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ORACLE Interview Questions and Answers
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(Continued from previous part...)
333. What is cold backup? What are the elements of it?
Cold backup is taking backup of all physical files after normal shutdown of database. We need to take.
- All Data files.
- All Control files.
- All on-line redo log files.
- The init.ora file (Optional)
334. What is meant by redo log buffer ?
Changes made to entries are written to the on-line redo log files. So that they can be used in roll forward operations during database recoveries. Before writing them into the redo log files, they will first brought to redo log buffers in SGA and LGWR will write into files frequently. LOG_BUFFER parameter will decide the size.
335. How will you estimate the space required by a non-clustered tables?
Calculate the total header size
Calculate the available dataspace per data block
Calculate the combined column lengths of the average row
Calculate the total average row size.
Calculate the average number rows that can fit in a block
Calculate the number of blocks and bytes required for the table.
After arriving the calculation, add 10 % additional space to calculate the initial extent size for a working table.
336. How will you monitor the space allocation ?
By querying DBA_SEGMENT table/view.
337. What is meant by free extent ?
A free extent is a collection of continuous free blocks in tablespace. When a segment is dropped its extents are reallocated and are marked as free.
338. What is the use of IGNORE option in IMP command ?
A flag to indicate whether the import should ignore errors encounter when issuing CREATE commands.
339. What is the use of ANALYSE ( Ver 7) option in EXP command ?
A flag to indicate whether statistical information about the exported objects should be written to export dump file.
340. What is the use of ROWS option in IMP command ?
A flag to indicate whether rows should be imported. If this is set to 'N' then only DDL for database objects will be executed.
341. What is the use of INDEXES option in EXP command ?
A flag to indicate whether indexes on tables will be exported.
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