08
Tue, Oct
2 New Articles

TechTip: i Illuminate 7.3 – Time-Turner

Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

Traveling back in time is easy and can answer important questions. Take the next step with Scott on this journey through the castle.

 

Glad you could join me for episode two of this series. When I last talked to you, I had just learned what house the Sorting Hat had chosen for me. In an unexpected turn of events, I am bound for the house of Slytherin. Unlike some before me, I don’t resist the decision, bowing to the wisdom of the enchanted hat. Perhaps I’m comforted by the knowledge that my path will be influenced by future decisions that I can control.

 

My housemates welcome me with open arms and wary looks. After some time has passed, I have settled into a routine of training and competition. I am intrigued by the possibilities that lie before me. Much like my life here in the castle, DB2 for i on IBM i 7.3 provides similar opportunities for new adventures.

 

Figure 1 shows one of the most valuable additions to 7.3. DB2 for i has its own version of a “Time-Turner.” For those who have failed to read, listen to, or watch the many books, tapes, and movies that mention this device, you can read more about it here: HP Time-Turner

 

A Time-Turner is controlled by its user. When the hour glass is turned, the user is transported temporarily one hour back in time. If you need to travel further back in time, simply do the math and rotate until you reach your desired point in time.

 

042216ForstieFig1

Figure 1: Turn back the clock with DB2 for i’s Time-Turner.

 

Why bother moving back in time with DB2 for i? Because by doing so, you can easily answer important time-based questions.

 

Temporal Tables and DB2 for i

As you read about or evaluate IBM i 7.3, we expect many of you will discover use cases for system-period temporal tables. Figure 2 shows some simple examples of the realm of possibility when you can time travel with SQL on IBM i.

 

This may sound gruesome, but time travel in DB2 for i becomes possible when the database tracks the birth and death of rows. What constitutes the death of a row? Rest assured, there is no “Killing Curse” to use in the data center. Instead, when a row is updated or deleted, the previous version of the row has officially died and been laid to rest in something called a “history table.” More on that topic will be covered in the next episode of this series.

 

042216ForstieFig2

Figure 2: Here are some examples of time-based temporal (and SQL query) questions.

 

As seen in the figure, there are different coding styles that can be used to assign the period-specification of the query. Three styles of explicit time specification can be used:

 

  1. FOR SYSTEM_TIME AS OF value
    AS OF returns rows that were born before the AS OF value and did not die before the AS OF value. The value can be a literal value or an expression that includes time arithmetic.
    If the table includes a primary key, you will see at most one row returned for any specific primary key value.
  2. FOR SYSTEM_TIME FROM value1 TO value2
    FROM TO returns rows that were born before value2 and are active rows or died after value1. Again, either value can be a literal value or an expression that includes time arithmetic.
    If the table includes a primary key, you can see zero to many rows returned for any specific primary key value.
  3. FOR SYSTEM_TIME BETWEEN value1 AND value2
    BETWEEN AND returns rows that were born before or equal to value2 and are active rows or died after value1. Once again, either value can be a literal value or an expression that includes time arithmetic.
    If the table includes a primary key, you can see zero to many rows returned for any specific primary key value.

 

The figure also shows that a new CURRENT TEMPORAL SYSTEM_TIME special register can be used to avoid coding literal values in your SQL. When set to a non-NULL value, any system-time eligible applications will implicitly be treated as though they were encoded with:

 

FOR SYSTEM_TIME AS OF CURRENT TEMPORAL SYSTEM_TIME

It does not take a Transfiguration spell to get from Figure 3 to Figure 4; all you need to do is to decide to use system-period temporal table support.

 

Figure 3 depicts life before temporal table support. History is captured via user-maintained techniques. Triggers populate one or more external tracking tables, and applications were constructed to reconstruct the data to produce time-oriented analysis.

 

042216ForstieFig3

Figure 3: Do-it-yourself historical maintenance is a hassle.

 

Figure 4 shows the greatly improved solution that awaits you on IBM i 7.3. Historical triggers are revised or completely retired. Better yet, the SQL Query Engine (SQE) can be leveraged to implement time-based or time-ranged queries. As with other data-centric enhancements in the database, you can achieve real value for small effort by having the database do more for you. If you’ve never seen the term DBE, it stands for Database Engineer. The DBE is similar to a Hagrid and certainly dissimilar to “he who must not be named.”

.

042216ForstieFig4

Figure 4: The DB2 for i data-centric temporal table is so much easier!

 

Till Next Time…

This episode merely scratched the surface of how you can use system-period temporal tables with DB2 for i. Come back to read the next episode to discover how you transform your table to be temporal and other fun facts.

 

As for the wizarding world, it’s time to work on your Patronus Charm because there are dementors in the midst. Stay awake and alert!

Scott Forstie is a Senior Technical Staff Member at IBM. He is the DB2 for i Business Architect, working on all things related to the database on IBM i.  He also is the content manager of the IBM i Technology Updates wiki (www.ibm.com/developerworks/ibmi/techupdates) where IBM i operating system enhancements are described. He can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it. or followed on Twitter @ @Forstie_IBMi.

 

 

 

 

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: