Elm04_U - not to add one to the number of distinct values for a given column The database administrator would execute a DBMS utility to gather the

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Chapter 17: Database System Architectures and the System Catalog Answers to Selected Exercises 17.10 No solution provided. 17.11 Solution pending. 17.12 No solution provided. 17.13 Solution pending. 17.14 Solution pending. 17.15 Why are database statistics such as those stored in Oracle, not updated automatically after every insert/delete/update to a table? Updating the statistics constantly may require too much overhead. Just consider the column statistic that indicates the number of distinct values for a given column. For example, on an insert, it may require a complete table scan to decide whether or
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Unformatted text preview: not to add one to the number of distinct values for a given column. The database administrator would execute a DBMS utility to gather the current statistics about the database periodically. This is a reasonable approach since the statistics will probably not change too much in a short time. Also, the query optimizer should be able to tolerate some amount of inacurracy in the statistics when searching for the "best" query plan. Pre-Publication Material: This is draft manuscript yet to be copy edited or paged. Copyright AWL2003 81...
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This note was uploaded on 09/19/2011 for the course CS 324 taught by Professor Mohammedhajali during the Spring '10 term at Amity University.

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