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Database Essentials
Administrative Planning : Data layout

Data layout

Proper database design is essential because all data originates from a storage area. Consider the following important facts:
*A database is made up of storage areas.
*Each storage area can contain one or more objects.
*A database object is a table or an index or LOB.
*There are other objects, such as sequences and schema. Currently, OpenEdge controls the locations of these objects.
*Each storage area can contain one or more extents or volumes on disk.
*The extents are the physical files stored at the operating system level.
*Each extent is made up of blocks, and you can determine the block size for your database. The block sizes that you can choose from are: 1KB, 2KB, 4KB, and 8KB.
*You can have only one block size per database, but each area can have differing numbers of records per block.
There are several things to consider when determining the layout of a database. The first is your mean record size. This is easy to learn if you have an existing OpenEdge database, because this information is included in the output of running the database analysis utility. Other information you must consider is specific to your application and answers the following questions:
*Is the table mostly accessed sequentially or randomly?
*Is the table frequently used, or is it historical and thus used infrequently?
*Do the users access the table throughout the day, or only for reporting?
*Do individual records grow once they are inserted, or are they mostly static in size?
The answers to these questions help determine the size and layout of a database.
* Calculating database storage requirements
* Sizing your database areas