cached query takes less than 1ms.
This may sound like a lash-up (I less than impressed an old college friend who followed a slightly more formal career), but this is how the really expensive application servers work. Sure, they won't store large chunks of HTML in the database; they'll store serialized Java objects, but at least the HTML will still work when somebody changes the code. (Application servers store objects in a format that depends on the object definition [your code]. When you change that definition, the entire object store can be rendered unusable. It's very problematic, and I've seen plenty of implementations of expensive object servers where almost all the data is stored in plain SQL tables.)
Note: With reference to Ben Forta's February CFDJ article ("Faster and Safer Database Queries," Vol. 4, issue 2), you can't cache a query that uses a QUERYPARAM tag. You can, though, achieve the same security against malicious URLs by ensuring that all your tables have a numeric primary key and then validating any variables used in SQL queries with an "IsNumeric()" test. It's one more reason why all database tables should have a numeric primary key.
No matter how cheap memory gets, you do still need to apply a certain amount of discipline to your coding. One of the most common causes of database problems is fetching too much data from the database. Using derived tables and other advanced SQL constructs, you should be able to avoid fetching vast amounts of query data and looping over it.
A typical derived table query looks something like this:
SELECT TOP 1 A.NEWS_ID, A.HEADLINE, A.STORY FROM NEWS AS A,
(SELECT NEWS_ID FROM NEWS_CATEGORIES_JOIN
WHERE CATEGORY_ID IN (#cat_list#)) AS B
WHERE A.NEWS_ID = B.NEWS_ID
ORDER BY A.PUBDATE DESC
This will select a record from a correctly built many-to-many join (of which much more later) when a GROUP BY can't be used (i.e., with long text fields). This is just a simple example (a subselect could be used equally well here and run as quickly); derived tables are most effective when some sort of calculation needs to be performed, perhaps a summation or a count. If you find the idea of working with tables that don't exist a little frightening, you can often achieve the same affect by using a view, a stored query that can be queried and joined just like a standard table (see Figure 2).
Often underused, views are a great tool for making both your SQL and your CF code as simple as possible. They're second nature to anyone who's come to SQL Server from Access (where they're known as queries), but experienced programmers who have been using old-style databases often prefer to do everything in one query. Using views is usually quicker than performing joins or summaries at runtime. I saw a job advertisement recently that said "must be able to write join queries without using visual tools" and I thought: "Why?" There's no benefit, save a few techy kudos.
If you do need to loop over entire tables, try to avoid fetching the data into ColdFusion. Database cursors (described by Ian Rutherford in "Using MS-SQL Stored Procedures with ColdFusion," CFDJ Vol. 4, issue 2) will run much faster than dragging data into ColdFusion, processing it, and then running an update. It also won't take up a ColdFusion thread or valuable network capacity.
Speed Isn't Everything
As important as optimization is, sometimes there's too much focus on saving a millisecond here or cutting down white space there at the expense of properly structured code and databases. The key to software engineering, as in all engineering, is to keep it simple, and the main aim in a ColdFusion development should be no different from any other project: to keep the code to a minimum.
It's this discipline of keeping things simple that's the most important part of building reliable and scalable sites. It may seem strange, but sometimes code that runs slower can make for better Web sites. Take, for example, what for me is the litmus test of good database design: the use of many-to-many joins. A typical database application might be a listing of schools and the courses they offer. The original data, as always, is in Excel, looking something like the example in Figure 3. The experienced developer will recognize the need for a separate table of courses and a third "join" table indicating which schools have which courses.
The temptation, though, is simply to import it into the database and use it as is, relying on ColdFusion's list handling to determine which courses are offered by which schools. That would be bad, but what would be even worse would be some attempt to code the courses offered as separate database fields (see Figure 4).
Why you shouldn't do this is hard to explain, although it's simple: in a SELECT query it'll run two to three times as fast as using a many-to-many join, and it's easy to program using ColdFusion Studio. You just point the wizards at the right table and five minutes later you're done. But by doing something like this, you have hard-coded "data" into the "structure" of your system. To build truly scalable systems, you need to keep a very definite division between the structure and the data. The Golden Rule is this: if your ColdFusion code is completely separate from your database, then your system will scale. If you've hard-coded data as fieldnames - you just can't do this - your data is inextricably tied up with your application.
Using ColdFusion, it isn't always possible to adhere to the strict three-tier model (database, application, presentation), but creating a division between the structure and the data is still a must. You should be able to edit the data directly without using your ColdFusion application and still see the changes reflected on your site.
So, for instance, were you to add a new course to the table of courses, your site should display that course wherever relevant. Often this doesn't happen; data fields are hard-coded and the layout of the pages is dependent on the data structure.
Sometimes you might use the ColdFusion application to enforce certain database rules - for instance, that a salesperson can have a maximum of only 10 customers. This is fine. In fact, database theorists call such a rule an application rule for the very reason that it doesn't affect the underlying data. If a salesperson had 11 clients it wouldn't affect the data in any way. But if the only way you could add or remove clients was through the ColdFusion-based Web interface, then something would be amiss.
A simple example like the one shown in Figure 4 doesn't really illustrate the necessity of relational design. Once you're bug-free, the example will run faster than a relational design, and it will scale. It's simple and, above all, that's what matters.
You wouldn't have to get much more complicated before a flat file system like this would start to break down, though. It's not just raw performance that's the issue - the extra complexity of the code and the difficulties in making changes will all contribute in different ways to a lack of scalability. If a system relies on a single overworked developer to make simple changes, then it won't be scalable no matter how optimized the code.
As with any rule, the one about keeping the data separate from the code is easily broken. It's quite possible to make such a convoluted mess of triggers, derived tables, cursor loops, and other database constructs that no amount of processing power will save you. Keep it simple, though, and it will scale.
Easy in Theory
Although it makes things simpler in the database system, relational design can, if you're not careful, make things more complicated in the Web application. Using separate tables for many-to-many joins requires extra INSERT queries, and SELECT functions often have to employ grouping, subselects, or derived tables.
Perhaps the principal reason many-to-many joins don't get used is that most database editing systems don't have a standard component for implementing them. Access doesn't (you have to create a subform or use some VB), and if you're using HTML forms, you unfortunately can't use the "query" attribute of <CFSELECT> as it doesn't support multiple values for "selected". You can, however, use a simple loop:
<cfselect name="course_id" multiple="Yes">
DE("selected"), DE(""))# value="#courses_id#">#course#
Alternatively, you can use checkboxes; another effective device for editing many-to-many joins is a swap box. It's especially useful when you have many possible options to choose from, and it's more intuitive than multiple select boxes where the user has to control-click (see Figure 5).
There are several custom tags to do this in the developer's exchange, and my own <CF_SWAPBOX> is available from my site (see "Resources" section). It has almost identical syntax to CFSELECT, and also supports multiple values for "selected".
One thing you can't do much about is the complexity of inserting and updating the "join" tables (the third table used for many-to-many joins). You can cut down the number of queries needed by using an "insert into" with a subselect, for example:
INSERT INTO COURSES_SCHOOLS_JOIN
SELECT COURSES_ID, #form.SCHOOLS_ID#
WHERE COURSES_ID IN (#form.courses_id#)
but this won't run any faster than using multiple inserts in the same query. Nor can you run this as a stored procedure (you can't pass a list of integer primary keys as a VARCHAR and then use it in a subselect), nor can you use the <CFQUERYPARAM> tag. It's best just to run a separate insert for each row of the join table.
Perhaps, though, the biggest obstacle to correct database design isn't a technical one, but the very familiar problem of client demands. Before you can build a sound database, you need to convince the client that that's what's needed. The temptation for clients is to think of their Web site like a magazine: "I want to put that over there, that over there." Convincing clients they need to "think data" is the hardest part of any project.
In the most difficult project I ever worked on, the editor of the site was so incensed at no longer being able to work on the HTML pages himself that he got hold of the administrator password and replaced all the ColdFusion code with HTML pages he'd "saved as" from his browser. All the dynamic functions duly broke, but because the site still looked the same as it did before, the client never really understood what had happened. As far as he was concerned, my code didn't work. The editor was there to edit pages and that was what he was doing.
The concept of changing a page not by editing the page itself, but by editing a separate data system, is a surprisingly difficult conceptual hurdle for many people. It's such a simple concept that it's easy to forget how revolutionary it is. Those who have come from a print media background aren't going to buy into the database idea until they've had that hallelujah moment and seen just what an impact information systems can have. Until that time they're going to find using a database frustrating and too inflexible.
If your client isn't of the database mind-set when you start a project, it's vital that you help him or her see the light before you start programming. Otherwise you'll end up putting in hooks and hacks to try and satisfy client demands ("sometimes we might want to do something different"). They'll come back to haunt you.
I've found that the most important ingredient of a successful site isn't the design or my code, but getting the client used to the idea of editing a database. A client who comes to you not with ideas for "new pages" but a "new section" and a sketch of the underlying data is worth more than any amount of milliseconds saved from a database query.
SYS-CON Events announced today that IceWarp will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. IceWarp, the leader of cloud and on-premise messaging, delivers secured email, chat, documents, conferencing and collaboration to today's mobile workforce, all in one unified interface
Aug. 31, 2015 04:00 AM EDT Reads: 403
WebRTC has had a real tough three or four years, and so have those working with it. Only a few short years ago, the development world were excited about WebRTC and proclaiming how awesome it was. You might have played with the technology a couple of years ago, only to find the extra infrastructure requirements were painful to implement and poorly documented. This probably left a bitter taste in your mouth, especially when things went wrong.
Aug. 31, 2015 02:00 AM EDT Reads: 449
Too often with compelling new technologies market participants become overly enamored with that attractiveness of the technology and neglect underlying business drivers. This tendency, what some call the “newest shiny object syndrome,” is understandable given that virtually all of us are heavily engaged in technology. But it is also mistaken. Without concrete business cases driving its deployment, IoT, like many other technologies before it, will fade into obscurity.
Aug. 30, 2015 10:00 PM EDT Reads: 348
While many app developers are comfortable building apps for the smartphone, there is a whole new world out there. In his session at @ThingsExpo, Narayan Sainaney, Co-founder and CTO of Mojio, will discuss how the business case for connected car apps is growing and, with open platform companies having already done the heavy lifting, there really is no barrier to entry.
Aug. 30, 2015 05:00 PM EDT Reads: 134
As more intelligent IoT applications shift into gear, they’re merging into the ever-increasing traffic flow of the Internet. It won’t be long before we experience bottlenecks, as IoT traffic peaks during rush hours. Organizations that are unprepared will find themselves by the side of the road unable to cross back into the fast lane. As billions of new devices begin to communicate and exchange data – will your infrastructure be scalable enough to handle this new interconnected world?
Aug. 30, 2015 04:00 PM EDT Reads: 155
SYS-CON Events announced today that Micron Technology, Inc., a global leader in advanced semiconductor systems, will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Micron’s broad portfolio of high-performance memory technologies – including DRAM, NAND and NOR Flash – is the basis for solid state drives, modules, multichip packages and other system solutions. Backed by more than 35 years of technology leadership, Micron's memory solutions enable the world's most innovative computing, consumer,...
Aug. 30, 2015 01:30 PM EDT Reads: 223
SYS-CON Events announced today that Pythian, a global IT services company specializing in helping companies leverage disruptive technologies to optimize revenue-generating systems, has been named “Bronze Sponsor” of SYS-CON's 17th Cloud Expo, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. Founded in 1997, Pythian is a global IT services company that helps companies compete by adopting disruptive technologies such as cloud, Big Data, advanced analytics, and DevOps to advance innovation and increase agility. Specializing in designing, imple...
Aug. 30, 2015 01:00 PM EDT Reads: 293
SYS-CON Events announced today that HPM Networks will exhibit at the 17th International Cloud Expo®, which will take place on November 3–5, 2015, at the Santa Clara Convention Center in Santa Clara, CA. For 20 years, HPM Networks has been integrating technology solutions that solve complex business challenges. HPM Networks has designed solutions for both SMB and enterprise customers throughout the San Francisco Bay Area.
Aug. 30, 2015 10:30 AM EDT Reads: 878
Consumer IoT applications provide data about the user that just doesn’t exist in traditional PC or mobile web applications. This rich data, or “context,” enables the highly personalized consumer experiences that characterize many consumer IoT apps. This same data is also providing brands with unprecedented insight into how their connected products are being used, while, at the same time, powering highly targeted engagement and marketing opportunities. In his session at @ThingsExpo, Nathan Treloar, President and COO of Bebaio, will explore examples of brands transforming their businesses by t...
Aug. 30, 2015 10:15 AM EDT Reads: 229
With the proliferation of connected devices underpinning new Internet of Things systems, Brandon Schulz, Director of Luxoft IoT – Retail, will be looking at the transformation of the retail customer experience in brick and mortar stores in his session at @ThingsExpo. Questions he will address include: Will beacons drop to the wayside like QR codes, or be a proximity-based profit driver? How will the customer experience change in stores of all types when everything can be instrumented and analyzed? As an area of investment, how might a retail company move towards an innovation methodolo...
Aug. 30, 2015 09:15 AM EDT Reads: 444
Through WebRTC, audio and video communications are being embedded more easily than ever into applications, helping carriers, enterprises and independent software vendors deliver greater functionality to their end users. With today’s business world increasingly focused on outcomes, users’ growing calls for ease of use, and businesses craving smarter, tighter integration, what’s the next step in delivering a richer, more immersive experience? That richer, more fully integrated experience comes about through a Communications Platform as a Service which allows for messaging, screen sharing, video...
Aug. 30, 2015 09:15 AM EDT Reads: 627
The Internet of Things (IoT) is about the digitization of physical assets including sensors, devices, machines, gateways, and the network. It creates possibilities for significant value creation and new revenue generating business models via data democratization and ubiquitous analytics across IoT networks. The explosion of data in all forms in IoT requires a more robust and broader lens in order to enable smarter timely actions and better outcomes. Business operations become the key driver of IoT applications and projects. Business operations, IT, and data scientists need advanced analytics t...
Aug. 30, 2015 08:30 AM EDT Reads: 398
A producer of the first smartphones and tablets, presenter Lee M. Williams will talk about how he is now applying his experience in mobile technology to the design and development of the next generation of Environmental and Sustainability Services at ETwater. In his session at @ThingsExpo, Lee Williams, COO of ETwater, will talk about how he is now applying his experience in mobile technology to the design and development of the next generation of Environmental and Sustainability Services at ETwater.
Aug. 30, 2015 07:00 AM EDT Reads: 120
As more and more data is generated from a variety of connected devices, the need to get insights from this data and predict future behavior and trends is increasingly essential for businesses. Real-time stream processing is needed in a variety of different industries such as Manufacturing, Oil and Gas, Automobile, Finance, Online Retail, Smart Grids, and Healthcare. Azure Stream Analytics is a fully managed distributed stream computation service that provides low latency, scalable processing of streaming data in the cloud with an enterprise grade SLA. It features built-in integration with Azur...
Aug. 28, 2015 07:45 PM EDT Reads: 210
Akana has announced the availability of the new Akana Healthcare Solution. The API-driven solution helps healthcare organizations accelerate their transition to being secure, digitally interoperable businesses. It leverages the Health Level Seven International Fast Healthcare Interoperability Resources (HL7 FHIR) standard to enable broader business use of medical data. Akana developed the Healthcare Solution in response to healthcare businesses that want to increase electronic, multi-device access to health records while reducing operating costs and complying with government regulations.
Aug. 26, 2015 07:00 AM EDT Reads: 133
For IoT to grow as quickly as analyst firms’ project, a lot is going to fall on developers to quickly bring applications to market. But the lack of a standard development platform threatens to slow growth and make application development more time consuming and costly, much like we’ve seen in the mobile space. In his session at @ThingsExpo, Mike Weiner, Product Manager of the Omega DevCloud with KORE Telematics Inc., discussed the evolving requirements for developers as IoT matures and conducted a live demonstration of how quickly application development can happen when the need to comply wit...
Aug. 2, 2015 11:15 AM EDT Reads: 553
The Internet of Everything (IoE) brings together people, process, data and things to make networked connections more relevant and valuable than ever before – transforming information into knowledge and knowledge into wisdom. IoE creates new capabilities, richer experiences, and unprecedented opportunities to improve business and government operations, decision making and mission support capabilities.
Aug. 1, 2015 10:00 AM EDT Reads: 479
Explosive growth in connected devices. Enormous amounts of data for collection and analysis. Critical use of data for split-second decision making and actionable information. All three are factors in making the Internet of Things a reality. Yet, any one factor would have an IT organization pondering its infrastructure strategy. How should your organization enhance its IT framework to enable an Internet of Things implementation? In his session at @ThingsExpo, James Kirkland, Red Hat's Chief Architect for the Internet of Things and Intelligent Systems, described how to revolutionize your archit...
Jul. 30, 2015 07:30 PM EDT Reads: 1,565
MuleSoft has announced the findings of its 2015 Connectivity Benchmark Report on the adoption and business impact of APIs. The findings suggest traditional businesses are quickly evolving into "composable enterprises" built out of hundreds of connected software services, applications and devices. Most are embracing the Internet of Things (IoT) and microservices technologies like Docker. A majority are integrating wearables, like smart watches, and more than half plan to generate revenue with APIs within the next year.
Jul. 30, 2015 02:30 PM EDT Reads: 279
Growth hacking is common for startups to make unheard-of progress in building their business. Career Hacks can help Geek Girls and those who support them (yes, that's you too, Dad!) to excel in this typically male-dominated world. Get ready to learn the facts: Is there a bias against women in the tech / developer communities? Why are women 50% of the workforce, but hold only 24% of the STEM or IT positions? Some beginnings of what to do about it! In her Opening Keynote at 16th Cloud Expo, Sandy Carter, IBM General Manager Cloud Ecosystem and Developers, and a Social Business Evangelist, d...
Jul. 30, 2015 12:00 PM EDT Reads: 2,230