Chapter 2 [ 35 ] Study carefully how the MYR 2009 number can be easily added to the MYR 2010 number to give us the Total Model Year number. This is a highly simplied example of an Essbase database outline, its structure, and relationships. In the next chapter, we will go over the Essbase database outline much more thoroughly. In the next section, we shall use what we have learned here to make decisions on the best methods to store data in our Essbase database. Determine data storage options Get ready to toss out everything you've ever learned about storing data in a typical relational database with tables, rows, and columns. Keeping the above example of the Essbase outline in mind, we will now begin covering how the data is stored in Essbase and the various options available to you (the Essbase programmer). An Essbase cube usually stores less physical data than a typical relational database must store to deliver the same results to the user. Usually, the greatest saving is in the expense of data retrieval times. The results returned from a typical Essbase database require less processing overhead than the similar results being delivered as the result of queries performed against relational database tables. Essbase stores data in what is commonly referred to as a multidimensional array. This material is copyright and is licensed for the sole use by Paul Corcorran on 5th July 2009 8601 ave. p #1, , lubbock, , 79423 Download at Boykma.Com Essbase Data and Design Considerations [ 36 ] Inside the multidimensional array are the data cells. It is these data cells where the data is actually stored. The smallest vehicle that Essbase uses to store data is a cell. A data cell however, cannot stand alone. The smallest usable vehicle to store data, contained in an Essbase database, is the data block (see the following gure). These data blocks are the building blocks of the Essbase cube: Scenario 1 Scenario 2 Production Sales Stock Profit Jan Feb Mar Apr A simplied explanation is that the data blocks are made up of data cells. The number of data cells are, for the most part, in direct relation to the number of dimensions in the Essbase outline (the data attributes explained previously), and the number of possible data combinations or intersections that can be created. Relational Sales Table Country Country Vehicle Vehicle Model Year Retail Retail Fleet Fleet Total Total US US US US Sedan Sedan 4-Door 4-Door 2010 2010 2010 2010 50 33 200 67 250 100 Relational Stock Table 7575 45 155 150 200 Model Year In a traditional relational database, one new element of data may require an entire new row of data in one to many tables. Looking at the previous screenshot, you can see that if you need to add stock information on a vehicle, you will need to insert a new row in the Stock table of your relational database. In Essbase, that same new piece of data is plugged into the waiting data cell that was created in the data block, when the database outline was structured or restructured. You can add a new dimension to the database outline or add new members to an This material is copyright and is licensed for the sole use by Paul Corcorran on 5th July 2009 8601 ave. p #1, , lubbock, , 79423 Download at Boykma.Com Chapter 2 [ 37 ] existing dimension at any time. By adding dimensions to the database outline, you are actually increasing the size of the data block. When a data block is created by Essbase, it contains cells for all of the various dimensions whether you have the data at that point or not. In our example, the data block created by the database would already contain a cell for stock, even if you did not yet have a value to store there. When you have a value for stock, it just gets plugged into its data cell and the size of the database is unaffected. When you add or remove information from the outline and save the outline, Essbase will automatically restructure the database and modify the data blocks (add/remove data cells) to incorporate the new outline information as necessary. In Oracle Essbase there are two distinct storage options that can be used when creating a database. These storage options are known as the Block Storage Option (BSO) and the Aggregate Storage Option (ASO). These storage options are discussed in greater detail later in this book. For most transactional Essbase applications, the more suitable of the two options is the BSO. For our example in this book, we will create an Application|Database using the BSO. It should be mentioned that the size of the data blocks can have a dramatic effect on the performance of the system. It is always best to try and avoid extremely large and complex database outlines. As we explained previously, the data blocks are structured roughly in relation to the possible combinations of data based on the number of members in the database outline. More members = larger data blocks. Less members = smaller data blocks. Oracle Essbase offers an extremely valuable option to help keep block sizes to a minimum in order to help keep your database running at peak performance. The dynamically calculated database member! This material is copyright and is licensed for the sole use by Paul Corcorran on 5th July 2009 8601 ave. p #1, , lubbock, , 79423 Download at Boykma.Com Essbase Data and Design Considerations [ 38 ] The dynamically calculated member is a measure typically derived from other data elements in the database. It is not physically stored in the database. Instead, it is only created (calculated) at the time you ask for it. There are three great benets for building your database with dynamically calculated members: 1. There is a huge potential to create many new measures without adding new sources of data or writing expensive programs to derive the values. 2. While the dynamically calculated member occupies a place in the database outline, it does not affect the block size in the database, therefore, it does not affect performance. 3. The resultant measure is always accurate to the other measures in the database and will always tally (the derived number will always equal the result of the stored component numbers). There is never a question of "where did this number come from?". Types of Essbase applications A nice feature of Oracle Essbase is that it allows you to create high level umbrella applications under which you can group similar databases. The similarity in databases means they are either similar in function or purpose. When we speak of an Essbase application, it must be noted that all databases are created under an umbrella application. You may have one or many databases under an application, but you cannot create a database without a parent application. Likewise, an application is virtually useless without dependent databases. Oracle recommends that we have only one database for an application. The reason for this is that when you restructure a database, the entire application is locked and you will not be able to perform any other actions on the application or dependent databases. This Application|Database structure allows for a more organized layout and design and also allows for better data and security management. As mentioned, an Essbase application can be one of two types: 1. Aggregate Storage Option 2. Block Storage Option Let's discuss them in detail. This material is copyright and is licensed for the sole use by Paul Corcorran on 5th July 2009 8601 ave. p #1, , lubbock, , 79423 Download at Boykma.Com Chapter 2 [ 39 ] Aggregate Storage Option (ASO) In Essbase 9.x versions, the ASO is also called Essbase analytics. The ASO is most suitable for the sparser data sets of high dimensionality, allowing a greater number of dimensions and members. The ASO model is not a replacement for the BSO, but it is an alternative for the business users depending on the needs of the customer. In an Essbase Application|Database built using ASO, the data is loaded into the leaf nodes or lowest levels, but are not aggregated into the upper levels using typical Essbase calc and store methods. Rather, they are calculated dynamically on the y (per user request). It must also be mentioned that the ASO is best suited as a Read Only application. It is best used when analysis on large amounts of data is necessary for presentation, analysis, or reporting purposes. We will talk more about ASO, and the differences between ASO and BSO, in Chapter 10. This material is copyright and is licensed for the sole use by Paul Corcorran on 5th July 2009 8601 ave. p #1, , lubbock, , 79423 Download at Boykma.Com . Corcorran on 5th July 20 09 8601 ave. p #1, , lubbock, , 794 23 Download at Boykma.Com Chapter 2 [ 39 ] Aggregate Storage Option (ASO) In Essbase 9. x versions, the ASO is also called Essbase analytics above example of the Essbase outline in mind, we will now begin covering how the data is stored in Essbase and the various options available to you (the Essbase programmer). An Essbase cube usually. outline, Essbase will automatically restructure the database and modify the data blocks (add/remove data cells) to incorporate the new outline information as necessary. In Oracle Essbase there