READ Free Dumps For Oracle- 1z0-023
| Question ID 8791 | What happens to the block when the PCTUSED threshold is crossed?
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| Option A | It is entered into the free list of table.
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| Option B | It is inaccessible to INSERT statements.
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| Option C | It is deleted from the free list of the table.
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| Option D | It is inaccessible to DELETE statements.
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| Option E | It is inaccessible to UPDATE statements.
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| Correct Answer | A |
Explanation Explanation/Reference: Explanation: Answer A is correct. If the PCTUSED threshold is crossed the block will be entered into the free list of table. The PCTUSED option specifies the threshold by which Oracle will determine if it is acceptable to add new rows to a block. A freelist is a list of data blocks that are currently accepting new data rows. Incorrect Answers: B: You can insert into this block when the PCTUSED threshold is crossed. C: It will be inserted into the free list, not deleted from it. D: You still can delete data from this block when the PCTUSED threshold is crossed. E: You can update data from this block when the PCTUSED threshold is crossed. Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 471 Chapter 10: Managing Database Use
| Question ID 8792 | The extent sizes of a table should be _____ to improve performance of the table scans.
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| Option A | All equal
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| Option B | No larger than five times DB_BLOCK_SIZE
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| Option C | Equal to the size of the biggest possible row
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| Option D | A multiple DB_FILE_MULTIBLOCK_READ_COUNT
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| Correct Answer | D |
Explanation Explanation/Reference: Explanation: Answer D is correct. The extent sizes of a table should be multiple DB_FILE_MULTIBLOCK_READ_COUNT parameter in initSID.ora file to improve performance of the table scans. Incorrect Answers: A: The equal extent sizes will not improve performance of the table scans, because for full scans you need to try keep data in less extents as possible. B: Each extent contains at least 5 data blocks, so if you will use no larger than 5 times DB_BLOCK_SIZE it will be minimal possible size of extent. To store data you will need a lot of extents in this case, it will decrease table scans performance. C: If you will determine extent equal to the size of the biggest possible row, you will just waste space, because other rows will use not all space in each extent. Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 348-350 Chapter 7: Managing the Physical Database Structure