PL / SQL Interview

1. What is Log Switch? - The point at which ORACLE ends writing to one online redo log file and begins writing to another is called a log switch.
2. What is On-line Redo Log? - The On-line Redo Log is a set of tow or more on-line redo files that record all committed changes made to the database. Whenever a transaction is committed, the corresponding redo entries temporarily stores in redo log buffers of the SGA are written to an on-line redo log file by the background process LGWR. The on-line redo log files are used in cyclical fashion.
3. Which parameter specified in the DEFAULT STORAGE clause of CREATE TABLESPACE cannot be altered after creating the tablespace? - All the default storage parameters defined for the tablespace can be changed using the ALTER TABLESPACE command. When objects are created their INITIAL and MINEXTENS values cannot be changed.
4. What are the steps involved in Database Startup? - Start an instance, Mount the Database and Open the Database.
5. What are the steps involved in Instance Recovery? - Rolling forward to recover data that has not been recorded in data files, yet has been recorded in the on-line redo log, including the contents of rollback segments. Rolling back transactions that have been explicitly rolled back or have not been committed as indicated by the rollback segments regenerated in step a. Releasing any resources (locks) held by transactions in process at the time of the failure. Resolving any pending distributed transactions undergoing a two-phase commit at the time of the instance failure.
6. Can Full Backup be performed when the database is open? - No.
7. What are the different modes of mounting a Database with the Parallel Server? - Exclusive Mode If the first instance that mounts a database does so in exclusive mode, only that Instance can mount the database. Parallel Mode If the first instance that mounts a database is started in parallel mode, other instances that are started in parallel mode can also mount the database.
8. What are the advantages of operating a database in ARCHIVELOG mode over operating it in NO ARCHIVELOG mode? - Complete database recovery from disk failure is possible only in ARCHIVELOG mode. Online database backup is possible only in ARCHIVELOG mode.
9. What are the steps involved in Database Shutdown? - Close the Database, Dismount the Database and Shutdown the Instance.
10. What is Archived Redo Log? - Archived Redo Log consists of Redo Log files that have archived before being reused.
11. What is Restricted Mode of Instance Startup? - An instance can be started in (or later altered to be in) restricted mode so that when the database is open connections are limited only to those whose user accounts have been granted the RESTRICTED SESSION system privilege.
12. What is Partial Backup? - A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.
13. What is Mirrored on-line Redo Log? - A mirrored on-line redo log consists of copies of on-line redo log files physically located on separate disks, changes made to one member of the group are made to all members.
14. What is Full Backup? - A full backup is an operating system backup of all data files, on- line redo log files and control file that constitute ORACLE database and the parameter.
15. Can a View based on another View? - Yes.
16. Can a Tablespace hold objects from different Schemes? - Yes.
17. Can objects of the same Schema reside in different tablespaces? - Yes.
18. What is the use of Control File? - When an instance of an ORACLE database is started, its control file is used to identify the database and redo log files that must be opened for database operation to proceed. It is also used in database recovery.
19. Do View contain Data? - Views do not contain or store data.
20. What are the Referential actions supported by FOREIGN KEY integrity constraint? - UPDATE and DELETE Restrict - A referential integrity rule that disallows the update or deletion of referenced data. DELETE Cascade - When a referenced row is deleted all associated dependent rows are deleted.
21. What are the type of Synonyms? - There are two types of Synonyms Private and Public
22. What is a Redo Log? - The set of Redo Log files YSDATE,UID,USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.
23. What is an Index Segment? - Each Index has an Index segment that stores all of its data.
24. Explain the relationship among Database, Tablespace and Data file.? - Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace
25. What are the different type of Segments? - Data Segment, Index Segment, Rollback Segment and Temporary Segment.
26. What are Clusters? - Clusters are groups of one or more tables physically stores together to share common columns and are often used together.
27. What is an Integrity Constrains? - An integrity constraint is a declarative way to define a business rule for a column of a table.
28. What is an Index? - An Index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
29. What is an Extent? - An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and used to store a specific type of information.
30. What is a View? - A view is a virtual table. Every view has a Query attached to it. (The Query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)
31. What is Table? - A table is the basic unit of data storage in an ORACLE database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.
32. What is a Synonym? - A synonym is an alias for a table, view, sequence or program unit.
33. What is a Sequence? - A sequence generates a serial list of unique numbers for numerical columns of a database’s tables.
34. What is a Segment? - A segment is a set of extents allocated for a certain logical structure.
35. What is schema? - A schema is collection of database objects of a User.
36. Describe Referential Integrity? - A rule defined on a column (or set of columns) in one table that allows the insert or update of a row only if the value for the column or set of columns (the dependent value) matches a value in a column of a related table (the referenced value). It also specifies the type of data manipulation allowed on referenced data and the action to be performed on dependent data as a result of any action on referenced data.
37. What is Hash Cluster? - A row is stored in a hash cluster based on the result of applying a hash function to the row’s cluster key value. All rows with the same hash key value are stores together on disk.
38. What is a Private Synonyms? - A Private Synonyms can be accessed only by the owner.
39. What is Database Link? - A database link is a named object that describes a “path” from one database to another.
40. What is a Tablespace? - A database is divided into Logical Storage Unit called tablespaces. A tablespace is used to grouped related logical structures together
41. What is Rollback Segment? - A Database contains one or more Rollback Segments to temporarily store “undo” information.
42. What are the Characteristics of Data Files? - A data file can be associated with only one database. Once created a data file can’t change size. One or more data files form a logical unit of database storage called a tablespace.
43. How to define Data Block size? - A data block size is specified for each ORACLE database when the database is created. A database users and allocated free database space in ORACLE datablocks. Block size is specified in INIT.ORA file and can’t be changed latter.
44. What does a Control file Contain? - A Control file records the physical structure of the database. It contains the following information. Database Name Names and locations of a database’s files and redolog files. Time stamp of database creation.
45. What is difference between UNIQUE constraint and PRIMARY KEY constraint? - A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can’t contain Nulls. 47.What is Index Cluster? - A Cluster with an index on the Cluster Key 48.When does a Transaction end? - When it is committed or Rollbacked.
46. What is the effect of setting the value “ALL_ROWS” for OPTIMIZER_GOAL parameter of the ALTER SESSION command? - What are the factors that affect OPTIMIZER in choosing an Optimization approach? - Answer The OPTIMIZER_MODE initialization parameter Statistics in the Data Dictionary the OPTIMIZER_GOAL parameter of the ALTER SESSION command hints in the statement.
47. What is the effect of setting the value “CHOOSE” for OPTIMIZER_GOAL, parameter of the ALTER SESSION Command? - The Optimizer chooses Cost_based approach and optimizes with the goal of best throughput if statistics for atleast one of the tables accessed by the SQL statement exist in the data dictionary. Otherwise the OPTIMIZER chooses RULE_based approach.
48. What is the function of Optimizer? - The goal of the optimizer is to choose the most efficient way to execute a SQL statement.
49. What is Execution Plan? - The combinations of the steps the optimizer chooses to execute a statement is called an execution plan.
50. What are the different approaches used by Optimizer in choosing an execution plan? - Rule-based and Cost-based.
Categories: Database
DBA Interview Questions - Part 2
1. What does ROLLBACK do? - ROLLBACK retracts any of the changes resulting from the SQL statements in the transaction.
2. What is SAVE POINT? - For long transactions that contain many SQL statements, intermediate markers or savepoints can be declared which can be used to divide a transaction into smaller parts. This allows the option of later rolling back all work performed from the current point in the transaction to a declared savepoint within the transaction.
3. What are the values that can be specified for OPTIMIZER MODE Parameter? - COST and RULE.
4. What is COST-based approach to optimization? - Considering available access paths and determining the most efficient execution plan based on statistics in the data dictionary for the tables accessed by the statement and their associated clusters and indexes.
5. What does COMMIT do? - COMMIT makes permanent the changes resulting from all SQL statements in the transaction. The changes made by the SQL statements of a transaction become visible to other user sessions transactions that start only after transaction is committed.
6. What is RULE-based approach to optimization? - Choosing an executing plan based on the access paths available and the ranks of these access paths.
7. What are the values that can be specified for OPTIMIZER_GOAL parameter of the ALTER SESSION Command? - CHOOSE,ALL_ROWS,FIRST_ROWS and RULE.
8. Define Transaction? - A Transaction is a logical unit of work that comprises one or more SQL statements executed by a single user.
9. What is Read-Only Transaction? - A Read-Only transaction ensures that the results of each query executed in the transaction are consistent with respect to the same point in time.
10. What is a deadlock? - Explain . Two processes waiting to update the rows of a table which are locked by the other process then deadlock arises. In a database environment this will often happen because of not issuing proper row lock commands. Poor design of front-end application may cause this situation and the performance of server will reduce drastically. These locks will be released automatically when a commit/rollback operation performed or any one of this processes being killed externally.
11. What is a Schema? - The set of objects owned by user account is called the schema.
12. What is a cluster Key? - The related columns of the tables are called the cluster key. The cluster key is indexed using a cluster index and its value is stored only once for multiple tables in the cluster.
13. What is Parallel Server? - Multiple instances accessing the same database (Only In Multi-CPU environments)
14. What are the basic element of Base configuration of an oracle Database? - It consists of one or more data files. one or more control files. two or more redo log files. The Database contains multiple users/schemas one or more rollback segments one or more tablespaces Data dictionary tables User objects (table, indexes, views etc.,) The server that access the database consists of SGA (Database buffer, Dictionary Cache Buffers, Redo log buffers, Shared SQL pool) SMON (System MONito) PMON (Process MONitor) LGWR (LoG Write) DBWR (Data Base Write) ARCH (ARCHiver) CKPT (Check Point) RECO Dispatcher User Process with associated PGS
15. What is clusters? - Group of tables physically stored together because they share common columns and are often used together is called Cluster.
16. What is an Index? - How it is implemented in Oracle Database? - An index is a database structure used by the server to have direct access of a row in a table. An index is automatically created when a unique of primary key constraint clause is specified in create table command (Ver 7.0)
17. What is a Database instance? - Explain A database instance (Server) is a set of memory structure and background processes that access a set of database files. The process can be shared by all users. The memory structure that are used to store most queried data from database. This helps up to improve database performance by decreasing the amount of I/O performed against data file.
18. What is the use of ANALYZE command? - To perform one of these function on an index, table, or cluster: - To collect statistics about object used by the optimizer and store them in the data dictionary. - To delete statistics about the object used by object from the data dictionary. - To validate the structure of the object.. - To identify migrated and chained rows off the table or cluster.
19. What is default tablespace? - The Tablespace to contain schema objects created without specifying a tablespace name.
20. What are the system resources that can be controlled through Profile? - The number of concurrent sessions the user can establish the CPU processing time available to the user’s session the CPU processing time available to a single call to ORACLE made by a SQL statement the amount of logical I/O available to the user’s session the amount of logical I/O available to a single call to ORACLE made by a SQL statement the allowed amount of idle time for the user’s session the allowed amount of connect time for the user’s session.
21. What is Tablespace Quota? - The collective amount of disk space available to the objects in a schema on a particular tablespace.
22. What are the different Levels of Auditing? - Statement Auditing, Privilege Auditing and Object Auditing.
23. What is Statement Auditing? - Statement auditing is the auditing of the powerful system privileges without regard to specifically named objects
24. What are the database administrators utilities available? - SQL * DBA - This allows DBA to monitor and control an ORACLE database. SQL * Loader - It loads data from standard operating system files (Flat files) into ORACLE database tables. Export (EXP) and Import (imp) utilities allow you to move existing data in ORACLE format to and from ORACLE database.
25. How can you enable automatic archiving? - Shut the database Backup the database Modify/Include LOG_ARCHIVE_START_TRUE in init.ora file. Start up the database.
26. What are roles? - How can we implement roles? - Roles are the easiest way to grant and manage common privileges needed by different groups of database users. Creating roles and assigning provides to roles. Assign each role to group of users. This will simplify the job of assigning privileges to individual users.
27. What are Roles? - Roles are named groups of related privileges that are granted to users or other roles.
28. What are the use of Roles? - REDUCED GRANTING OF PRIVILEGES - Rather than explicitly granting the same set of privileges to many users a database administrator can grant the privileges for a group of related users granted to a role and then grant only the role to each member of the group. DYNAMIC PRIVILEGE MANAGEMENT - When the privileges of a group must change, only the privileges of the role need to be modified. The security domains of all users granted the group’s role automatically reflect the changes made to the role. SELECTIVE AVAILABILITY OF PRIVILEGES - The roles granted to a user can be selectively enable (available for use) or disabled (not available for use). This allows specific control of a user’s privileges in any given situation. APPLICATION AWARENESS - A database application can be designed to automatically enable and disable selective roles when a user attempts to use the application.
29. What is Privilege Auditing? - Privilege auditing is the auditing of the use of powerful system privileges without regard to specifically named objects.
30. What is Object Auditing? - Object auditing is the auditing of accesses to specific schema objects without regard to user.
31. What is Auditing? - Monitoring of user access to aid in the investigation of database use.
32. What are the responsibilities of a Database Administrator?
o Installing and upgrading the Oracle Server and application tools.
o Allocating system storage and planning future storage requirements for the database system.
o Managing primary database structures (tablespaces)
o Managing primary objects (table, views, indexes)
o Enrolling users and maintaining system security.
o Ensuring compliance with Oracle license agreement
o Controlling and monitoring user access to the database.
o Monitoring and optimizing the performance of the database.
o Planning for backup and recovery of database information.
o Maintain archived data on tape
o Backing up and restoring the database.
o Contacting Oracle Corporation for technical support.
33. What is a trace file and how is it created? - Each server and background process can write an associated trace file. When an internal error is detected by a process or user process, it dumps information about the error to its trace. This can be used for tuning the database.
34. What is a profile? - Each database user is assigned a Profile that specifies limitations on various system resources available to the user.
35. How will you enforce security using stored procedures? - Don’t grant user access directly to tables within the application. Instead grant the ability to access the procedures that access the tables. When procedure executed it will execute the privilege of procedures owner. Users cannot access tables except via the procedure.
Categories: Database
1. What are the dictionary tables used to monitor a database spaces? - DBA_FREE_SPACE DBA_SEGMENTS DBA_DATA_FILES.
2. What are the roles and user accounts created automatically with the database? - DBA - role Contains all database system privileges. SYS user account - The DBA role will be assigned to this account. All of the base tables and views for the database’s dictionary are store in this schema and are manipulated only by ORACLE. SYSTEM user account - It has all the system privileges for the database and additional tables and views that display administrative information and internal tables and views used by oracle tools are created using this username.
3. What are the minimum parameters should exist in the parameter file (init.ora)? - DB NAME - Must set to a text string of no more than 8 characters and it will be stored inside the datafiles, redo log files and control files and control file while database creation. DB_DOMAIN - It is string that specifies the network domain where the database is created. The global database name is identified by setting these parameters (DB_NAME & DB_DOMAIN) CONTORL FILES - List of control filenames of the database. If name is not mentioned then default name will be used. DB_BLOCK_BUFFERS - To determine the no of buffers in the buffer cache in SGA. PROCESSES - To determine number of operating system processes that can be connected to ORACLE concurrently. The value should be 5 (background process) and additional 1 for each user. ROLLBACK_SEGMENTS - List of rollback segments an ORACLE instance acquires at database startup. Also optionally LICENSE_MAX_SESSIONS,LICENSE_SESSION_WARNING and LICENSE_MAX_USERS.
4. How can we specify the Archived log file name format and destination? - By setting the following values in init.ora file. LOG_ARCHIVE_FORMAT = arch %S/s/T/tarc (%S - Log sequence number and is zero left padded, %s - Log sequence number not padded. %T - Thread number left-zero- padded and %t - Thread number not padded). The file name created is arch 0001 are if %S is used. LOG_ARCHIVE_DEST = path.
5. What is user Account in Oracle database? - An user account is not a physical structure in Database but it is having important relationship to the objects in the database and will be having certain privileges. 95. When will the data in the snapshot log be used? - We must be able to create a after row trigger on table (i.e., it should be not be already available) After giving table privileges. We cannot specify snapshot log name because oracle uses the name of the master table in the name of the database objects that support its snapshot log. The master table name should be less than or equal to 23 characters. (The table name created will be MLOGS_tablename, and trigger name will be TLOGS name).
6. What dynamic data replication? - Updating or Inserting records in remote database through database triggers. It may fail if remote database is having any problem.
7. What is Two-Phase Commit? - Two-phase commit is mechanism that guarantees a distributed transaction either commits on all involved nodes or rolls back on all involved nodes to maintain data consistency across the global distributed database. It has two phase, a Prepare Phase and a Commit Phase.
8. How can you Enforce Referential Integrity in snapshots? - Time the references to occur when master tables are not in use. Peform the reference the manually immdiately locking the master tables. We can join tables in snopshots by creating a complex snapshots that will based on the master tables.
9. What is a SQL * NET? - SQL *NET is ORACLE’s mechanism for interfacing with the communication protocols used by the networks that facilitate distributed processing and distributed databases. It is used in Clint-Server and Server-Server communications.
10. What is a SNAPSHOT? - Snapshots are read-only copies of a master table located on a remote node which is periodically refreshed to reflect changes made to the master table.
11. What is the mechanism provided by ORACLE for table replication? - Snapshots and SNAPSHOT LOGs
12. What is snapshots? - Snapshot is an object used to dynamically replicate data between distribute database at specified time intervals. In ver 7.0 they are read only.
13. What are the various type of snapshots? - Simple and Complex.
14. Describe two phases of Two-phase commit? - Prepare phase - The global coordinator (initiating node) ask a participants to prepare (to promise to commit or rollback the transaction, even if there is a failure) Commit - Phase - If all participants respond to the coordinator that they are prepared, the coordinator asks all nodes to commit the transaction, if all participants cannot prepare, the coordinator asks all nodes to roll back the transaction.
15. What is snapshot log? - It is a table that maintains a record of modifications to the master table in a snapshot. It is stored in the same database as master table and is only available for simple snapshots. It should be created before creating snapshots.
16. What are the benefits of distributed options in databases? - Database on other servers can be updated and those transactions can be grouped together with others in a logical unit. Database uses a two phase commit.
17. What are the options available to refresh snapshots? - COMPLETE - Tables are completely regenerated using the snapshots query and the master tables every time the snapshot referenced. FAST - If simple snapshot used then a snapshot log can be used to send the changes to the snapshot tables. FORCE - Default value. If possible it performs a FAST refresh; Otherwise it will perform a complete refresh.
18. What is a SNAPSHOT LOG? - A snapshot log is a table in the master database that is associated with the master table. ORACLE uses a snapshot log to track the rows that have been updated in the master table. Snapshot logs are used in updating the snapshots based on the master table.
19. What is Distributed database? - A distributed database is a network of databases managed by multiple database servers that appears to a user as single logical database. The data of all databases in the distributed database can be simultaneously accessed and modified.
20. How can we reduce the network traffic? - Replication of data in distributed environment. - Using snapshots to replicate data. - Using remote procedure calls.
21. Differentiate simple and complex, snapshots? - A simple snapshot is based on a query thaat does not contains GROUP BY clauses, CONNECT BY clauses, JOINs, sub-query or snapshot of operations. - A complex snapshots contain at least any one of the above.
22. What are the Built-ins used for sending Parameters to forms? - You can pass parameter values to a form when an application executes the call_form, New_form, Open_form or Run_product.
23. Can you have more than one content canvas view attached with a window? - Yes. Each window you create must have at least one content canvas view assigned to it. You can also create a window that has manipulated content canvas view. At run time only one of the content canvas views assign to a window is displayed at a time.
DBA Interview Questions - Part 4
1. Is the After report trigger fired if the report execution fails? - Yes.
2. Does a Before form trigger fire when the parameter form is suppressed? - Yes.
3. Is it possible to split the print reviewer into more than one region? - Yes
4. Is it possible to center an object horizontally in a repeating frame that has a variable horizontal size? - Yes
5. For a field in a repeating frame, can the source come from the column which does not exist in the data group which forms the base for the frame? - Yes
6. Can a field be used in a report without it appearing in any data group? - Yes
7. The join defined by the default data link is an outer join yes or no? - Yes
8. Can a formula column referred to columns in higher group? - Yes
9. Can a formula column be obtained through a select statement? - Yes
10. Is it possible to insert comments into sql statements return in the data model editor? - Yes
11. Is it possible to disable the parameter from while running the report? - Yes
12. When a form is invoked with call_form, Does oracle forms issues a save point? - Yes
13. Can a property clause itself be based on a property clause? - Yes
14. If a parameter is used in a query without being previously defined, what diff. exist between report 2.0 and 2.5 when the query is applied? - While both reports 2.0 and 2.5 create the parameter, report 2.5 gives a message that a bind parameter has been created.
15. What are the SQL clauses supported in the link property sheet? - Where start with having.
16. What is trigger associated with the timer? - When-timer-expired.
17. What are the trigger associated with image items? - When-image-activated fires when the operators double clicks on an image itemwhen-image-pressed fires when an operator clicks or double clicks on an image item
18. What are the different windows events activated at runtimes? - When_window_activated When_window_closed When_window_deactivated When_window_resized Within this triggers, you can examine the built in system variable system. event_window to determine the name of the window for which the trigger fired.
19. When do you use data parameter type? - When the value of a data parameter being passed to a called product is always the name of the record group defined in the current form. Data parameters are used to pass data to produts invoked with the run_product built-in subprogram.
20. What is difference between open_form and call_form? - when one form invokes another form by executing open_form the first form remains displayed, and operators can navigate between the forms as desired. when one form invokes another form by executing call_form, the called form is modal with respect to the calling form. That is, any windows that belong to the calling form are disabled, and operators cannot navigate to them until they first exit the called form.
21. What is new_form built-in? - When one form invokes another form by executing new_form oracle form exits the first form and releases its memory before loading the new form calling new form completely replace the first with the second. If there are changes pending in the first form, the operator will be prompted to save them before the new form is loaded.
22. What is the “LOV of Validation” Property of an item? - What is the use of it? - When LOV for Validation is set to True, Oracle Forms compares the current value of the text item to the values in the first column displayed in the LOV. Whenever the validation event occurs. If the value in the text item matches one of the values in the first column of the LOV, validation succeeds, the LOV is not displayed, and processing continues normally. If the value in the text item does not match one of the values in the first column of the LOV, Oracle Forms displays the LOV and uses the text item value as the search criteria to automatically reduce the list.
23. What is the diff. when Flex mode is mode on and when it is off? - When flex mode is on, reports automatically resizes the parent when the child is resized.
24. What is the diff. when confine mode is on and when it is off? - When confine mode is on, an object cannot be moved outside its parent in the layout.
25. What are visual attributes? - Visual attributes are the font, color, pattern proprieties that you set for form and menu objects that appear in your application interface.
26. Which of the two views should objects according to possession? - view by structure.
27. What are the two types of views available in the object navigator (specific to report 2.5)? - View by structure and view by type .
28. What are the vbx controls? - Vbx control provide a simple method of building and enhancing user interfaces. The controls can use to obtain user inputs and display program outputs.vbx control where originally develop as extensions for the ms visual basic environments and include such items as sliders, rides and knobs.
29. What is the use of transactional triggers? - Using transactional triggers we can control or modify the default functionality of the oracle forms.
30. How do you create a new session while open a new form? - Using open_form built-in setting the session option Ex. Open_form (’Stocks ‘,active,session). when invoke the mulitiple forms with open form and call_form in the same application, state whether the following are true/False
31. What are the ways to monitor the performance of the report? - Use reports profile executable statement. Use SQL trace facility.
32. If two groups are not linked in the data model editor, What is the hierarchy between them? - Two group that is above are the left most rank higher than the group that is to right or below it.
33. An open form can not be execute the call_form procedure if you chain of called forms has been initiated by another open form? - True
34. Explain about horizontal, Vertical tool bar canvas views? - Tool bar canvas views are used to create tool bars for individual windows. Horizontal tool bars are display at the top of a window, just under its menu bar. Vertical Tool bars are displayed along the left side of a window
35. What is the purpose of the product order option in the column property sheet? - To specify the order of individual group evaluation in a cross products.
36. What is the use of image_zoom built-in? - To manipulate images in image items.
How do you reference a parameter indirectly? - To indirectly reference a parameter use the NAME IN, COPY ‘built-ins to indirectly set and reference the parameters value’ Example name_in (’capital parameter my param’), Copy (’SURESH’,'Parameter my_param’)
1. What are the advantages of operating a database in
ARCHIVELOG mode over operating it in NO ARCHIVELOG mode ?

Complete database recovery from disk failure is possible
only in ARCHIVELOG mode.

Online database backup is possible only in ARCHIVELOG mode.
What is Archived Redo Log ?
Archived Redo Log consists of Redo Log files that have
archived before being reused.
What is Mirrored on-line Redo Log ?
A mirrored on-line redo log consists of copies of on-line
redo log files physically located on separate disks,
changes made to one member of the group are made to all members.
What is On-line Redo Log?
The On-line Redo Log is a set of tow or more on-line redo
files that record all committed changes made to the
database. Whenever a transaction is committed, the
corresponding redo entries temporarily stores in redo log
buffers of the SGA are written to an on-line redo
log file by the background process LGWR. The on-line redo
log files are used in cyclical fashion.
What is Partial Backup ?
A Partial Backup is any operating system backup short of
a full backup, taken while the database is open or shut down.
Can Full Backup be performed when the database is open
No.
What is Full Backup ?
A full backup is an operating system backup of all data
files, on-line redo log files and control file that
constitute ORACLE database and the parameter.
What are the different modes of mounting a Database with
the Parallel Server ?
Exclusive Mode If the first instance that mounts a
database does so in exclusive mode, only that Instance can
mount the database.

Parallel Mode If the first instance that mounts a
database is started in parallel mode, other instances that
are started in parallel mode can also mount the database.
What is Restricted Mode of Instance Startup ?
An instance can be started in (or later altered to be in)
restricted mode so that when the database is open
connections are limited only to those whose user accounts
have been granted the RESTRICTED SESSION system privilege.
What are the steps involved in Database Shutdown
Close the Database, Dismount the Database and Shutdown the
Instance.
0
Guest

How free extents are managed in Ver 6.0 and Ver 7.0 ?
Free extents cannot be merged together in Ver 6.0.

Free extents are periodically coalesces with the neighboring
free extent in Ver 7.0
What is Database Buffers ?
Database buffer is part of SGA, Which it is contain oracle
blocks copied from datafile and modification carried in this
area. In oracle 9i BUFFER CACHE is divided into three parts
buffer_cache, buffer_keep_cache,buffer_recycle_cahce.

THANKS
What is the OPTIMAL parameter ?
OPTIMAL parameter is used to set the optimal length of a
rollback segment
How will you monitorthis can be monitored in DB_data_files
the space allocation ?

What is a Rollback segment entry ?TCS
this contains the commited and uncommited data stored in
rollback table space prior to 9i. in 9i, it is called as
undo table space.


What is use of Rollback Segments In Database ?I

TRANSACTION RECOVERY, READ CONSISTENCY
What is the role of PCTFREE parameter is Storage clause ?I
A oracle block divided into three parts.
block header,pctfree,pctused.


block header :its contain the information datafiles.


pctfree: its a free space in a datablock for updation and
insertion of a row.default is 10% of a block size.one more
thing it's default value is depand of OS also.


pctused : its a space where data are store in a block.its
default value is 40% of a block size.
What is meant by redo log buffer ?I
when ever the buffer cache is crashed, the transactions
present in the buffer cache is lost. this can be recovered
by the redo log buffer, which contains all the transactions
present in the buffer cache
List the Optional Flexible Architecture (OFA) of Oracle
database ?I
SYSTEM - Data dictionary tables.
DATA - Standard operational tables.
DATA2- Static tables used for standard operations
INDEXES - Indexes for Standard operational tables.
INDEXES1 - Indexes of static tables used for standard
operations.
TOOLS - Tools table.
TOOLS1 - Indexes for tools table.
RBS - Standard Operations Rollback Segments,
RBS1,RBS2 - Additional/Special Rollback segments.
TEMP - Temporary purpose tablespace
TEMP_USER - Temporary tablespace for users.
USERS - User tablespace.
What is meant by free extent ?I
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.
List the factors that can affect the accuracy of the
estimations ?I
The space used transaction entries and deleted records does
not become free immediately after completion due to delayed
cleanout.

Trailling nulls and length bytes are not stored.


Inserts of, updates to and deletes of rows as well as
columns larger than a single datablock, can cause
fragmentation an chained row pieces.
What is the functionality of SYSTEM table space ?I

system tablespace is a main part of oracle database.All the
database information is in it.it is created when database
is created.
its managed by oracle server.dba cannot change its
containts.
How will you create multiple rollback segments in a
database ?I
CREATE ROLLBACK SEGMENT rbs_one
TABLESPACE rbs_ts
STORAGE
( INITIAL 10K
NEXT 10K
MAXEXTENTS UNLIMITED )
What is advantage of having disk shadowing/ Mirroring ?I

if the original disk has been crashed, the data can be
recovered by using this method. just like raid levels
Moving Datafiles
There are two methods for moving datafiles: via the ALTER DATABASE command, and via the
ALTER TABLESPACE command. The ALTER TABLESPACE method only applies to datafiles
whose tablespaces do not include SYSTEM, rollback segments, or temporary segments. The ALTER
DATABASE method will work for all datafiles.
The ALTER DATABASE Method

When using the ALTER DATABASE method to move datafiles, the datafile is moved after the
instance has been shut down. The steps involved, detailed in the following sections, are:

1. Shutdown the instance, using SQLDBA or Server Manager.
2. Use operating system commands to move the datafile.
3. Mount the database and use the ALTER DATABASE to rename the file within the database.
4. Start the instance, using SQLDBA or Server Manager.

In the following examples, the Oracle7 order of commands is shown.

Step 1. Shutdown the instance, using SQLDBA or Server Manager SQLDBA version:

$ sqldba lmode=y
SQLDBA> connect internal;
SQLDBA> shutdown;
SQLDBA> exit;

Server Manager version:

$ svrmgrl
SVRMGR> connect internal;
SVRMGR> shutdown;
SVRMGR> exit;

Step 2. Use operating system commands to move the datafile. Use an operating system command to move the datafile. In UNIX, the 'mv' command moves files to
new locations. The following example shows the 'data01.dbf' file being moved from the device
named '/db01' to one named '/db02'.

$ mv /db01/oracle/CC1/data01.dbf /db02/oracle/CC1

The file name must fully specify a file name using the conventions of your operating system.

Step 3. Mount the database and use the ALTER DATABASE to rename the file within the database. In the following example, the CC1 instance is started and the 'data01.dbf' datafile moved in Step 2 is
renamed within the database. The database will then be able to find that file during instance startup.
The ALTER DATABASE command shown here does not rename the file; the file must have already
been renamed or moved. If you are using Server Manager, replace the sqldba lmode=y command
with svrmgrl.

$ sqldba lmode=y
SQLDBA> connect internal;
SQLDBA> STARTUP MOUNT CC1;
SQLDBA> ALTER DATABASE RENAME FILE
2> '/db01/oracle/CC1/data01.dbf' TO
3> '/db02/oracle/CC1/data01.dbf';

Do not disconnect after this step is complete; stay logged in to the database and proceed to Step 4.

When the ALTER DATABASE command is executed, Oracle will check to see if the name you are
naming the file 'to' exists. If this step fails, check the accuracy of the destination file name.

Step 4. Start the instance. Now that the database knows how to find the moved file, the instance can start. The following
command should be executed within either SQLDBA or Server Manager.

SQLDBA> alter database open;

The instance will now be opened, using the new location for the datafile that was moved.
The ALTER TABLESPACE Method
When using the ALTER TABLESPACE method to move datafiles, the datafile is moved while the
instance is still running. The steps involved, detailed in the following sections, are:

1. Take the tablespace offline.
2. Use operating system commands to move the file.
3. Use the ALTER TABLESPACE command to rename the file within the database.
4. Bring the tablespace back online.

NOTE: This method can only be used for non-SYSTEM tablespaces. It cannot be used for
tablespaces that contain active rollback segments or temporary segments.

In the following examples, the Oracle7 order of commands is shown.

Take the tablespace offline. Use the ALTER TABLESPACE command to put the tablespace into OFFLINE state, as shown in
the following example. This command is executed while the instance is running. It cannot be used
for the SYSTEM tablespace or for tablespace containing active rollback segments or temporary
segments. If you are using Server Manager, replace the sqldba lmode=y command with svrmgrl to
enter Server Manager's line mode interface.

$ sqldba lmode=y
SQLDBA> connect internal;
SQLDBA> ALTER TABLESPACE data OFFLINE;
SQLDBA> exit;

Use operating system commands to move the file. Use an operating system command to move the datafile. In UNIX, the 'mv' command moves files to
new locations. The following example shows the 'data01.dbf' file being moved from the device
named '/db01' to one named '/db02'.

$ mv /db01/oracle/CC1/data01.dbf /db02/oracle/CC1

The file name must fully specify a file name using the conventions of your operating system.

Use the ALTER TABLESPACE command to rename the file within the database. In the following example, the 'data01.dbf' datafile moved in Step 2 is renamed within the database.
The database will then be able to access that file. The ALTER TABLESPACE command shown here
does not rename the file; the file must have already been renamed or moved. If you are using Server
Manager, replace the sqldba lmode=y command with svrmgrl to enter Server Manager's line mode
interface.

$ sqldba lmode=y
SQLDBA> connect internal;
SQLDBA> ALTER TABLESPACE data RENAME DATAFILE
2> '/db01/oracle/CC1/data01.dbf' TO
3> '/db02/oracle/CC1/data01.dbf';

Do not disconnect after this step is complete; stay logged in to the database and proceed to Step 4.

When the ALTER TABLESPACE command is executed, Oracle will check to see if the name you are
naming the file 'to' exists. If this step fails, check the accuracy of the destination file name.

Bring the tablespace back online. Use the ALTER TABLESPACE command to bring the tablespace back online, from within either
SQLDBA or Server Manager.

SQLDBA> ALTER TABLESPACE data ONLINE;

The DATA tablespace will then be brought back online, using the new location for the datafile.
Moving Online Redo Log Files

Online redo log files can be moved while the database is shut down, and renamed to within the
database via the ALTER DATABASE command. The procedures for moving online redo log files are
very similar to those used to move datafiles via the ALTER DATABASE command.

First, the database is shut down and the online redo log file is moved. The database is then mounted
and the ALTER DATABASE command is used to tell the database the new location of the online redo
log file. The instance can then be opened, using the online redo log file in its new location. In the
following examples, the Oracle7 order of commands is shown.

Step 1. Shutdown the instance.
SQLDBA version:

$ sqldba lmode=y
SQLDBA> connect internal;
SQLDBA> shutdown;
SQLDBA> exit;

Server Manager version:

$ svrmgrl
SVRMGRL> connect internal;
SVRMGRL> shutdown;
SVRMGRL> exit;


Step 2. Move the online redo log file.
Use an operating system command to move the file. In UNIX, the 'mv' command moves files to new
locations. The following example shows the 'redo01CC1.dbf' file being moved from the device
named '/db05' to one named '/db02'.

$ mv /db05/oracle/CC1/redo01CC1.dbf /db02/oracle/CC1

The file name must fully specify a file name using the conventions of your operating system.

Step 3. Mount the database and use the ALTER DATABASE to rename the file within the database.
In the following example, the CC1 instance is started and the 'redo01CC1.dbf' file moved in Step 2 is
renamed within the database. The database will then be able to find that file during instance startup.
The ALTER DATABASE command shown here does not rename the file; the file must have already
been renamed or moved. If you are using Server Manager, replace the sqldba lmode=y command
with svrmgrl to enter Server Manager's line mode interface.

$ sqldba lmode=y
SQLDBA> connect internal;
SQLDBA> STARTUP MOUNT CC1;
SQLDBA> ALTER DATABASE RENAME FILE
2> '/db05/oracle/CC1/redo01CC1.dbf' TO
3> '/db02/oracle/CC1/redo01CC1.dbf';

Do not disconnect after this step is complete; stay logged in to the database and proceed to Step 4.

When the ALTER DATABASE command is executed, Oracle will check to see if the name you are
naming the file 'to' exists. If this step fails, check the accuracy of the destination file name.

Step 4. Start the instance.
Now that the database knows how to find the moved file, the instance can start. The following
command can be executed from within either Server Manager or SQLDBA.

SQLDBA> alter database open;

The instance will now be opened, using the new location for the online redo log file that was moved.
Moving Control Files

The location of control files is specified in the INIT.ORA or CONFIG.ORA file for the instance. In
Oracle7, the CONFIG.ORA file usually maintains this information. To move a control file, you must
shut down the instance, move the file, edit the CONFIG.ORA file, and then restart the instance.

Step 1. Shutdown the instance.
SQLDBA version:

$ sqldba lmode=y
SQLDBA> connect internal;
SQLDBA> shutdown;
SQLDBA> exit;

Server Manager version:

$ svrmgrl
SVRMGRL> connect internal;
SVRMGRL> shutdown;
SVRMGRL> exit;


Step 2. Move the control file.
Use an operating system command to move the file. In UNIX, the 'mv' command moves files to new
locations. The following example shows the 'ctrl1CC1.ctl' file being moved from the device named
'/db05' to one named '/db02'.

$ mv /db05/oracle/CC1/ctrl1CC1.ctl /db02/oracle/CC1

The file name must fully specify a file name using the conventions of your operating system.

Step 3. Edit the CONFIG.ORA file.
The CONFIG.ORA file for an instance is usually located in the /dbs subdirectory under the Oracle
software home directory (in 7.3, this changes slightly; in the /dbs subdirectory, you will find a link to
the file's new home). Its name typically includes the name of the instance - for the CC1 instance, the
CONFIG.ORA file may be named configCC1.ora. The exact name and location of the CONFIG.ORA
file is specified in the INIT.ORA file for the instance (usually located in the same directory, with the
same naming convention applied).

Within the CONFIG.ORA file, there will be an entry for the "control_files" parameter; and example is
shown in the following listing.

control_files = (/db01/oracle/CC1/ctrl1CC1.ctl,
/db03/oracle/CC1/ctrl1CC1.ctl,
/db05/oracle/CC1/ctrl1CC1.ctl)

Edit this entry to reflect the change to the file you moved in Step 2.

control_files = (/db01/oracle/CC1/ctrl1CC1.ctl,
/db03/oracle/CC1/ctrl1CC1.ctl,
/db02/oracle/CC1/ctrl1CC1.ctl)

Step 4. Start the instance.
SQLDBA version:

$ sqldba lmode=y
SQLDBA> connect internal;
SQLDBA> startup;
SQLDBA> exit;

Server Manager version:

$ svrmgrl
SVRMGRL> connect internal;
SVRMGRL> startup;
SVRMGRL> exit;

The instance will then be started, using the control file in its new location.
=======
Kevin Loney is the author of the ORACLE DBA Handbook, 7.3 Edition, coauthor of ORACLE: The
Complete Reference, Electronic Edition, and coauthor of Advanced ORACLE Tuning and
Administration, all published under Osborne/McGraw-Hill's Oracle Press imprint. See
www.osborne.com for scripts and sample chapters
How To Pass Parameters to Procedures?
Store procedures or functions can take parameters. You need to define parameters while defining the procedure, and providing values to parameters while calling the procedure. The script below shows you how to do this:
SQL> CREATE OR REPLACE PROCEDURE DBA_TASK (day VARCHAR2) AS
2 BEGIN
3 IF day = 'MONDAY' THEN
4 DBMS_OUTPUT.PUT_LINE('Checking log files.');
5 ELSIF day = 'FRIDAY' THEN
6 DBMS_OUTPUT.PUT_LINE('Rebuild indexes.');
7 ELSE
8 DBMS_OUTPUT.PUT_LINE('Reading some papers.');
9 END IF;
10 END;
11 /

SQL> EXECUTE DBA_TASK('MONDAY');
Checking log files.

SQL> EXECUTE DBA_TASK('SUNDAY');
Reading some papers.
As you can see, procedures with parameters can make procedures more flexible.
How To Call a Stored Function?
A stored function can be called as part of expression in any PL/SQL statement. One simplest way to call a stored function is to a dummy SELECT statement as shown in the following tutorial script using SQL*Plus:











SQL> CREATE OR REPLACE FUNCTION GET_SITE
2 RETURN VARCHAR2 AS
3 BEGIN
4 RETURN 'FYICentere.com';
5 END;
6 /
Function created.

SQL> SELECT get_site() FROM dual;

GET_SITE()
---------------------------------
FYICentere.com
DUAL is not a real table or view. It is commonly used to with SELECT statement to evaluate expressions.
How To Call a Stored Function with Parameters?
You can define a function that takes parameters, provide values to those parameters when calling the function. Here is a good example of a function with a parameter:
SQL> CREATE OR REPLACE FUNCTION GET_DOUBLE(X NUMBER)
2 RETURN NUMBER AS
3 BEGIN
4 RETURN X * 2;
5 END;
6 /
Function created.

SQL> SELECT GET_DOUBLE(36) FROM DUAL;
GET_DOUBLE(36)
--------------
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