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ORACLE Interview Questions and Answers
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236. What third party tools can be used with Oracle EBU/ RMAN? (for DBA
The following Media Management Software Vendors have integrated their media management software packages with Oracle Recovery Manager and Oracle7 Enterprise Backup Utility. The Media Management Vendors will provide first line technical support for the integrated backup/recover solutions.
Veritas NetBackup
EMC Data Manager (EDM)
HP OMNIBack II
IBM's Tivoli Storage Manager - formerly ADSM
Legato Networker
ManageIT Backup and Recovery
Sterling Software's SAMS:Alexandria - formerly from Spectralogic
Sun Solstice Backup
237. Why and when should one tune? (for DBA
One of the biggest responsibilities of a DBA is to ensure that the Oracle database is tuned properly. The Oracle RDBMS is highly tunable and allows the database to be monitored and adjusted to increase its performance.
One should do performance tuning for the following reasons:
The speed of computing might be wasting valuable human time (users waiting for response);
Enable your system to keep-up with the speed business is conducted; and
Optimize hardware usage to save money (companies are spending millions on hardware).
Although this FAQ is not overly concerned with hardware issues, one needs to remember than you cannot tune a Buick into a Ferrari.
238. How can a break order be created on a column in an existing group?
What are the various sub events a mouse double click event involves?
By dragging the column outside the group.
239. What is the use of place holder column?
What are the various sub events a mouse double click event involves?
A placeholder column is used to hold calculated values at a specified place rather than allowing is to appear in the actual row where it has to appear.
240. What is the use of hidden column?
What are the various sub events a mouse double click event involves?
A hidden column is used to when a column has to embed into boilerplate text.
241. What database aspects should be monitored? (for DBA
One should implement a monitoring system to constantly monitor the following aspects of a database. Writing custom scripts, implementing Oracle's Enterprise Manager, or buying a third-party monitoring product can achieve this. If an alarm is triggered, the system should automatically notify the DBA (e-mail, page, etc.) to take appropriate action.
Infrastructure availability:
. Is the database up and responding to requests
. Are the listeners up and responding to requests
. Are the Oracle Names and LDAP Servers up and responding to requests
. Are the Web Listeners up and responding to requests
Things that can cause service outages:
. Is the archive log destination filling up?
. Objects getting close to their max extents
. User and process limits reached
Things that can cause bad performance:
See question "What tuning indicators can one use?".
242. Where should the tuning effort be directed? (for DBA
Consider the following areas for tuning. The order in which steps are listed needs to be maintained to prevent tuning side effects. For example, it is no good increasing the buffer cache if you can reduce I/O by rewriting a SQL statement.
Database Design (if it's not too late):
Poor system performance usually results from a poor database design. One should generally normalize to the 3NF. Selective denormalization can provide valuable performance improvements. When designing, always keep the "data access path" in mind. Also look at proper data partitioning, data replication, aggregation tables for decision support systems, etc.
Application Tuning:
Experience showed that approximately 80% of all Oracle system performance problems are resolved by coding optimal SQL. Also consider proper scheduling of batch tasks after peak working hours.
Memory Tuning:
Properly size your database buffers (shared pool, buffer cache, log buffer, etc) by looking at your buffer hit ratios. Pin large objects into memory to prevent frequent reloads.
Disk I/O Tuning:
Database files needs to be properly sized and placed to provide maximum disk subsystem throughput. Also look for frequent disk sorts, full table scans, missing indexes, row chaining, data fragmentation, etc
Eliminate Database Contention:
Study database locks, latches and wait events carefully and eliminate where possible.
Tune the Operating System:
Monitor and tune operating system CPU, I/O and memory utilization. For more information, read the related Oracle FAQ dealing with your specific operating system.
243. What are the various sub events a mouse double click event involves?
What are the various sub events a mouse double click event involves?
Double clicking the mouse consists of the mouse down, mouse up, mouse click, mouse down & mouse up events.
245. What are the default parameter that appear at run time in the parameter screen?
What are the various sub events a mouse double click event involves?
Destype and Desname.
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