1. The following will identify the level (user, programmer of application software, and designer of the DBMS software) within a database system at which each of the following concerns or activities occurs:
a. How data should be stored on a disk to maximize efficiency occurs on the level of the designer of the DBMS software (Brookshear, 2012).
b. Whether or not there is a vacancy on flight 243 would be stored on the level of the user (Brookshear, 2012).
c. The possibility of a relation being stored as a sequential file would occur on the level of the designer of the DBMS software (Brookshear, 2012).
d. The amount of times a user should be allowed to mistype their password before the communication is terminated would occur on the level of the programmer of application software (Brookshear, 2012).
e. How the project operation would be implemented would be stored on the level of the programmer of application software (Brookshear, 2012).
2. Supposing a sequential file contains 50,000 records, and 5 milliseconds are required to interrogate an entry, we should expect to wait 2.08 minutes when retrieving a record from the middle of the file (LET Conversion, 2014). (50000/2=2500085=125000ms=125s=2.08min)
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3. One advantage that:
a. a sequential file has over an indexed file is that the sequential file may be stored in sequence, making it easy to “read” straight through from one end to the other; nothing is out of order (Brookshear, 2012).
b. a sequential file has over a hash file is that it is stored in logical order, not dispersed in any way (Brookshear, 2012).
c. an indexed file has over a sequential file is the ability to store data out of sequence (Brookshear, 2012).
d. an indexed file has over a hash file is that it offers a clear path to the location of the file, not needing a key value to locate pertinent information (Brookshear, 2012).
e. a hash file has over a sequential file is that information may be located quickly from within a data storage system (Brookshear, 2012).
f. a hash file has over an indexed file is that the key value offers a direct location for a record via utilization of the key value instead of reading the location off of an index and then having to search for that location (Brookshear, 2012).
- Brookshear, J. G. 2012. Computer science. 11th ed. Boston: Pearson/Addison Wesley.
- LET Conversion. 2014. Milliseconds to Seconds Conversion Calculator – LetConversion. [online] Available at: http://letconversion.com/time-conversion/from-milliseconds/to-seconds [Accessed: 5 Feb 2014].
