C reusing as much generic code as possible d

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Unformatted text preview: eplacing bind variables with constants. C. Reusing as much generic code as possible. D. Replacing database constraints with triggers. Actualtests.com - The Power of Knowing 1Z0-024 Answer: C Explanation: To improve the performance of the library cache you need use as much generic code as possible, so it will not be reloaded and re-parsed for new SQL statements. Incorrect Answers: A: More frequent COMMIT statements will not improve the performance of the library cache. B: Replacing bind variables with constants can improve the performance of the library cache, but not in all cases. D: Replacing database constraints with triggers have nothing to do with the library cache performance. Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 853-854. Chapter 18: Tuning Memory and Operating System Use QUESTION 56: The cost-based optimizer can choose between a nested loops join and a sort merge join operation. All tables are analyzed and the OPTIMIZER_MODE is set to FIRST_ROWS. Which execution plan will be the result? A. The sort-merge join. B. The nested loops join. C. This depends on some sort parameter values. D. This depends on the number of rows in each table. Answer: B Explanation: If OPTIMIZER_MODE is set to FIRST_ROWS and all tables are analyzed, cost-based optimizer will choose the nested loops join, not a sort-merge join operation for the execution plan. The FIRST_ROWS goal optimizes Oracle to give the best response time for online applications, such as Oracle Forms, other GUI tools, or SQL*Plus queries where users are waiting to see some data, but don't necessarily need the best overall time for returning all rows of output from the query. With this setting, the RDBMS will prefer to use full table scans and nested loop join operations in the execution plan. Incorrect Answers: A: The nested loops join will be selected, not the sort-merge join operation. C: Oracle optimizer will choose the nested loops join regardless other sort parameter values. D: Oracle optimizer will choose the nested loops join regardl...
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This document was uploaded on 03/08/2014.

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