Below are some important Memory Management interview questions which are asked in most MNC company interviews for beginners or professionals.
21. It is possible to use raw devices as data files and what are the advantages over file system files?
Yes.
The advantages over file system files.
I/O will be improved because Oracle is bye-passing the kernnel which writing into disk.
Disk Corruption will be very less.
22. What is a Control file?
The Control File is a small binary file necessary for the database to start and operate successfully. Each Control file is associated with only one Oracle database. Before a database is opened, the control file is read to determine if the database is in a valid state to USE.
The Control file is not accessible, the database does not function properly.
23. How will you monitor rollback segment status?
By using dictionaray view's called v$rollstat,dba_rollback_segs.
24. How will you monitor the space allocation?
This can be monitored in DB_data_files.
25. Why query fails sometimes?
Due to syntax errors.
26. How the space utilization takes place within rollback segments?
By correctly fixing optimal size.
27. How will you create multiple rollback segments in a database?
create rollback segment roll1tablespace roll1.
28. What is a rollback segment entry?
When ever changes happend to the database previous change will be there in the rollback segment.
29. What is hit ratio?
Hit Ratio is the ratio of shared SQL and PL/SQL items found in the Library Cache versus physical storage.It can also be defined in a mathematical expression as 1 - ((physical reads) / (db block gets + consistent reads)).
30. What are disadvantages of having raw devices?
We should depend on export/import utility for backup/recovery (fully reliable) The tar command cannot be used for physical file backup, instead we can use dd command which is less flexible and has limited recoveries.
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21. It is possible to use raw devices as data files and what are the advantages over file system files?
Yes.
The advantages over file system files.
I/O will be improved because Oracle is bye-passing the kernnel which writing into disk.
Disk Corruption will be very less.
22. What is a Control file?
The Control File is a small binary file necessary for the database to start and operate successfully. Each Control file is associated with only one Oracle database. Before a database is opened, the control file is read to determine if the database is in a valid state to USE.
The Control file is not accessible, the database does not function properly.
23. How will you monitor rollback segment status?
By using dictionaray view's called v$rollstat,dba_rollback_segs.
24. How will you monitor the space allocation?
This can be monitored in DB_data_files.
25. Why query fails sometimes?
Due to syntax errors.
26. How the space utilization takes place within rollback segments?
By correctly fixing optimal size.
27. How will you create multiple rollback segments in a database?
create rollback segment roll1tablespace roll1.
28. What is a rollback segment entry?
When ever changes happend to the database previous change will be there in the rollback segment.
29. What is hit ratio?
Hit Ratio is the ratio of shared SQL and PL/SQL items found in the Library Cache versus physical storage.It can also be defined in a mathematical expression as 1 - ((physical reads) / (db block gets + consistent reads)).
30. What are disadvantages of having raw devices?
We should depend on export/import utility for backup/recovery (fully reliable) The tar command cannot be used for physical file backup, instead we can use dd command which is less flexible and has limited recoveries.
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