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ORACLE Interview Questions and Answers
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(Continued from previous part...)
811. What is the use of break group?
What are the various sub events a mouse double click event involves?
A break group is used to display one record for one group ones. While multiple related records in other group can be displayed.
812. What tuning indicators can one use? (for DBA
The following high-level tuning indicators can be used to establish if a database is performing optimally or not:
. Buffer Cache Hit Ratio
Formula: Hit Ratio = (Logical Reads - Physical Reads) / Logical Reads
Action: Increase DB_CACHE_SIZE (DB_BLOCK_BUFFERS prior to 9i) to increase hit ratio
. Library Cache Hit Ratio
Action: Increase the SHARED_POOL_SIZE to increase hit ratio
813. What tools/utilities does Oracle provide to assist with performance tuning? (for DBA
Oracle provide the following tools/ utilities to assist with performance monitoring and tuning:
. TKProf
. UTLBSTAT.SQL and UTLESTAT.SQL - Begin and end stats monitoring
. Statspack
. Oracle Enterprise Manager - Tuning Pack
814. What is STATSPACK and how does one use it? (for DBA
Statspack is a set of performance monitoring and reporting utilities provided by Oracle from Oracle8i and above. Statspack provides improved BSTAT/ESTAT functionality, though the old BSTAT/ESTAT scripts are still available. For more information about STATSPACK, read the documentation in file $ORACLE_HOME/rdbms/admin/spdoc.txt.
Install Statspack:
cd $ORACLE_HOME/rdbms/admin
sqlplus "/ as sysdba" @spdrop.sql -- Install Statspack -
sqlplus "/ as sysdba" @spcreate.sql-- Enter tablespace names when prompted
Use Statspack:
sqlplus perfstat/perfstat
exec statspack.snap; -- Take a performance snapshots
exec statspack.snap;
o Get a list of snapshots
select SNAP_ID, SNAP_TIME from STATS$SNAPSHOT;
@spreport.sql -- Enter two snapshot id's for difference report
Other Statspack Scripts:
. sppurge.sql - Purge a range of Snapshot Id's between the specified begin and end Snap Id's
. spauto.sql - Schedule a dbms_job to automate the collection of STATPACK statistics
. spcreate.sql - Installs the STATSPACK user, tables and package on a database (Run as SYS).
. spdrop.sql - Deinstall STATSPACK from database (Run as SYS)
. sppurge.sql - Delete a range of Snapshot Id's from the database
. spreport.sql - Report on differences between values recorded in two snapshots
. sptrunc.sql - Truncates all data in Statspack tables
815. What are the common RMAN errors (with solutions)? (for DBA
Some of the common RMAN errors are:
RMAN-20242: Specification does not match any archivelog in the recovery catalog.
Add to RMAN script: sql 'alter system archive log current';
RMAN-06089: archived log xyz not found or out of sync with catalog
Execute from RMAN: change archivelog all validate;
816. How can you execute the user defined triggers in forms 3.0 ?
Execute Trigger (trigger-name)
817. What ERASE package procedure does ?
Erase removes an indicated global variable.
818. What is the difference between NAME_IN and COPY ?
Copy is package procedure and writes values into a field.
Name in is a package function and returns the contents of the variable to which you apply.
819. What package procedure is used for calling another form ?
Call (E.g. Call(formname)
820. When the form is running in DEBUG mode, If you want to examine the values of global variables and other form variables, What package procedure command you would use in your trigger text ?
Break.
SYSTEM VARIABLES
821. The value recorded in system.last_record variable is of type
a. Number
b. Boolean
c. Character. ?
b. Boolean.
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