mis 406 ch.11 questions

8. What is the biggest strength of the object database? Describe two of its weaknesses.

- based on object orientation: things be treated as objects that have both data and processes -mainly used to support multimedia applications or systems that involve complex data

10. What are the two most important factors in determining the type of data storage format that should be adopted for a system? Why are these factors so important?

- data types - type of application system - existing storage formats - future needs pg. 355 - storage formats

19. Describe several techniques that can improve performance of a database.

- denormalization (add back redundancy, reduces number of joins) - clustering (combining sets of data together to achieve faster speeds) - indexing - estimating the size of data for hardware planning

18. Describe three situations that can be good candidates for denormalization.

- denormalization can be good for look-up tables , which are tables that contain descriptions of values (a table of product descriptions, a table of payment types). -1:1 relationships are good candidates for denormalization. Although logically, two entities should be separated, from a practical standpoint the information from both entities may be regularly accessed together (better to find two related values, finding order detail from shipping mode, quantity, etc.)

What are the key issues in deciding between using perfectly normalized databases and denormalized databases?

-Preferable to use normalized files. THese are more directly mapped to problemdomain entities, are less redundant, and more maintainable. - -Denormalizing databases can improve performance when updating changes are infrequent or not needed

3. What is the difference between an end-user database and an enterprise database? Provide an example of each one.

An end-user DBMS is signifi cantly less expensive and easier for novice users to use than its enterprise counterpart, but it does not have the features or capabilities that are necessary to support mission-critical or large-scale systems

22. Describe what should be considered when estimating the size of a database.

apply volumetrics - technique of estimating the amount of data that the hardware must support -calculate the amount of raw data (all data stored within database tables) -calculate overhead requirements based on database vendors recommendations -record number of initial records loaded into the table, and expected growth

4. Name fi ve types of fi les, and describe the primary purpose of each type.

data file - electronic lists of data, optimized to perform a particular transaction, master file - store core information important to the application look-up files - contain static values (files that database refers to to make sure its legitimate, valid zipcodes, countries, etc.), sometimes need to be updated transaction files - store information that can be used to update a master file (modifies data, makes a specific change to a specific record, change amazon order, etc.) audit files - record "before" and "after" images of data as data is altered (logs and tracks certain information, see at which point what person of 30 broke login info) history files (or archive files) - store past transactions

7. What is referential integrity, and how is it implemented in a relational database?

ensures that values linking the tables together are valid and correctly synchronized

2. How are a fi le and a database diff erent from each other?

files are singular, electronic lists of data, optimized to perform a particular transaction, databases are a whole packed data storage, collection of groupings of information that are related to each other in some way

1. Describe the two steps to data storage design

functionality and design

21. What is an index, and how can it improve the performance of a system?

index - similar to a book index, containing values from one or more columns in a table and the location of the values within the table makes efficiency speed a lot better can index to see how much customer spend on your business have a real scope on business intelligence

20. What is the diff erence between interfi le and intrafi le clustering? Why are they used?

interfile - combining records from more that one table

23. Why is it important to understand the initial and projected size of a database during the design phase?

so that the system will perform to the highest efficiency and be able to handle the amount of data inputted in.

5. Name five types of legacy databases and the main problems associated with each type.

legacy database: based on older tech. seldom used to develop new applications hierarchical databases - use hierarchies, or inverted trees, to represent relationships network databases - collections of records that are related to each other through pointers problem: companies do not want to optimize for efficiency because everything is cheap now (would just buy new hard drives instead to optimizing by hand)

12. What are the diff erences between the logical and physical ERDS?

logical - business view of data, no implementation (sends request to view data, dont know details of file) physical - show implementation details, explain to show "how" of the final system, whats behind it (physical includes entities, relationships, and attributes)

6. What is the most popular kind of database today? Provide three examples of products that are based on this technology.

relational database: based on collection of tables, primary key and foreign key related - SQL based on relational database

17. What is the purpose of normalization?

removing redundancy; very few null values best way to achieve efficiency

9. How does the multidimensional database store data?

through data warehousing and data marts data warehousing - taking and storing data that supports business intelligence systems data mart - smaller databases based on data warehouse data; support BI pointers and index hexing, referring to key Stores data to support aggregations of data on multiple dimensions. When the data are first loaded into a multidimensional database, the database precalculates the data across the multiple dimensions and stores the answers for fast access.