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GeekInterview.com > Interview Questions > Oracle > System Architecture
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Question: What do Database Buffers contain ?
Answer: Database buffers store the most recently used blocks of database data. It can also contain modified data that has not yet been permanently written to disk. |
| July 07, 2009 03:10:37 |
#4 |
| saihaan |
Member Since: March 2009 Total Comments: 2 |
RE: What do Database Buffers contain ?
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Database buffers consists of the dirty blocks. When ever we are trying to update some table/etc. First it verifies whether the data exists in database buffer , If not it fetches the information from data files to database buffer. So the modified values exists in db buffer until a check point
occurrence. When the transaction is committed then the dirty blocks/modified blocks will be written on to the data files with the help of a db writer. If the transaction is not committed/rolled back then the data from the undo segment will be moved to data files.What ever
SQL statement that is executed, it checks in db buffer before retrieving the data from data files. |
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