Disclaimer

All of the topics discussed here in this blog comes from my real life encounters. They serve as references for future research. All of the data, contents and information presented in my entries have been altered and edited to protect the confidentiality and privacy of the clients.

Saturday, October 12, 2013

A comprehensive way to understand Oracle BI Apps

As you spend more time developing reports using OBIEE, you will realize that the needs for better and more optimized data models and ETL frameworks become more important. You realize that most of the time required to spend is on designing database schemas, tables and objects as well as ETL frameworks to load the data into analytic warehouse. Needless to say, the time required to research and understand the specific business process and subject matter is more crucial than the technical implementation. Often, millions of dollars and years of time are invested in this matter, but still things can go wrong. This is the price people pay when it invent the wheel.

What if there is a complete, end-to-end solution for any specific business needs that are pre-engineered and packaged for you, which can be deployed and installed in your system fairly simply, that will save you endless times and risk of mistakes? This is what BI Apps is all about. With a complete end-to-end structure that consists of the groundwork of analytic warehouse where all the required schemas and objects have been created, the most optimized ETL framework that takes care of all the data transformation needs, and most eye-catching reports and dashboards with the most valuable information displayed in highly visual and communicative ways. Most importantly, BI App is a project after years of research and engineering that are designed to solve most of the problems for business. In other words, the wheel is already invented, you just need to put it on your car. This is the reason why BI Apps have become the solution for so many companies, it's all about cost-effectiveness.

In order to understand how BI Apps work and how to study and gain more insight about it, you should first start thinking in terms of problems and how BI Apps solves them. If you were just trying to study and memorize things by reading documents, it is hard.

So start asking yourself these questions:

1. Knowing that BI Apps is an end-to-end solution package that comes with a pre-build data warehouse, Pre-defined Informatica framework, DAC and OBIEE, what does it take to put these things in your business so it can be operating? In other words, should I install all these things on 1 machine or multiple machines?

hint: Informatica and DAC have to be installed on the same machine. OBIEE has to be on different machine. Staging DB and warehouse can be on 1 machine. Since OBIEE's admin tool is a windows based application, a windows machine is needed to install OBIEE client tool so that the pre-build OBIEE objects (rpd) of the BI Apps can be installed. 

2. Once this thing is installed, it is not running yet. Which means, your live data from OLTP is not yet being loaded into your warehouse, so none of the OBIEE reports will work. How does BI Apps pull data from your OLTP source, if your OLTP source is Siebel, Peoplesoft, EBS, JD Edwards or your home grown one?

Hint: Oracle provides adapter for pulling data from various sources. If you open the Informatica repository, you will see a list of Adapters available. These are nothing but folders where different mappings are stored. If your source is EBS, then you will use EBS adapter where all of the informatica mappings are pre-built to pull data from EBS source. All of the source table definitions there will match exactly with the tables in your EBS. If you use home-grown source, then there is universal adapter for you where the input files will have to be customized into CSV format for Informatica to load from. 

3. One you start loading data into your warehouse, how does BI Apps actually do it successfully based on your needs? If you think about it, in any projects you are going to face the same needs such as defining your calendar, time dimensions, your dimensional hierarchies, your fact tables and aggregation tables. How does BI App actually do it?

Hint: This article gives some helpful hints. To configure for the initial full load, you need to go through several configuration steps in Dac and Informatica. Such as defining initial extract date parameter in DAC to avoid loading way too much record, configure DAC Source system parameters for global currencies, exchange rate types, Nullify the refresh date tab in DAC to enable full load to W_Day_D dimension (based table for all calendars in BI Apps) and define $start_date and $end_date parameter for Task SIL_Daydimension so that DAC will load data into Date dimension based on those date ranges. Run PLP tasks to load aggregate tables, configure GL Account hierarchies, etc

4. If your business is international, you are likely to deal with transactions that are not in just 1 currency, but multiple currencies. How does BI Apps handle this?

Hint: Found above

5. Inevitably, any business is going to want to customize the BI App to make it more specific to their business, how does BI App make it easier for such customization? What are the levels of customization?

Hint: There are category 1 and category 2 customization. For cat 1, it is about bringing in additional fields from the source into target. In all of the pre-built mappings, there is an unmapped field 'x_custom' in pretty much every transformation. Your new field should go through the same sequence and flow as x_custom to ensure it's safe arrival to the target. For Cat 2, it is about bringing new tables and dimensions into the mapping. Use your informatica knowledge to do it against the requirement. The best way and the only way Oracle will support your customization is by creating custom folders in your Informatica and Custom container in DAC, then copy the pre-built mappings/workflows into this folder to make your customization, change DAC task to point to these new folders so that the execution plan will run these workflows instead of the original ones. DON'T EVER CUSTOMIZE DIRECTLY IN ORIGINAL MAPPING.

6. Inevitably, there will be records deleted in the OLTP system later on, how does BI App handle this situation so that the deleted records won't show up in its warehouse?

Hint: Informatica has pre-built mappings that handle deletion to the warehouse records. This article gives a good explanation.

7. In any ETL framework, there is going to be needs for maintaining historical records in the tables. How does BI App handle the loading of SCD? What's BI App's way of checking and flagging records that become history?

Hint: There are a lot of approach to this problem. The bottom-line is, how to identify records that have been updated and once it's been identified, what to do about it? Using orahash value has been a traditional way by a lot of DBAs to identify records that have been changed. When any of the key attributes related to this record has changed (such as address, phone number, name etc related to this specific account changes), new orahash key gets generated. There must be fields that stores information such as record start date, end date and history flag in the dimension where the primary key will be attached to timestamp to ensure uniqueness. Knowing the idea, how does BI App handle it there way (no necessarily using Orahash )? This article can be helpful.


8. How does BI App handle incremental load?

Hint: In a lot of the pre-built mapping, you will notice that it has 2 workflow sessions. The suffix will suggest which one is full load and which is incremental. The DAC Task window will also provide setting for both full load and incremental load sessions as mentioned here.

9. When it comes to data modeling in OBIEE, there are going to be a lot of snowflaking of dimensions? If you are dealing with financial analytic, you will see that a lot of the dimensions are at different granularity that won't join to the fact. Fact tables are aggregated at different levels for optimizing performance, how are these being modeled in the rpd?

Hint: In your OBIEE rpd, you will notice that in the BMM layer, there are lots of logical tables being mapped to multiple LTS. This is creating logical star schema out of highly normalized physical snowflake schema. This is almost like creating a logical view that joins multiple physical tables.

10. Any applications will have to deal with upgrades and migrations. How does that work in BI Apps?

Hint: If your customization is done accordingly, the upgrade should be fairly easy.

11. Security is always a big concern for any software, what are the security models provided by BI Apps?

Hint: This document gives good information

12. Last but not least, having some domain knowledge about the business is always important. If you are dealing with Financial analytics, what does business unit means, what about chart of account, line of business, GL stuffs? What business information do dashboards like Payables, receivables, profitability provide for financial analytics? What about HR Analytics?

Hint: This is something you will gain through experience, research and curiosity. 

These are areas that you have to investigate and research to gain better understanding of how BI Apps work, if you want to excel in interviews. Not only you have to be familiar with the topics, the customization and handling of such a vast application, but also start thinking in terms of what is the nature of the business problems and how BI App solves it. If you can relate BI Apps solutions with data warehouse solutions in general, things will start making more sense, because if you have ever designed and implement any solutions with your own resource before, you will realize that a lot of the problems and concerns have already been addressed in BI Apps. Therefore, the engineering of it becomes minimum, the customization and handling of the operation is what BI App is all about.

Thanks

Until next time

2 comments:

itsmyhyderabad said...

Got to know a very important copncept on ORacle BI
thanks a lot for the Work
OBIEE Success

Zepharia Andres said...

You have to really use your imagination to refresh your daily life. See the link below for more info.

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