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28 Cards in this Set
- Front
- Back
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Name 3 main physical structures
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-datafiles
-redo log files -control files |
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Name 5 main logical structures, in order from largest to smallest
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1. tablespace
2. schema object 3. segment 4. extent 5. data block |
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How many segments does a non-partitioned schema object hold?
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one
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Name seven kids of schema objects
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-tables
-indexes -views -procedures -Java-stored procedures -object tables -sequences |
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What is an extent?
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a contiguous group of data blocks that are assigned to a segment
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Can an extent belong to multiple segments?
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No
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Can a segment hold multiple extents?
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Yes
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Can a database block belong to multiple extents?
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No
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Can an extent hold multiple data blocks?
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Yes
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What determines the name of a segment?
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It is the same as the name of its parent schema object
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How are extents named?
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They do not have specific names.
They are numbered sequentially starting at zero for each segment |
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How are blocks named?
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They do not have specific names.
They are numbered sequentially starting at zero, relative to their position in the datafile. |
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What component is the intersection of the logical and physical structures?
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Data blocks. They exist within extents in the logical structure, and within datafiles in the physical structure.
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How are segments and datafiles related?
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There is no direct correlation. A segment can be spread among several datafiles as long as the datafiles belong to the segment's tablespace.
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What are data blocks made of?
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One or more operating system blocks, depending upon the size of each type of block.
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What is the physical difference between locally-managed and dictionary-managed tablespaces?
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Locally-managed tablespaces have a bitmap in their header containing info about free space, used space and location of extents. Dictionary-managed tablespaces maintain this data in the data dictionary tables.
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What is the minimum extent size the system can set?
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64Kb
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What is the minimum extent size for uniform extents?
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1Mb
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What happens if you haven't created any temporary tablespaces?
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The SYSTEM tablespace is used to store temporary segments, which can degrade performance.
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Should transactional data have large or small data block sizes?
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large
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Should static data have large or small data block sizes?
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small
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What three methods can be used to take a tablespace offline, and how do they affect data and recovery?
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-NORMAL: performs a checkpoint on each datafile. No recovery is needed.
-TEMPORARY: performs a checkpoint on all AVAILABLE datafiles. Recovery will be needed for the bad datafile. -IMMEDIATE: no checkpoint attempted. Media recovery will be required... using backup, archives and redo logs. |
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What are the two most useful data dictionary views of storage data?
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DBA_TEMP_FILES
DBA_DATA_FILES |
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Explain coalescing
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Free extents can be coalesced (brought together into one) when they are adjacent to one another.
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What are the uses of undo data?
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-"redoes" the original data if the user issues a ROLLBACK command.
-provides read consistency for users accessing the table during a pending update -in db recovery, if redo log entries change data that had not been officially committed, the undo data is applied to replace the changed data with the original data |
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What is contained in the bdump directory?
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background process trace files and the alert log
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What is contained in the cdump directory?
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memory state core dump trace files at the time of a database crash
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What is contained in the udump directory?
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trace files of user sessions/connections to the db
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