Which of the forlowing statements is incorrect? (A) A view in SQL terminology is a single table that is derived from other base tables or previously defined views. (B) A view is supposed to be always up-to-date; if we modify the tuples in the base tables on which the view is defined, the view must automatically reflect these changes. (C) A view is usally realized or materialized at the time of view definition. (D) Views defined on multiple tables using joins are generally not updatable. (5) Which of the following statements is incorrect. (A) Double buffering permits continuous reading or writing of data on consecutive disk blocks, which can eliminate the rotational delay and block transfer time. (B) A file may have variable-length records due to variable-length fields, repeating field, optional field, or mixed file. (C) The types of file organization in database can be heap file, sequenial file, hashing file, and indexed file. (D) Modifying a field value in a record of an ordered file would depend on two factors: (1) the search condition to locate the record, and (2) the field to be modified. (6) Which of the following statements is incorrect? (A) Static hashing can cause a serious drawback for dynamic files because it can result in a lot of unused disk space or numerious collisions. (B) Linear hashing allows a hash file to expand and shrink its number of buckets dynamically without needing a directory. (C) Extensible hashing needs to maintain a list of overflow buckets for resolving collisions. (D) In linear hashing, we can use file load to trigger both bucket splits and combinations so that the file load can be kept within a desired range. (7) Which of the following statements is incorrect? (A) Different RAID organizations were defined based on the different combinations of two factors: (1) granularity of data interleaving and (2) pattern used to compute redundant information. (B) The mirroring technique is used to improve performance of disks in RAID. (C) In RAID, the disk striping can be applied in different granularity: bitlevel or block-level data striping. (D) None of the above. (8) Which of the following statements is incorrect? (A) Both primary and clustering indexes are nondense. (B) A secondary index can be either dense or nondense. (C) The scheme of multilevel index can be used on any type of index, including primary, clustering, or secondary index. (D) None of the above. (9) Which of the following statements is incorrect? (A) A data file can have either a primary index or a clustering index. (B) A data file can have several secondary indexes in addion to to its primary index. (C) A secondary index can only be created on a field that is nonkey with duplicated values. (D) A clustering index is created on a nonkey; ordering field of a file. (10) We want to use the linear hashing scheme for a disk file with M buckets numbered 0,1,,M1. The hash function is h(K)=KmodM. Suppose initially a collision leads to an overflow record on bucket 0 and the bucket 0 is splitted into two buckets 0 and M. Suppose that the next collision happens in bucket N, where 1
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