Replicated databases create considerable data redundancy, which is in conflict with the database concept. Explain the justification of this approach.
What will be an ideal response?
The primary justification for a replicated database is to support read-only queries in situations involving a high degree of data sharing, but no primary user exists. With data replicated at every site, data access for query purposes is ensured, and lockouts and delays due to network traffic are minimized. A potential problem arises, however, when replicated databases need to be updated by transactions. Since each site processes only local transactions, the common data attributes that are replicated at each site will be updated by different transactions and thus, at any point in time, will have uniquely different values. System designers need to employ currency control techniques to ensure that transactions processed at different locations are accurately reflected in all the databases copies.
PTS: 1
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Discuss some cautions about software RAID.
What will be an ideal response?
The __________ command is used to track the revisions in a document.
Fill in the blank(s) with the appropriate word(s).
When you create a ____ report, the records must have been sorted in order by a key field.
A. summary B. control break C. detail D. totals
Answer the following statements true (T) or false (F)
1. The conditional test is made at the end of the REPEAT/UNTIL instruction. 2. When using a WHILE/WHILE-END instruction, if the condition is false before entering the loop, the loop instructions will still be processed one time. 3. When using a REPEAT/UNTIL instruction, if the condition is false before entering the loop, the loop instructions will still be processed at least one time. 4. Automatic counter loops should be used only when you do not know how many times the loop should be executed. 5. All loop structures use the diamond in the flowchart to indicate a loop.