Difference between Views & Materialized views

Difference between Views & Materialized views

Materialized views are disk based and update periodically base upon the query definition.

Views are virtual only and run the query definition each time they are accessed.

Views evaluate the data in the tables underlying the view definition at the time the view is queried. It is a logical view of your tables, with no data stored anywhere else. The upside of a view is that it will always return the latest data to you. The downside of a view is that its performance depends on how good a select statement the view is based on. If the select statement used by the view joins many tables, or uses joins based on non-indexed columns, the view could perform poorly.

Materialized views are similar to regular views, in that they are a logical view of your data (based on a select statement), however, the underlying query resultset has been saved to a table. The upside of this is that when you query a materialized view, you are querying a table, which may also be indexed. In addition, because all the joins have been resolved at materialized view refresh time, you pay the price of the join once (or as often as you refresh your materialized view), rather than each time you select from the materialized view. In addition, with query rewrite enabled, Oracle can optimize a query that selects from the source of your materialized view in such a way that it instead reads from your materialized view. In situations where you create materialized views as forms of aggregate tables, or as copies of frequently executed queries, this can greatly speed up the response time of your end user application. The downside though is that the data you get back from the materialized view is only as up to date as the last time the materialized view has been refreshed.

Materialized views can be set to refresh manually, on a set schedule, or based on the database detecting a change in data from one of the underlying tables. Materialized views can be incrementally updated by combining them with materialized view logs, which act as change data capture sources on the underlying tables.

Materialized views are most often used in data warehousing / business intelligence applications where querying large fact tables with thousands of millions of rows would result in query response times that resulted in an unusable application.

Introduction to Business Intelligence

What is business intelligence?

The term Business Intelligence – often referred to simply as BI – was originally coined by Gartner Group who in 1996 wrote:

By 2000, Information Democracy will emerge in forward-thinking enterprises, with Business Intelligence information and applications available broadly to employees, consultants, customers, suppliers, and the public. The key to thriving in a competitive marketplace is staying ahead of the competition. Making sound business decisions based on accurate and current information takes more than intuition. Data analysis, reporting, and query tools can help business users wade through a sea of data to synthesize valuable information from it - today these tools collectively fall into a category called "Business Intelligence."

In other words, Business Intelligence (BI) is a terminology representing a collection of processes, tools and technologies helpful in achieving more profit by considerably improving the productivity, sales and service of an enterprise. With the help of BI methods, the corporate data can be organized, analyzed in a better way and then converted into a useful knowledge of information needed to initiate a profitable business action. Thus it’s about turning a raw, collected data into intelligent information by analyzing and re-arranging the data according to the relationships between the data items by knowing what data to collect and manage and in what context.

A company's collected raw data is an important asset where one can find solutions to many of an organization’s critical questions like 'what was the net profit for a particular product last year and what will be sales this year and what are the key factors to be focused this year in order to increase the sales?'. So there arises a necessity of a well planned BI system which can lead to a greater profitability by reducing the operating costs, increasing the sales and thereby improving the customer satisfaction for an enterprise.

With the help of a Business Intelligence System, a company may improve its business or rule over its competitors by exploring and exploiting its data to know the customer preferences, nature of customers, supply chains, geographical influences, pricings and how to increase its overall business efficiency.

Why is business intelligence needed?

BI is about analyzing an organization’s performance in order to improve its income and competitiveness. Thus, in a sense BI is something organizations have always been involved with BI on some level. With today’s modern IT systems however, organizations are collecting ever increasing volumes of data and it is no longer possible to analyze such data without specialized tools and methods. The data will not fit inside a person’s head.

Business Intelligence tools let users sip efficiently through huge amounts in a matter of seconds. Such impressive response times are not simply given by modern hardware and software. Special architectures and methods for building such systems are required.

Business Intelligence tools let users sip efficiently through huge amounts in a matter of seconds. Such impressive response times are not simply given by modern hardware and software. Special architectures and methods for building such systems are required.

Facebook Acquires Location-Based Service Glancee

Facebook has scooped up another startup in its path toward mobile dominance. This time, it’s Glancee, an ambient location-based service that competes with Highlight. 



From Glancee’s home page:


“We started Glancee in 2010 with the goal of bringing together the best of your physical and digital worlds. We wanted to make it easy to discover the hidden connections around you, and to meet interesting people. Since then Glancee has connected thousands of people, empowering serendipity and pioneering social discovery.


“We are therefore very excited to announce that Facebook has acquired Glancee and that we have joined the team in Menlo Park to build great products for over 900 million Facebook users. We’ve had such a blast connecting people through Glancee, and we truly thank our users for being a part of the Glancee community.”



Less than a month ago, Facebook acquired the mobile-based photo-sharing app Instagram for $1 billion, and the world’s largest social network has expressed its sights are set on mobile.


Glancee fits the bill. It was one of the hot passive location startups at SXSW this year, along with Highlight and Sonar.


Facebook’s just weeks away from an initial public offering. The company announced its shares would be priced at $28 to $35, putting the company at a valuation of $85 billion and $95 billion. Facebook did not disclose the terms of the Glancee acquisition.

Instagram Passes 50 Million Users

The photo-sharing app is on fire. It now has more than 50 million users — and is adding new ones at the rate of roughly 5 million per week, according to its API. 


Instagram hit 40 million users around April 13, and 30 million at the start of the month. This is astonishing growth for an app that started 2012 with just 15 million users.


Of course, the fact that the app was recently released for Android — after being iPhone-only for its first two years — is likely driving a lot of those sign-ups. But Instagram also hit number one in the iOS App store for the first time in the wake of the Facebook acquisition.


Some time ago Facebook reported that it was up to buy Instagram, a 2-year-old photo-sharing application developer, in its largest-ever acquisition just months before the social media website is expected to go public.



“For years, we’ve focused on building the best experience for sharing photos with your friends and family,” Facebook founder Mark Zuckerberg said while announcing the deal. “Now, we’ll be able to work even more closely with the Instagram team to also offer the best experiences for sharing beautiful mobile photos with people based on your interests.”


Facebook CEO called the acquisition “an important milestone for Facebook because it’s the first time we’ve ever acquired a product and company with so many users. We don’t plan on doing many more of these, if any at all.”


Seemingly, the buyout has also helped to drive interest and it probably won’t be long until the firm hits the 100 million milestone.

Facebook to encourage organ donation

Facebook on Tuesday unveiled an organ donor status option for Timeline, a move designed to help more than 114,000 people in the U.S. and millions more around the world who are waiting for a life-saving heart, kidney or liver transplant.


“Many of those people — an average of 18 people per day –- will die waiting, because there simply aren’t enough organ donors to meet the need,” Facebook notes in a blog entry explaining the move. “Medical experts believe that broader awareness about organ donation could go a long way toward solving this crisis.”


Designating yourself as an organ donor is easy. All you need to do is go to your Timeline, click on “Life Event” and then “Health & Wellness.” Then, you’ll see the option for “Organ Donor.” At that point, you can add when and where you registered and your personal story.


For those who aren’t organ donors, Facebook is providing a link to the appropriate registry. As with other Timeline entries, you can make your organ donor status public or private.


While the plan might initially seem strange, it's quite clever once you think about it. Whether we love or hate Facebook, the social network plays a role in many of our lives. So when an issue is promoted on the site, we won't be able to escape it. Soon you'll notice the option to add your organ donation status when you edit your Timeline, you'll see your friends adding such statuses and you'll see links encouraging you to officially register as a donor. 


Odds are, you'll idly click on something and learn a bit about organ donation. You might even decide to become a donor yourself — and then update your Facebook status, of course — which will add to the overall promotion of the issue.


Whether the awareness raised by Facebook (as well as the peer pressure it produces) will reduce the number of individuals who die while waiting for a transplant remains to be seen.