1. Explain The difference between a hot backup and a cold backup and the benefits associated with each.
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a hot backup was basically taking A backup of the database while it was still up and running and it must being in Archiv E log mode. A cold backup was taking a backup of the database while it was shut down and does not require being in Archive log mode. The benefit of taking a hot backup was that the database was still available for use while the backup was occurring and you C An recover the. The benefit of taking a cold backup is, it's typically easier to administer the backup and recovery process. In addition, since you is taking cold backups the database does not require being in Archive log mode and thus there would Be a slight performance gain as the database was not cutting archive logs to disk.
2. You are just had to restore from backup and does not has any control files. How would do I go about bringing up this database?
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I would create a text based backup control file, stipulating where on disk all the data files were and then issue T The He recover command with the Using Backup control file clause.
3. How does the switch from an Init.ora file to a spfile?
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Issue The Create SPFile from Pfile command.
4. Explain The difference between a data block, an extent and a segment.
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a data block is the smallest unit of logical storage for A database object. As objects grow they take chunks of additional storage that is composed of contiguous data blocks. These groupings of contiguous data blocks is called extents. All the extents this an object takes when grouped together is considered the segment of the database object.
5. Give Examples of how you might determine the structure of the table DEPT.
Use the
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describe command or use the DBMS_METADATA.GET_DDL package.
6. Where Would you look for errors from the database engine?
In the
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alert log.
7. Compare and contrast TRUNCATE and DELETE for a table.
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Both the Truncate and delete command has the desired outcome of getting rid of all the rows in a table. The difference between the and the Truncate command is a DDL operation and just moves the high water mark and prod UCEs few rollback data. The delete command, on the other hand, is a DML operation, which would produce rollback data and thus take longer to comple Te.
8. Give The reasoning behind using an index.
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Faster access to data blocks in a table.
9. Give The types of tables involved in producing a star schema and the type of data they hold.
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Fact tables and dimension tables. A fact table contains measurements while dimension tables would contain data that would help describe the fact tables.
Ten. What type of index should you to use on a fact table?
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A Bitmap index.
Give Some examples of the types of the database contraints you could find in Oracle and indicate their purpose.
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- A Primary or Unique Key can be used to enforce uniqueness on one or more columns.
- A referential Integrity contraint can be used to enforce a Foreign Key relationship between both tables.
- A not Null constraint-to ensure a value was entered in a column
- A value constraint-to check a column Value against a specific set of values.
a table is classified as A parent table and you want to drop and re-create it. How would does this without affecting the children tables?
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Disable the FOREIGN KEY constraint to the parent, drop the table, re-create the table, enable the foreign key const Raint.
Explain the difference between ARCHIVELOG mode and Noarchivelog mode and the benefits and disadvantages to each.
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ARCHIVELOG mode is a mode so can put the database in for creating a backup of all transactions that has OCCU Rred in the database so, can recover to any of the point in time. Noarchivelog mode is basically the absence of ARCHIVELOG mode and have the disadvantage of not being able to recover to any Point in time. Noarchivelog mode does has the advantage of not has to write transactions to an archive log and thus increases the per Formance of the database slightly.
What command would do I use to create a backup control file?
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Alter Database backup control file to trace.
Give the stages of instance startup to a usable state where normal users may access it.
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startup nomount-instance
startup
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startup Mount-the database is mounted
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startup OP En-the database is opened
What column differentiates the v$ views to the gv$ views and how?
The
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inst_id column which indicates the instance in a RAC environment the information came from.
Would how do I go about generating an EXPLAIN plan?
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Create A plan table with Utlxplan.sql.
Use the
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explain plan set statement_id = ' Tst1 ' to plan_table for a SQL statement
look at the
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Explain plan with utlxplp.sql or Utlxpls.sql
How would do I go about increasing the buffer cache hit ratio?
Use the
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buffer cache advisory over a given workload and then query the V$db_cache_advice table. If a change is necessary then I would use the ALTER system set DB_CACHE_SIZE command.
Explain an ORA-01555.
You
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get the snapshot too old within rollback. It can usually is solved by increasing the undo retention or increasing the size of rollbacks. You should also look at the logic involved in the application getting the error message.
Explain the difference between $ORACLE _home and $ORACLE _base.
Oracle_base is the
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root directory for ORACLE. Oracle_home located beneath Oracle_base is where the ORACLE products reside.
From Http://www.orafaq.com/wiki/Interview_Questions
Oracle Interview-1
