Tablespace containing a rollback segment d different

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Unformatted text preview: e same disk C. Tablespace containing a rollback segment D. Different tablespaces on different disks Answer: D Explanation: For better performance the ORDERS table and the ORDID_NDX index must be stored in different tablespaces on different disks. Incorrect Answers: A: If these objects will be in the same tablespace it will cause performance degradation. B: Different tablespaces on the same disk will still require extensive I/O operations contention, because Oracle will try to retrieve index and data blocks from one disk device in one time. C: It's not recommended to put data or index tablespaces on disk, where rollback segments are located: it will cause I/O contention. Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 844. Chapter 18: Tuning Memory and Operating System Use QUESTION 36: Which two statements about row migration are true? (Choose two) A. Row migration is caused by a PCTREE value set too low. B. Row migration can be resolved using the ANALYZE command. C. Row migration can be reduced by choosing a larger block size. D. Row migration means that row pieces are stored in different blocks. E. Queries that use an index to select migrated rows perform additional I/O Answer: A, B Explanation: Higher PCTFREE values represent a proactive solution to row chaining and migration. The ANALYZE OBJECT_NAME LOST CHAINED ROWS INTO CHAINED_ROWS command is used to determine whether there are chained rows in the database. Incorrect Answers: C: Row migration cannot be reduced by choosing a larger block size, because it's impossible to predict size for all updates for rows. D: Row migration occurs when a user process updates a row in an already crowded data block, forcing Oracle to move the row out of that block and into another one that can accommodate the row. Row chaining means that row pieces are stored in different locks. It happens when Oracle attempts to migrate the row but cannot find a block large enough to fit the entire row, so it breaks the row into two ore more parts and stores par...
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