Akadia Information Technology

Die folgende Zusammenfassung ist eine Sammlung von Frequently Asked Questions rund um das Datenbanksystem Oracle.

Inhalt

Wichtige Views

Oracle-8 Database Administration

Oracle-8 Database Tuning

Oracle-8 Backup and Recovery

Oracle-8 New Features for Administrators

Oracle-8 Net8

Wichtige Views

Alle V$Views auslisten:

SELECT view_name from v$fixed_view_definitionWHERE view_name LIKE 'V$%'ORDER BY view_name;

View Name

Description

V$FILESTAT

Statistics for tuning I/O?Which view would you query to monitor I/O contention for datafiles?

V$SYSTEM_EVENT

Total waits for "buffer busy waits" since instance startup?

V$LOCK,V$LOCKED_OBJECT

Which two views could you query to determine lockcontention on the EMP table?

V$DB_OBJECT_CACHE

Which view can be queried to check the amount of sharablememory used by a cached object?

V$SYSSTAT

Statistics for Redo Log Buffer

V$SYSTEM_EVENT,V$SESSION_WAITV$SESSION_EVENT

Which three views should you use to determine if a processhas waited for a resource?

$DATAFILE_HEADER

Which data dictionary view would you query to determine if a datafile is in backup mode?

V$SESSION_LONGOPS

Which data dictionary view can you query to check the progressof a backup?

V$BACKUP

To see which Files are in BEGIN BACKUP MODE

Oracle-8 Database Administration

Which command will verify the integrity of each block in a tableand validate all of the indexes on this table ?

analyze table dept validate structure cascade;

You need to export the ORDERS table in an open database with no users connected. How could you place the database in restriced session, to allow only users with RESTRICTED SESSION system privilege to logon to Oracle ?

alter system enable restricted session;

Which command would you use to add a datafile to an existing tablespace ?

alter tablespace TAB nologging add datafile '....' ....;

When would a temporary segment, created in a temporary tablespace of typeTEMPORARY, be released ?

When the instance is shut down

Which data dictionary view could you query to display the number of blocksused by a table in each datafile ?

DBA_EXTENTSOWNER VARCHAR2(30)SEGMENT_NAME VARCHAR2(81)PARTITION_NAME VARCHAR2(30)SEGMENT_TYPE VARCHAR2(17)TABLESPACE_NAME VARCHAR2(30)EXTENT_ID NOT NULL NUMBERFILE_ID NOT NULL NUMBERBLOCK_ID NOT NULL NUMBERBYTES NUMBERBLOCKS NOT NULL NUMBERRELATIVE_FNO NOT NULL NUMBER

An User account has been locked by the system. How would you unlock this accountwithout dropping the objects in his schema

alter user scott account unlock;alter user scott account lock;

With which functions could you use the NLS_CURRENCY paramter ?

Only with TO_CHAR and TO_DATE

Which two views could you query to display the names and locations of allcontrolfiles in a database ?

V$CONTROLFILE and V$SYSTEM_PARAMETER

Which data type allows to store multiple values within the same table column ?

VARRAY

When a user issues an UPDATE command, what happens after copies of the blocks are read into the buffer cache and before the changes are recorded in the redo log buffer ?

The Server places locks on the data

You are creating a rollback segment for an application. You have not yet determined the space needed by the average transaction. To which value should you set the OPTIMAL parameter when creating the rollback segment ?

Value greather than or equal to INITIAL * MINEXTENTS

What does a value of -1 in a user's tablespace quota indicate ?

Unlimited quota

If a database cannot be shut down, which command could you use to enable or disable enforcement of resource limits for an existing user during their current session ?

alter system set resource_limit=true;

Which storage parameter could cause higher processing costs because blockswill be considered free more often ?

raising PCTUSED

Which command could you use to create a table with a foreign key beforecreating the table containing the referenced key ?

CREATE SCHEMA

Which characteristics correctly describe extents ?

- Each segment in a database is created with at least one extent.- Frequent de-allocation of extents can lead to a fragmented tablespace.

When does DBWR flush dirty buffers to a datafile?

Either before or after a COMMIT is issued

Which benefit does Oracle Fast COMMIT offer?

Minimal information is required to record the changes in the redo logs, due LRU is deferred.

Writes to the datafiles are deferred to reduce disk contention and I/O. Oracle's Fast COMMIT allows LGWR to record only the changes and SCN in the redo log files. The size of the transaction does not affect the time required to write to the redo log files. These writes are sequential and faster than writing entire blocks to the datafiles. Writes to the datafiles occur independently of the COMMIT.

Which two Server Manager line mode commands could you use to displaythe current size of the redo log buffer?

SHOW SGASHOW PARAMETER

Evaluate this Server Manager line mode command:

ALTER SYSTEM SET SORT_AREA_SIZE=163840 DEFERRED;

What affect would this command have on the SORT_AREA_SIZE initialization parameter?

It will be set to 163840 for all future sessions.

Which SHUTDOWN mode will only wait for the pending transaction of a current user to end before ending their session?

TRANSACTIONAL

Why would you set the REMOTE_LOGIN_PASSWORDFILE initialization parameter to NONE?

To use operating system authentication

To allow users to connect to the database using O/S authentication, set up the users in the operating system and set the REMOTE_LOGIN_PASSWORDFILE initialization parameter to NONE. To connect to the database using the SYSDBA role, log in to the operating system and connect to the database using this connect string: CONNECT / AS SYSDBA

If you administer several remote databases, how would using Oracle Enterprise Manager help you maintain the initialization parameters?

Database configurations can be stored in the OEM registry and not as external files.

Which SHUTDOWN mode waits for all current users to disconnect before shutting down the instance?

NORMAL

Why should the DBA check the ALERT file regularly?

To detect block corruption errors

Using Server Manager line mode, which three methods could you use to display the current locations of the control files for the current instance?

V$PARAMETER, V$CONTROLFILE, SHOW PARAMETER

You start an instance in NOMOUNT state. Which three dynamic performance views can you query?

V$SESSION, V$INSTANCE, V$PARAMETER

When an instance is started in NOMOUNT state, you can only access the views that read data from the SGA. V$PARAMETER, V$SESSION, and V$INSTANCE read from memory; V$DATABASE, V$DATAFILE and V$LOGFILE all read data from the control file. The database must be mounted for the control file to be opened. The data dictionary is only accessible when the database is open.

Which SHUTDOWN mode will only wait for the pending transaction of a current user to end before ending their session?

SHUTDOWN TRANSACTIONAL;

What would happen if the database name in the parameter file does not match the control file?

An instance would start, but the database would not be mounted.

When a database is created, the database name is specified in the CREATE DATABASE command and it must match the DB_NAME parameter. The database will not mount if the database name recorded in the control file does not match the database name in the STARTUP command.

Evaluate this command:

CREATE DATABASE prodMAXLOGFILES 5MAXLOGMEMBERS 5MAXDATAFILES 100MAXLOGHISTORY 100LOGFILEGROUP 1 '/disk3/log1a.rdo, /disk4/log1b.rdo',GROUP 2 '/disk3/log2a.rdo, /disk4/log2b.rdo' REUSEDATAFILE '/disk2/system01.dbf' SIZE 50M;

Which line will return an error under any condition?

==> GROUP 1 '/disk3/log1a.rdo, /disk4/log1b.rdo',

For any datafiles or redo log files that already exist, use the REUSE option in the CREATE DATABASE command. If the file does not exist, you must use the SIZE option to specify the size of the file to be created either in kilobytes (K) or megabytes (M).

According to the Optimal Flexible Architecture, how should you organize your database files?

Directly below the Oracle directory

When planning your database configuration, how should you organize the data storage?

Separate objects by lifespans to minimize fragmentation.

You issued a CREATE DATABASE command that failed because you were attempting to create log files that already existed. What should you do before reissuing the command?

Shut down the instance, delete any files created by the CREATE DATABASE command, and change the SIZE options to REUSE in the LOGFILE parameter of the CREATE DATABASE command.

Why must you recreate the control file if you change the MAXDATAFILES parameter for the PROD database?

To reallocate the space needed for the parameter

You need to be able to perform tablespace-point-in-time recovery. Which script creates the view used by the DBA when performing this type of recovery?

CATPROC.SQL

Which data dictionary category would a user with the SELECT ANY TABLE privilege query to find the owner of the PRODUCT1 table?

The data dictionary views categories:

ALL_

Accessible to all users and each view has an OWNER column, providing information on objects accessible by the user

DBA_

Accessible to the DBA or anyone with the SELECT ANY TABLE privilege, providing information on all the objects in the database and has an OWNER column

USER_

Accessible to all users, providing information on objects owned by the user

Which table contains the names of all the data dictionary views?

The DICTIONARY and DICT_COLUMNS data dictionary views provide an overview for all the data dictionary views.

Which category of scripts contain database package specifications and are usually run during the execution of catproc.sql?

dbms*.sql defines the database package specificationscat*.sql provides catalog and data dictionary informationprvt*.plb provides wrapped package codeutl*sql creates views and tables for database utilities.

Which data dictionary view would you query to check the status of a view based ona table that was dropped?

If errors occur during compilation of objects, the STATUS column in DBA_OBJECTS is set to INVALID. Compiled objects that are available for use are marked VALID. In this example, the view would be marked as INVALID.

Which view would you query to display the value assigned to the MAXDATAFILES parameter for the PROD database?

SQL> select type,records_total from V$CONTROLFILE_RECORD_SECTION;

TYPE RECORDS_TOTAL----------------- -------------DATABASE 1CKPT PROGRESS 4REDO THREAD 4REDO LOG 62DATAFILE 256FILENAME 567TABLESPACE 256RESERVED1 256RESERVED2 1LOG HISTORY 1696OFFLINE RANGE 290ARCHIVED LOG 1603BACKUP SET 305BACKUP PIECE 514BACKUP DATAFILE 526BACKUP REDOLOG 160DATAFILE COPY 512BACKUP CORRUPTION 277COPY CORRUPTION 305DELETED OBJECT 1628PROXY COPY 640

What is the maximum number of control files that you can specify in theCONTROL_FILES parameter?

8

What would you do if your database has two redo log groups and Group 2 becomes corrupted?

Reinitialize the log files in Group 2 with the ALTER DATABASE CLEAR LOGFILE command.You can clear a group if all its members become corrupt by issuing the ALTER DATABASE CLEAR LOGFILE command. This command can be used even if there are only two redo log groups. If you need to clear a redo log group that has not yet been archived, you must include the UNARCHIVED keyword in the command.

How often will a log switch occur if you set the LOG_CHECKPOINT_INTERVAL initialization parameter to 25?

After LGWR writes 25 operating system blocks

You are tuning the PROD database and need to determine the sequence number of the current redo log group. Which view would you query to display the number of online redo log groups?

select SEQUENCE# from v$thread;

You query V$LOGFILE and find that log3a.rdo in group 3 has a status of NULL.What can be said about this file?

It is in use

V$LOGFILE displays each group, each member, and the status of each member. The values of the STATUS column can be: INVALID - inaccessible, STALE - incomplete, DELETED - no longer being used, NULL - in use

What is the advantage of running a database in ARCHIVELOG mode?

Complete recovery is possible even after the redo logs have been overwritten usingthe archived redolog files

Which view would you query to determine if the PROD database is in NOARCHIVELOG mode?

select LOG_MODE from v$database;

If you query V$LOG and find that GROUP 3 is INACTIVE, what can be said about this group?

The group is no longer needed for instance recovery.

How would you drop a redo log member from an active group when archiving is enabled?

After the group is archived, issue the ALTER SYSTEM SWITCH LOGFILE command then the ALTER DATABASE DROP LOGFILE MEMBER command.To drop a redo log member, use the ALTER DATABASE DROP LOGFILE MEMBER command. If the database is in ARCHIVELOG mode, you cannot drop an online member until it has been archived. If the group is active, you must force a log switch before dropping one of its members. You cannot drop the last valid member of a group. Dropping a member does not remove its O/S file.

What will the Oracle Server do if you issue the ALTER DATABASE ADD LOGFILE command without the GROUP option?

The syntax to add a redo log group:

ALTER DATABASE prodADD LOGFILE GROUP 2 ('/disk2/log2a.rdo','/disk3/log3b.rdo') SIZE 1M;

If you specify the GROUP option, you must use an integer value. If you do not use the GROUP option, the Oracle Server will automatically generate a value. Use the SIZE option if you are creating a new file. Use the REUSE option if the file already exists.

When moving datafiles, which function does the ALTER DATABASE RENAME FILE and ALTER TABLESPACE RENAME DATAFILE commands provide?

Reset internal file pointers in the control file.

What is the default value of the PCTINCREASE parameter for a tablespace?

50 (This is very bad, set it to 0)

You created a tablespace with MAXEXTENTS equal to 500. How could you increase the setting?

Use the ALTER TABLESPACE command to change the MINIMUM EXTENTS value or the DEFAULT STORAGE parameters for a tablespace.

When the USER_DATA tablespace was created, you over estimated the amount of space required for the user01.dbf datafile. How would you change the size of the datafile from 100M to 10M?

Use the RESIZE option with the ALTER DATABASE DATAFILE command.

How would you make an offline tablespace read-only?

Issue the ALTER TABLESPACE ONLINE command then the ALTER TABLESPACE READ ONLY command.

When you make a tablespace read-only, all the datafiles must be online and the tablespace can have no pending transactions or active rollback segments. To make a read-write tablespace read-only, use this command: ALTER TABLESPACE tablespace_name READ ONLY; To make a read-only tablespace read-write, use this command: ALTER TABLESPACE tablespace_name READ WRITE;

Evaluate this command:

CREATE TABLESPACE user_dataDATAFILE '/disk2/us_data01.dbf' SIZE 10MMINIMUM EXTENT 500KDEFAULT STORAGE(INITIAL 100K NEXT 100K MAXEXTENTS 500 PCTINCREASE 0);

Why will this statement fail?

INITIAL and NEXT should be a multiple of MINIMUM EXTENT.

When MINIMUM EXTENT is specified, every extent allocated in the tablespace should be a multiple of MINIMUM EXTENT. In this case, NEXT and INITIAL should be multiples of 500K.

DB_BLOCK_SIZE for the PROD database is 2K. You created the USER_DATA01 tablespace without specifying a value for the NEXT parameter. What will be the size of the second extent allocated to the USER_DATA01 tablespace?

The default value of the NEXT parameter is 5 data blocks. In this case, the size of the second extent allocated can be determined by: 5 * DB_BLOCK_SIZE = 10K

When moving datafiles, when would you use the ALTER DATABASE command rather than ALTER TABLESPACE command?

When the tablespace is the SYSTEM tablespace

What would happen if DB_BLOCK_SIZE is 4K and you attempt to createa tablespace with INITIAL equal to 4K?

A syntax error would be returned.

The minimum INITIAL value allowed is: 2 * DB_BLOCK_SIZE

Which two are physical structures and part of an Oracle database?

Datafile and OS-Blocks

The physical structure of a database includes O/S blocks, datafiles,control files, and online redo log files.

Which command would you use to change the size of the minimum extent allocated to the USER_DATA tablespace from 2M to 3M?

ALTER TABLESPACE MINIMUM EXTENT

Use the ALTER TABLESPACE command to change the MINIMUM EXTENT value or the DEFAULT STORAGE parameters for a tablespace.

Evaluate this command:

ALTER TABLESPACE data01 COALESCE;

Which background process performs the same task?

Coalescing merges neighboring free extents. This is automatically done by the SMON background process if the PCTINCREASE value for the tablespace is greater than zero. You can manually coalesce a tablespace by using this command: ALTER TABLESPACE tablespace_name COALESCE;Query DBA_FREE_SPACE_COALESCED to determine if a tablespace needs to be coalesced.

What happens when free space drops below the PCTFREE threshold?

A block is removed from the free list when it falls below the PCTFREE threshold. It is returned to the free list when the used space falls below PCTUSED.

Which type of segment speeds data retrieval while minimizing disk contention?

An index can be partitioned to minimize disk contention while decreasing the amount of time required for queries.

Evaluate this command:

ALTER ROLLBACK SEGMENT rbs01 SHRINK TO 4M;

What would be the result if the current size of RBS01 is 3M?

The command is ignored.

The ALTER ROLLBACK SEGMENT command with the SHRINK option will shrink a rollback segment. If no value is specified, the Oracle Server will attempt to shrink to the OPTIMAL value. To shrink a rollback segment to a specific size, use this command:ALTER ROLLBACK SEGMENT SHRINK TO integer K/M;If the SHRINK TO size or OPTIMAL is greater than the current size of the rollback segment, the command is ignored.

Evaluate this command:

ALTER ROLLBACK SEGMENT rbs01 OFFLINE;

What will happen if RBS01 has pending transactions when the command is issued?

The segment is taken offline when all transactions are complete.

A rollback segment cannot be taken offline if it has pending transactions. If you use the ALTER ROLLBACK SEGMENT command to take it offline before the pending transactions end, the rollback segment will be marked as 'PENDING OFFLINE'. The rollback segment will not be taken offline until the transactions complete.

Which type of segment records changes for multiple transactions?

Rollback segments store the before image when changes are made to data in the database. A transaction can only be assigned to one rollback segment, however a rollback segment can store images for multiple concurrent transactions.

Which type of rollback segment is automatically dropped when it is no longerneeded by the Oracle Server?

The SYSTEM rollback segments record changes made to objects in the SYSTEM tablespace.Private rollback segments are acquired by an instance when they are named in the parameter file.Public rollback segments are in the pool of rollback segments.Deferred rollback segments are created by the Oracle Server when a user attempts to commit a transaction that will change data in a tablespace that is offline. The Oracle Server will drop these segments when they are no longer needed.

Which three methods can you use to decrease the probability of snapshot too old errors?

Use larger extent sizes.Create rollback segments with higher OPTIMAL values.Create rollback segments with high MINEXTENTS values

A snapshot too old error occurs when the Oracle Server cannot create a read consistent image of the data when a query is executed. The error is returned when a query is issued on a row with a lock, but before the query is finished the transaction commits and the rollback segment is overwritten. Reduce the chances of snapshot too old errors by creating rollback segments with high MINEXTENTS values, larger extent sizes, and high OPTIMAL values.

What is the recommended size for MINEXTENTS to reduce the possibilityof rollback segment extension?

20

MINEXTENTS for a rollback segment should be greater than or equal to two. Oracle recommends a value of 20 to reduce the likelihood of extension. OPTIMAL should be greater than or equal to MINEXTENTS. PCTINCREASE cannot be specified and should be set to zero. INITIAL should always be equal to NEXT. All the extents allocated to a rollback segment should be the same size. Place rollback segments in tablespaces that do not contain data to minimize I/O contention and fragment.

Which three steps are necessary before you can take a tablespace offline that contains active rollback segments?

Before you can take a tablespace with active rollback segments offline:

Query DBA_ROLLBACK_SEGS to determine which rollback segments are in the tablespace and take the rollback segments offline.

Query V$TRANSACTIONS to determine the transaction currently using the rollback segments.

Query V$SESSION to determine the user with the pending transaction and terminate their session.

To which size should INITIAL and NEXT be set when defining DEFAULT STORAGE for a TEMPORARY tablespace?

DB_BLOCK_SIZE+(multiple of SORT_AREA_SIZE)

Temporary segments are based on the default storage parameters of the tablespace. For the TEMPORARY tablespace, INITIAL and NEXT should be equal to each other and a multiple of SORT_AREA_SIZE plus DB_BLOCK_SIZE. PCTINCREASE should always be equal to zero.

How are sort segments allocated during a sort in a TEMPORARY tablespace?

Several transactions can simultaneously share the same sort segment.

Why would you query V$SORT_SEGMENT?

To determine the number of extents allocated to a TEMPORARY tablespace containing a sort segment

Which two dynamic performance views could you join to determine the number of extents being used by an active sort?

V$SESSIONV$SORT_USAGE

Join V$SESSION and V$SORT_USAGE to display the username, session address, tablespace, contents, extents, and blocks for active sorts.

Which view could you query to display the Sort Extent Pool status?

V$SORT_SEGMENT

When altering a table, which parameter indicates the number of bytes above the high water mark that the table will have after deallocation?

KEEP

To deallocate all unused space in a table above the high water mark, use this command:

ALTER TABLE table DEALLOCATE UNUSED;

To deallocate unused space while keeping a specified number of bytes above the high water mark, use this command:

ALTER TABLE table DEALLOCATE UNUSED KEEP integer K/M;

If the size specified in the KEEP option is below MINEXTENTS, MINEXTENTS will be kept.

Which command would you issue to release all the space allocated to an empty table,except for MINEXTENTS?

TRUNCATE TABLE DROP STORAGE;

Which function in the DBMS_ROWID package would you use to convert ROWID values into a relative file number?

The ROWID_RELATIVE_FNO function in the DBMS_ROWID package returns the relative file number of the file that stores the row. The ROWID_BLOCK_NUMBER function in the DBMS_ROWID package returns the block number stored in the row in the relative file. The ROWID_ROW_NUMBER function in the DBMS_ROWID package returns the sequence number of a given ROWID value.

Which parameter should you increase to avoid excessive row migration?

Increase PCTFREE

If PCTFREE is set too low, there may not be enough room in the data blocks to update existing rows. When there is insufficient space in the data block, the row is moved to a new data block and the old block stores a pointer to the new location. Row migration slows table scans because two blocks are scanned for one row.

If a column will store 266 bytes, how many bytes will the column length be in the block header?

3 ( 1 for columns length 250 )

When row data is stored in a data block, the column length is recorded as either 1 byte for column lengths 250 bytes or less or 3 bytes for column lengths greater than 250 bytes.

The DESCRIPTION column in the PRODUCT table requires an average of 100 bytes per row . Which datatype could you use as a pointer to the DESCRIPTION column rather than storing this value again in the ORDERS table?

REF

The REF datatype is a relationship type that stores a pointer to the data in another table, rather than storing the actual data.

Evaluate this command:

ANALYZE TABLE orders ESTIMATE STATISTICS;

How many rows will be sampled if the ORDERS table contains 5000 rows?

1064

To detect row migration or chaining in a table, use the ANALYZE TABLE command. The COMPUTE STATISTICS option will return exact statistics because it analyzes all of the rows in the table. The ESTIMATE STATISTICS option will compute statistics based on 1064 rows. You can use the ESTIMATE STATISTICS option with a sample integer or percent to specify the number or percentage of rows that are scanned.

A new table with 100 free blocks has inserts filling 70 blocks followed by deletes freeing 20 blocks. Where is the resulting high water mark at this point?

70 Blocks (INITRANS Index > INITRANS Table)

The high water mark in a table is the last block ever used by the table. The high water mark is not reset when data is deleted. When a full table scan is performed, each block is read up to its high water mark.

You are creating an index for a table and are considering a value for INITRANS for this index. How should INITRANS be set for this index relative to the INITRANS value already set for the corresponding data table?

Higher

Because index entries are small, there are usually more entries per block so the INITRANS value should be higher than the table.

You have a table with an associated index. How is this index affected if the table is truncated?

The TRUNCATE command deletes all the rows in the table and releases all the unused space. The corresponding indexes will also be truncated. If the REUSE option is used with the TRUNCATE command, the data is deleted from the table and its corresponding indexes, but no space is deallocated. If the DROP option is used with the TRUNCATE command, the extents specified by MINEXTENTS are retained. A table cannot be truncated that is referenced by a foreign key.

How does a partitioned index differ from a nonpartitioned index?

Partitioned indexes allow an index to be spread across multiple tablespaces.

Which data dictionary view would you query to determine if an index is VALID?

DBA_INDEXES

Where do the parallel query slaves insert data when a parallel direct-load insert is performed?

To perform a parallel direct-load insert, use the PARALLEL hint in the INSERT INTO SELECT command. The parallel direct-load insert uses parallel query slaves to insert the data. The data is written to temporary segments until the transaction commits.

You have exported a file for subsequent import into another tablespace. In which sequence is the Import file loaded?

The order of import:

1. table definitions2. table data3. indexes on the table4. integrity constraints, triggers, and bitmap indexes

Which SQL*Loader parameter specifies the number of logical records to load?

The LOAD parameter in the SQL*Loader command specifies the number of records to load. This value does not include any records that are skipped.

For which two reasons would you use direct-load inserts when loading data into a table?

Other rows in the same table can be concurrently modified by other users.Data can be quickly copied from one table into another within the same database because itbypasses the buffer cache.

Use the INSERT INTO SELECT command to perform a direct-load insert. This command can be used to copy data from one table to another table in the same database. The buffer cache is bypassed to speed up the insert. During a direct-load insert, users can be concurrently modifying existing data in the table. Data is loaded above the high water mark.

Which user needs a usage quota?

The QUOTA clause defines the amount of space in bytes that a user can use to create and maintain objects in a specified tablespace. The default value is no space and the maximum value is UNLIMITED.

Evaluate this command:

ALTER USER bill QUOTA 0 ON data01;

If a 20M table exists in the DATA01 tablespace owned by user BILL, which effectwill this command have ?

The objects created by user BILL in the DATA01 tablespace will remain, but no new extents can be allocated to the objects.

Which data dictionary view could a user query to display the number of bytes charged to their username?

USER_TS_QUOTAS

USER_TS_QUOTAS displays the names of tablespaces that the user has a QUOTA on, the number of bytes and blocks used, and the maximum number of bytes and blocks allowed.

Which four resource limits are averaged by specified weighting to give a composite limit?

When assigning a COMPOSITE_LIMIT to a profile, Oracle calculates a weighted sum for these resource limits:PRIVATE_SGACPU_PER_SESSIONCONNECT_TIMELOGICAL_READS_PER_SESSIONTo specify the weights assigned to each limit, use the ALTER RESOURCE COST command.

Evaluate this statement:

ALTER PROFILE juan LIMITCPU_PER_SESSION 3600 (1/100 Sec)IDLE_TIME 30; (Min)

How much time will be allowed in the next session for user JUAN?

36 seconds of cpu time and 30 minutes of inactivity

CPU_PER_SESSION is expressed in hundredths of seconds and IDLE_TIME is expressed in minutes

You ran the script to create the VERIFY_FUNCTION function and it altered the DEFAULT profile.

After the VERIFY_FUNCTION is enabled and the DEFAULT profile is altered, a user must change their password using these guidelines:1. The new password must differ from the old password by more than three characters.2. The password must have at least 4 characters.3. The password cannot be equal to the username.4. The password must have at least one alpha, one numeric, and one special character.

Which initialization parameter would you alter to disable the enforcement of resource limits?

To disable resource limits, set the RESOURCE_LIMIT parameter to FALSE. To enable the enforcement of resource limits for the current instance, use the ALTER SYSTEM command to set the RESOURCE_LIMIT initialization parameter to TRUE. To enable or disable the enforcement of resource limits for future sessions, alter the RESOURCE_LIMIT initialization parameter in the parameter file.

Which view would you query to display information about password expiration, locking dates, and account status for user CHAN?

DBA_USERS

You are administering password settings for a profile. Which parameter ensures that a user does not reuse the same password?

When the PASSWORD_MAX_REUSE parameter is set to UNLIMITED, a user can never reuse the same password.

Which object privilege do you need to grant privileges on an object not in your schema?

Object privileges are granted WITH GRANT OPTION. When object privileges are revoked, the revoke cascades.

Which system privilege do you need to grant a system privilege to another user?

System privileges are granted WITH ADMIN OPTION. When system privileges are revoked, the revoke does not cascade.

Which privilege is required to TRUNCATE a table owned by another user?

DROP ANY TABLE

Which command could you use to set a default role for a user?

To define a default role for a user, you must grant the role to the user with the GRANT command. By default, all the roles granted to the user will be enabled when the user connects unless the ALTER USER DEFAULT ROLE command is used to limit the default roles.

Evaluate this command:

ALTER USER jenniferDEFAULT ROLE ALL;

Which task would this accomplish?

Set all roles as default for user JENNIFER

Which three functions can be used with the NLS_SORT parameter?

The NLS_SORT parameter can be used with the NLS_UPPER, NLS_LOWER, NLS_INITCAP, and NLSSORT functions.

NLS Views

NLS_SESSION_PARAMETERS: This View lists NLS parameters of the user session.NLS_DATABASE_PARAMETERS: This View lists permanent NLS parameters of the databaseNLS_INSTANCE_PARAMETERS: This View lists NLS parameters of the instance.

SQL> select * from nls_session_parameters;

PARAMETER VALUE------------------------------ ------------------------------NLS_LANGUAGE AMERICANNLS_TERRITORY AMERICANLS_CURRENCY $NLS_ISO_CURRENCY AMERICANLS_NUMERIC_CHARACTERS .,NLS_CALENDAR GREGORIANNLS_DATE_FORMAT DD-MON-YYNLS_DATE_LANGUAGE AMERICANNLS_SORT BINARYNLS_TIME_FORMAT HH.MI.SSXFF AMNLS_TIMESTAMP_FORMAT DD-MON-YY HH.MI.SSXFF AMNLS_TIME_TZ_FORMAT HH.MI.SSXFF AM TZH:TZMNLS_TIMESTAMP_TZ_FORMAT DD-MON-YY HH.MI.SSXFF AM TZH:TNLS_DUAL_CURRENCY $NLS_COMP

SQL> select * from nls_database_parameters;

PARAMETER VALUE------------------------------ ------------------------------NLS_LANGUAGE AMERICANNLS_TERRITORY AMERICANLS_CURRENCY $NLS_ISO_CURRENCY AMERICANLS_NUMERIC_CHARACTERS .,NLS_CHARACTERSET WE8ISO8859P1NLS_CALENDAR GREGORIANNLS_DATE_FORMAT DD-MON-YYNLS_DATE_LANGUAGE AMERICANNLS_SORT BINARYNLS_TIME_FORMAT HH.MI.SSXFF AMNLS_TIMESTAMP_FORMAT DD-MON-YY HH.MI.SSXFF AMNLS_TIME_TZ_FORMAT HH.MI.SSXFF AM TZH:TZMNLS_TIMESTAMP_TZ_FORMAT DD-MON-YY HH.MI.SSXFF AM TZH:TNLS_DUAL_CURRENCY $NLS_COMPNLS_NCHAR_CHARACTERSET WE8ISO8859P1NLS_RDBMS_VERSION 8.1.5.0.0

Oracle-8 Database Tuning

Which TKPROF option should you set to ignore recursive SQL ?

SYS Option

At which level does Oracle resolve deadlocks ?

Statement Level

What is an effect of setting the CACHE_SIZE_THRESHOLD parameter?

Limits the number of blocks cached for each table.

You discover excessive I/O to datafiles in the SYSTEM tablespace duringnormal operations. What are three likely causes for this problem?

- The Shared Pool is too small- Data Segments are being written to the SYSTEM tablespace- Sort Segments are being written to the SYSTEM tablespace

Which factor is most important in determining the OPTIMAL size for a rollback segment?

Transaction activity of the database during normal processing.

Which command would you use to reset the high-water mark on a table?

TRUNCATE

Given this formula:

number of blocks that contain rows 100 * ----------------------------------------------------- number of blocks below the high-water mark

For non-empty tables, which value should be your target?

100

Your operating system does not support striping. Striping by hand is a very time-consuming task. Which two conditions might make striping by hand worthwhile?

- The database is using Parallel Query Option- The application is performing many full table scans.

Which view can be queried to check the amount of sharable memory used by a cached object?

desc v$db_object_cache;

Name Null? Type------------------------------- -------- ----OWNER VARCHAR2(64)NAME VARCHAR2(1000)DB_LINK VARCHAR2(64)NAMESPACE VARCHAR2(15)TYPE VARCHAR2(24)SHARABLE_MEM NUMBERLOADS NUMBEREXECUTIONS NUMBERLOCKS NUMBERPINS NUMBERKEPT VARCHAR2(3)

Your database is installed on a multi-CPU system. If the Utlbstat/Utlestat utility shows contention for the redo copy latch, which action should you take?

Increase the value of the LOG_SIMULTANEOUS_COPIES parameter. This Parameter specifies the number of redo buffer copy latches. For Single CPU Machines set it to 0, for Multi CPU Machines set it to 2 x Number of CPUs.

Your system has limited physical memory. You have an application that uses many large sorts. Which parameter can be set to improve the performance of these large sorts?

SORT_DIRECT_WRITES = True/False/Auto (Bypass Buffer Cache)

Set it to True if there is abundant memory. This parameter controls whether sort data will bypass the buffer cache to write intermediate sort to disk.

You query the V$LIBRARYCACHE view to determine the Reloads-to-Pins ratio.What is the ideal value for the SUM of the RELOADS for a database?

0

Which command would you use to organize space within an existing index?

ALTER INDEX REBUILD ...

In which two files will deadlock contention be recorded?

Alert Log FileUser Process Trace File

Which two steps are necessary to evaluate the impact of reducing the buffer size?

Query the V$RECENT_BUCKET viewSet the Parameter DB_BLOCK_LRU_STATISTICS to TRUE

Which two views could you query to determine lock contention on the EMP table?

V$LOCK (Lock currently held by the Oracle Server)V$LOCKED_OBJECT (Lists all locks acuired by every transaction on the system)

A user complains that an exceptionally large update fails. What are the two most likelycauses of this problem?

MAXEXTENTS has been set too lowTablespace for Rollback Segments too small

What is an effect of setting the CACHE_SIZE_THRESHOLD parameter?

Limits the number of blocks cached for each table

You check the init.ora file and see that LOG_SIMULTANEOUS_COPIES = 2 for your fourCPU machine. It is recommended that you set this parameter to which value if you see contention?

8 (Good Performance set it to 2 x Number of CPU's)

Your system has abundant physical memory. You have an application that uses many large sorts.Which two parameters can be set to improve the performance of these large sorts?

SORT_AREA_SIZE= (Increasing the size improves the efficiency of large sorts)SORT_DIRECT_SORTS=TRUE (Can improve sort performance for abundant memory)

Which dynamic performance view would you query to display the total waitsfor "buffer busy waits" since instance startup?

V$SYSTEM_EVENT (Total Waits on en event since Instance startup)

What should you do if the hits on the LRU latch are less than 1% and yoursystem has multiple CPUs?

Modify the DB_BLOCK_LRU_LATCHES parameter

In a joint effort with the system administrator to tune the system, you gather information about the database. Which view can be queried to provide statistics for tuning I/O?

V$FILESTAT (I/O Statistics, V$LOADSTAT ist for SQL*Loader)

Which statistics can be obtained by querying the V$SYSSTAT view?

Redo Log Buffer, select CLASS = 2

What will result in a very low value for the TKPROF Disk statistic?

Buffered Data

When tuning SQL, which mechanism will provide an efficient method for joining two tables when one table is significantly larger than the other?

Hash Join

You have an eight CPU machine. Which step would you take to increase performance on tables with a high number of concurrent inserts?

Recreate the table increasing the number of freelists.

Your database is installed on a multi-CPU system. If the Utlbstat/Utlestat utilities show contention for the redo copy latch, which action should you take?

Increase the value of the LOG_SIMULTANEOUS_COPIES parameter.

What does the MAX_DUMP_FILE_SIZE parameter limit?

The MAX_DUMP_FILE_SIZE parameter value is specified in O/S blocks and specifically limits the size of user trace files.

Which information does the V$EVENT_VIEW view provide?

The V$EVENT_NAME view lists all event names and their associated parameters.

SQL> select event#, substr(name,1,50) from v$event_name where rownum < 10;EVENT# SUBSTR(NAME,1,50)--------- ---------------------------------------------0 Null event1 latch activity2 latch free3 free process state object4 pmon timer5 inactive session

Which view can you query to find information about system-wide waits per session?

V$SESSION_EVENTS

You query the V$SYSTEM_EVENT view with this command:

SELECT event, total_waits, total_timeouts,time_waited, average_waitFROM v$system_event;

Which event would indicate contention in the database buffer cache?

Buffer Busy Waits

For which reason should you enable tracing for a user session?

A user has complained about the time it is taking to execute an application process.

You query V$SESSION_WAIT and see a wait time of 2 for an event.Which information does this query provide?

Active session's last wait time

Which view can you query to see the total number of event waits since instance startup?

V$SYSTEM_EVENT

You have run the UTLBSTAT/UTLESTAT utilities and the report.txt shows a latch hit ratio of 0.99. What does this value indicate about latch activity for the database?

A latch hit ratio of 99% is optimal. Latch contention should be always be 1% or less. To resolve redo latch contention, increase LOG_SIMULTANEOUS_COPIES and decrease LOG_SMALL_ENTRY_MAX_SIZE.

When viewing latch statistics in the report.txt, with which column should you be most concerned?

HIT_RATIO

Which view will provide basic instance statistics?

The V$SYSSTAT view provides basic instance statistics cumulated since instance start up.

Which view could be queried to determine the type of user connection?

SELECT sid, username, type, serverFROM v$session;SELECT sid, username, type, server FROM v$session;SID USERNAME TYPE SERVER--------- ------------------------------ ---------- ---------1 BACKGROUND DEDICATED

You have a hybrid system processing reports at night. What can you do to handle heavy transaction processing during the day and report processing at night?

Use many small rollback segments during the day and fewer large rollback segments at night.The segments not being used for reporting should remain offline until they are needed.

Using a hybrid system, OLTP for day and DSS for night, what is the most efficient method of altering the parameters for day and night use?

Reset the parameters for day and night using a separate pfile.

What can you use to identify SQL areas that are possibly causing performance problems?

SQL Trace can be set at instance or session level and provides detailed information regarding the execution of a SQL statement.

When creating queries, which keyword will create a sort and incur I/O and processing overhead?

When DISTINCT is used, the data is sorted. If the statement selects a large number of rows, the server may generate temporary segments to handle the sort runs. This process incurs I/O and processing overhead, and should be avoided.

What can be used to join two tables when one is significantly larger than the other?

Hash Join

Which information is stored in the lookup tables used in star queries?

Information about entries for attributes in the fact table. Lookup tables are small tables joined to the fact table using a PK-FK join.

Which two things can you track using the DBMS_APPLICATION_INFO package?

Performance and Resource Usage

DBMS_APPLICATION_INFO contains procedures needed to register and then track a module. When an application calls these procedures, they record and read information into and from the V$SESSION and V$SQLAREA views.

Which clause can increase response time if not used properly in an SQL statement?

Statements including group functions impact performance. Use a WHERE clause to exclude unwanted rows. HAVING should only be used with an aggregate condition. Inappropriate use of the HAVING clause increases response time.

Which two procedures within the DBMS_APPLICATION_INFO package can be used to track module performance?

READ_MODULE reads the last module and action names set by SET_ACTION or SET_MODULE. READ_CLIENT_INFO reads the last client information set for the session.

Which two parameters, when set, have a negative impact on CPU performance?

DB_BLOCK_CHECKSUMLOG_BLOCK_CHECKSUM

Which init.ora parameter, when set to TRUE, will cause Oracle to bring all SGA pages into memory when the instance is started?

PRE_PAGE_SGA

Instance start up time is increased using this parameter, but it can reduce the number of page faults that occur. The reduction in page faults allows the instance to reach its maximum performance capability more quickly

What does the RELOADS column of the V$LIBRARYCACHE view represent?

The number of object definitions that have been aged out of the library cache for lack of space.

Which information does the PINS column of the V$LIBRARYCACHE view represent?

The number of executions of SQL statements or procedures in the library cache.

Which two views can be queried to gather information about UGA space usage for all MTS users?

V$SESSTATV$STATNAME

SELECT SUM(value) || 'bytes' "Total session memory" FROM v$sesstat, v$statnameWHERE name = 'session uga memory' AND v$sesstat.statistic# = v$statname.statistic#;

Which objects should you consider keeping in the shared pool?

Pinning sequences in the shared pool will prevent the numbers from being lost, which is normal when they are aged out.

Which view can you query to determine the amount of sharable memory used by acached PL/SQL object ?

SELECT SUM(sharable_mem)FROM v$db_object_cacheWHERE type = 'PACKAGE' OR type = 'PACKAGE BODY' ORtype = 'FUNCTION' OR type = 'PROCEDURE';

What is the recommended number of bytes to allow in the shared pool per user per open cursor?

Oracle recommends allowing about 250 bytes in the shared pool per user per open cursor. This can be tested during peak times using this query:

SELECT SUM(250 * users_opening)FROM v$sqlarea;

Due to operating system memory limitations, you need to set the SHARED_POOL_RESERVED_SIZE. Which additional parameter should you also increase by the same amount?

SHARED_POOL_SIZE

Which parameter is used to determine the number of blocks for multiple buffer pools?

DB_BLOCK_BUFFERS

Determine the size of each buffer pool by subtracting the number of buffers for each buffer pool from the total number of buffers defined for the entire buffer cache. If this constraint is violated, the database will not mount.

What is affected by the value of DB_BLOCK_BUFFERS?

The buffer cache holds copies of the data blocks from the datafiles. The DB_BLOCK_BUFFERS parameter specifies the number of blocks in the buffer cache.

What can you code into your queries to store the data blocks in the buffer cache?

Cache Hint Clause: Using this method causes the Oracle server to place the table blocks at the most recently used end of the LRU list.

Which two can you query to evaluate the effect of an increase or decrease to the size of the database buffer cache? (Tuning Buffer Cache).

V$SYSSTATV$RECENT_BUCKET

Which information about the database buffer cache is obtained by querying V$RECENT_BUCKET?

Number of additional cache hits gained by adding additional buffer cache blocks

Which information can be used to size the RECYCLE pool?

Total number of buffer cache blocks used by each object. The RECYCLE buffer pool should be large enough to be retained for the duration of the transaction.

What should be your tuning goal when sizing the KEEP buffer pool?

Retain as many objects in memory as you can.

When are dirty blocks flushed from the data buffer cache?

When the server process is searching the LRU list, DBWR managers the buffer cache by writing dirty blocks to the datafiles to ensure that there are free blocks for servers.

- When Dirty List exceeds threshold- Independent of COMMIT- No more free Blocks in LRU-List

When will DBWR write dirty blocks to the datafiles?

when the dirty list exceeds its size threshold

The database is using the Oracle Parallel Server option. Which view can you query to analyze the database buffer cache?

V$CACHE is created with the catparr.sql script. It can be viewed to monitor the number of buffer pool blocks by object and is intended for use with Oracle Parallel Server.

You can create the V$CACHE view which is useful for Oracle Parallel Server. Which information can be queried with this view?

Objects currently being cached

Which two copies of a single database block can be found in the database buffer cache at all times?

- Current block- Read consistent block for rollback

The buffer cache may hold multiple copies of a single database block. Only one current copy exists, but server processes may need to reconstruct read-consistent copies using rollback information.

What is the minimum number of buffers that must be allocated to each buffer pool ?

50 times the number of LRU latches

You have been monitoring buffer cache performance and see that the values have been increasing for 'free buffer inspected'. What does an increase in this value indicate?

Number of buffers skipped to find a free buffer.

You view the alert.log and see this error:

"Checkpoint not complete; unable to allocate file"

What does this indicate?

LGWR has waited for DBWR to finish.

Which resource is used when a process writes changes to the redo log buffer?

The redo allocation latch controls the allocation of space for redo entries in the redo log buffer. There is only one redo allocation latch.

When does a process release the redo allocation latch on a single CPU machine?

When the process copies the entry into the buffer, there is only one redo allocation latch per instance. The number of CPU's only has an effect on redo copy latches.

The V$SYSTEM_EVENT view indicates there have been waits for the event 'log buffer space'.What does this indicate?

The LOG_BUFFER parameter needs to be increased.

You have two redo log groups, with two members each. Which two events will occur when a redo log group fills in an archived database?

A checkpoint occurs.One member of the log group will be archived.

In which tablespace should you place stored packages and database triggers?

Stored objects such as database triggers and packages are part of the data dictionary and should be stored in the SYSTEM tablespace.

What is one method of striping tablespaces by hand?

To allocate extents explicitly, use this command:

ALTER TABLE tablenameALLOCATE EXTENT (DATAFILE 'filename' SIZE sizeM);

Where are temporary segments created in a default user setup?

If you do not explicitly set the temporary tablespace during user creation, sorts occur in the SYSTEM tablespace.

Which two parameters control the use of asynchronous I/O?

DISK_ASYNCH_IOTAPE_ASYNCH_IO

The Reservations application has many volatile tables with indexes. What should be your tuning goal for indexes of this type?

Indexes on volatile tables can present a performance problem and should be monitored and rebuilt frequently.

What is one disadvantage of using large extents?

Having enough contiguous storage space

You issue this statement:

DELETE * FROM parts;

What will be the state of the high-water mark for the PARTS table after this statement has completed?

not changed, DELETE statements have no effect on the high water mark. The TRUNCATE statement must be issued to reset the high water mark.

Which command can be used to monitor the space used by indexes?

ANALYZE INDEX index_name VALIDATE STRUCTURE;

You issued the ANALYZE command against the ITEM table and detected row migration. Which storage parameter should you increase to prevent further chaining to this table?

PCTFREE

Migration is caused by PCTFREE being set too low; there is not enough room in the block for updates. All tables that are updated should have PCTFREE set to allow enough space within the block for updates.

When creating large extents, what should you use as the basis for size?

multiple of 5 * DB_FILE_MULTIBLOCK_READ_COUNT

Multiply by five, because Oracle tries to allocate blocks on five block boundaries.

What does Oracle do with empty index blocks?

If you delete all entries for an index block, Oracle puts the block back on the free list.

You issue this command:

ANALYZE TABLE inventory.item COMPUTE STATISTICS;

Which column of the DBA_TABLES view can you query to see the number of migrated rows in the inventory.item table?

CHAIN_CNT

What is the result of increasing PCTUSED on a table which undergoes numerous deletes?

location of future inserts is changed

PCTUSED is relevant in tables that undergo (=erleiden) deletes, but you may be able to pack rows into blocks more tightly by setting PCTUSED to a value higher than the default of 40%.

FORMULA : PCTUSED = 100 - PCTFREE -100 * (upd-ins)/blocksizewhere upd is the average amount added by updates in bytes and ins is the average initial row length at insert.

An active process needs sort space. Where will it look for the space it needs toperform a temporary sort?

The Sort Extent Pool (SEP) is located in the SGA. When a process needs sort space, it looks for free extents in the SEP.

Which parameter can you set to control sort writes to the buffer cache?

SORT_DIRECT_WRITES

The amount you allocate to direct write buffers should be less than one-tenth (< 1/10) of SORT_AREA_SIZE when SORT_DIRECT_WRITES is set to TRUE.

Which V$SORT_SEGMENT column could you query to see the number of times an unused extent was found in the Sort Extent Pool?

EXTENT_HITS

You query the V$WAITSTAT view and see a value of 5 in the CLASS column for 'undo header'. Which problem does this indicate?

Contention for rollback segment header blocks

The number of waits for any class should be less than 1% of the total number of requests.

In which situation would it be beneficial for you to use the SET TRANSACTION USE ROLLBACK SEGMENT ; command?

Running a large batch job

Which information is stored in rollback segments?

Before images of changed data

To which value should you assign MINEXTENTS when creating rollback segments?

Setting MINEXTENTS to 20 makes it unlikely that the rollback segment needs to obtain another extent due to the current extent being used by an active transaction.

A transaction occurs periodically and you want to define a rollback segment to be assigned to this transaction. Which two views can you query to get the details for a specific user transaction?

Querying V$SESSION and V$TRANSACTION

SELECT a.username, b.used_ublk,b.start_timeFROM v$transaction b, v$session aWHERE b.addr = a.saddr;

In which file can you locate the rowid of the locking row in a deadlock?

A trace file is generated for a deadlock situation and recorded in the USER_DUMP_DEST directory. The value for this directory is recorded in the init.ora.

A deadlock has occurred. What will have to be rolled back?

Transaction detecting the deadlock

Oracle will automatically roll back the statement that detects the deadlock. The remainder of the transaction will have to be manually rolled back. Oracle rolls back the statement and returns an ORA-00060, 'deadlock detected while waiting for resource' error. The transaction is not rolled back and you should roll back the remainder of the transaction, if necessary.

A deadlock occurs in Statement B of a large transaction. What is the state of the transaction?

Statement B is rolled back and an error message is generated for the transaction.

Where are free lists maintained?

Free lists are maintained in the segment header. To increase the number of free lists for an object, you must drop and recreate it using a higher value for the FREELISTS keyword.

Which two views can you query to determine if contention for the free list is high?

V$WAITSTATV$SYSTEM_EVENT

Which information can be obtained from the SLEEPS column of the V$LATCH view?

Number of times a process waited for a latch. Ideally, the percentage of time for which there is latch contention should be less than 1%.

You know that users perform many inserts and deletes to the Order Entry application. What should you identify and monitor to diagnose free list contention in this type of system?

Tables with a high number of inserts. When an insert operation occurs, the free list is used to determine the availability of blocks for inserts. Server processes can contend for the same free list if many inserts are occurring

Which two situations will cause blocks to go to the head of the free list?

The high water mark has changed.Server processes delete rows and space falls below PCTUSED.

The utlestat.sql generates these hit ratios:

LATCH1 1LATCH2 0.98LATCH3 0.75 run2> allocate channel d1 type disk;3> format = 'tue-%s_%p.bck';4> backup incremental level = 0 (database);

Which type of backup will be performed by this command?

Full database backup

Which view would you query to list the number of corrupt blocks in the datafiles for the USER_01 tablespace?

V$BACKUP_DATAFILE

V$BACKUP_DATAFILE will display the number of corrupt blocks found in each datafile during a backup taken with RMAN.

Why would you query V$SESSION_WAIT when a backup is in progress?

When a backup is not progressing, you can query V$SESSION_WAIT to see if any of the backup events have caused the backup to hang.

Why would you query V$BACKUP_CORRUPTION?

Only RMAN will find corrupt blocks during a backup. To list the corrupt blocks found during a backup set, query V$BACKUP_CORRUPTION. To list the corrupt blocks found during an image copy, query V$COPY_CORRUPTION.

You decide to create a script file to inform Recovery Manager of the recent deletion of the user_data2.dbf datafile. Which commands must exist in this file?

$ rman TARGET \"system/manager@prod\" \ RCVCAT \"system/manager@prodrec\" ALLOCATE CHANNEL FOR DELETE TYPE DISK; CHANGE DATAFILECOPY 'user02.dbf' DELETE; RELEASE CHANNEL;

A disk drive has been damaged that contains the user_data9.dbf datafile. Which Recovery Manager command will mark this datafile as unavailable?

CHANGE DATAFILECOPY 'user_data9.dbf' UNAVAILABLE;

Examine these commands:

$ rman TARGET \"system/manager@ora8prod\" \> RCVCAT \"system/manager@prodrec\"

After issuing the commands, you create a full backup of the ORA8PROD database. Which command must you execute to close the connection to the sequential I/O device in Recovery Manager after the backup is complete?

RELEASE CHANNEL channel_id

With Oracle Server Release 7.3, the deferred transaction recovery features allows for faster instance recovery. When are uncommitted transactions rolled back with this feature?

When a request for this data is made by a user

You are going to perform a full database recovery in parallel. The database files are spread across 10 disk drives on your system. When you issue the PARALLEL (DEGREE DEFAULT) clause in the RECOVER command, how many recovery processes per datafile will be assigned?

2

Why is it mandatory for database files be synchronized at all times?

The database cannot be opened if the file synchronization information does not match.

Examine these recovery catalog details:

username: RCATMANpassword: RCATMANconnect string: RCVCAT

Which command will connect to this recovery catalog?

$ rman rcvcat rcatman/rcatman@RCVCATrman> connect target

At approximately 7:00am today, the DEPARTMENT table was accidentally dropped. The database structure has not changed since last Friday and you decide to perform an incomplete database recovery through 6:45am today. Using Recovery Manager, which RUN command clause will perform this recovery?

SET UNTIL TIME = '1998-06-08:06:45:00'

You removed the archived log file named arch_232.rdo located in the '/disk2/archive' directory using an operating system utility. You are using a recovery catalog. Which Recovery Manager command should you issue to inform the recovery catalog to no longer reference this file?

CHANGE ARCHIVELOG '/disk2/archive/arch_232.rdo' UNCATALOG;

A user informs you that they are receiving this error message:

ORA-00376: file 4 cannot be read at this timeORA-00110: data file 4: '/disk2/data/user123.dbf'

Disk 1 is corrupt and the user123.dbf file, uniquely identified by 4, must be moved to a different disk, Disk 5. Using the RUN command in Recovery Manager, which must be issued to inform the database of the new location?

SET NEWNAME FOR DATAFILE 4 TO 'disk5/data/user123.dbf';

Saturday is the start of your weekly backup strategy and a level 0 backup is performed. For subsequent daily backups throughout the week, you only want to back up those blocks that have changed since the previous day's backup. Which RUN command will you use?

rman> run { allocate channel c1 type disk format = '/disk1/backup/tue_%s_%p.bck'; backup incremental level = 1 (database); }

For which reason would you have to consider performing an incomplete recovery?

Redo log files were not mirrored and you lost a redo log file before it was archived.

How is PL/SQL used in Recovery Manager?

Communication interface with the server

In which state must the target database be in for the recovery catalog to acquire rollback segment information?

The database must be OPEN

Which new Oracle8 data dictionary view contains information about archived logs inbackup sets from the control file?

V$BACKUP_REDOLOG

Why would you assign a tag to a backup set?

Provide a useful method to refer to a backup set.

For which reason will you use backup sets in Oracle8?

collectively hold all datafiles and control files

Evaluate this command:

CHANGE DATAFILECOPY 'query_data12.dbf' DELETE;

Why would you issue this command?

Inform Recovery Manager that the query_data12.dbf has been droppedfrom the target database.

Evaluate this Recovery Manager command:

CHANGE DATAFILECOPY 'user_data8.dbf' UNAVAILABLE

Why would you issue this command?

Mark the user_data8.dbf datafile as unavailable.

Evaluate this Recovery Manager command:

LIST BACKUPSET OF DATAFILE "user_data7.dbf";

Why would you issue this command?

Determine the backup for USER_DATA7.DBF.

Why would you use the CMDFILE command within Recovery Manager?

Specify the name of a file that contains additional input commands.

A user informs you that they are unable to query the EMPLOYEE table. The table is stored in a tablespace that contains the 'query_data13.dbf' file that is offline. While investigating, you notice that the drive that contains this file has been damaged. Which command should you issue in Recovery Manager to mark this datafile as unavailable?

CHANGE DATAFILECOPY 'query_data.dbf' UNAVAILABLE;

The files index_data12.bck and arch_423.log have been created and must be added to the recovery catalog. Which set of commands should you execute in Recovery Manager to accomplish this task?

rman> CATALOG DATAFILECOPY "index_data12.bck";rman> CATALOG ARCHIVELOG "arch_423.log";

Evaluate this Recovery Manager script:

$ rman TARGET \"system/manager@prod\" \RCVCAT \"system/manager@prodrec\"rman> ALLOCATE CHANNEL FOR DELETE TYPE DISK;rman> CHANGE DATAFILECOPY 'finance1.dbf' DELETE;rman> RELEASE CHANNEL;

Inform Recovery Manager of the recent deletion of the finance1.dbf datafile.

The INDEX_DATA tablespace has little space and an additional datafile was added to it. Which command should you issue in Recovery Manager?

RESYNC CATALOG;

Evaluate this command issued in Recovery Manager:

REPORT NEED BACKUP DAYS 4;

Why would you issue this command?

A listing of datafiles that have not been backed up within the last four days is required.

Evaluate this command:

DROP ROLLBACK SEGMENT RBS01;

You are using Recovery Manager to facilitate the backup and restore operations. After executing this command, what must you do to the recovery catalog?

Resynchronize it.

The finance2.dbf datafile was manually deleted, instead of using the Recovery Manager DELETE command. Which command should you execute in Recovery Manager?

rman> CHANGE DATAFILECOPY 'finance2.dbf' UNCATALOG

Evaluate these commands issued in Recovery Manager:

rman> CATALOG DATAFILECOPY "user_data6.bck";rman> CATALOG ARCHIVELOG "arch_344.log";

Register these files in the recovery catalog.

After which task(s) will you issue the RESET DATABASE command in Recovery Manager?

point-in-time recovery

Evaluate this code:

rman TARGET \"scott/tiger@v80prod\" \RCVCAT \"scott/tiger@v80prec\" \

Adding which command will create a list of all commands executed during the operation saved to a file called rmnv80prd.log?

MSGLOG \"scott/tiger@rmnv80prd.log\" \

Evaluate this Recovery Manager command:

CHANGE DATAFILECOPY 'user_data8.dbf' DELETE;

When is the actual file deleted from the operating system?

immediately upon execution of this command

Which parameter in the REPORT NEED BACKUP command specifies the minimum number of backups for each datafile to be considered not in need of a backup?

REDUNDANCY

You include this command in a script:

rman> CHANGE DATAFILECOPY 'finance4.dbf' DELETE;

Which command must precede this delete operation?

ALLOCATE CHANNEL FOR DELETE;

Scott added the file user04.dbf to the USER_DATA tablespace in the PROD database. The recovery catalog is called rcatprod. After which task(s) will you issue the RESYNC CATALOG command in Recovery Manager?

Adding a datafile to a tablespace

Evaluate this command issued in Recovery Manager:

RESYNC CATALOG FROM BACKUP control file 'prodbu.ctl';

Why would you issue this command?

A datafile has been added to the target database and the current control files are damaged and unusable.

Evaluate this command issued in Recovery Manager:

REPORT NEED BACKUP DAYS 4 REDUNDANCY 2;

Why would you issue this command?

A listing of datafiles that have not been backed up within the last four days anddo not have at least two backups.

You successfully repaired the device that contains the finance2.dbf datafile. Currently, this file is marked as unavailable in Recovery Manager. Which set of commands should you execute to mark this file as available?

$ rman TARGET \"system/manager@prod\" \RCVCAT \"system/manager@prodrec\"rman> CHANGE DATAFILECOPY 'finance2.dbf' AVAILABLE;

Using Recovery Manager to facilitate your backup and recovery operations, you require a listing of datafiles that have not been backed up within the last six days. Which Recovery Manager command will you issue?

REPORT NEED BACKUP DAYS 6;

Examine these commands:

$ rman TARGET \"system/manager@prod\" \RCVCAT \"system/manager@prodrec\"

After issuing the commands, you create a full archive log backup. Which script will create this backup for these specifications?

Number of archive log files to backup: 320Number of backup sets: 4Delete input files? yesChannel: t1

rman> CREATE SCRIPT PROD_BACK_ARCH (ALLOCATE CHANNEL t1 NAME "sbt_tape"; BACKUP FULL FILESPERSET 80 (ARCHIVELOG ALL DELETE INPUT FORMAT "PRODARCH.%s.%p"); RELEASE CHANNEL t1);

The files user_data8.bck and arch_112.log have been created and now must be added to the recovery catalog. Which set of commands must you execute in Recovery Manager to accomplish this task?

CATALOG DATAFILECOPY "user_data8.bck";CATALOG ARCHIVELOG "arch_112.log";

Evaluate these commands:

$ rman TARGET \"system/manager@prod\" \> RCVCAT \"system/manager@prodrec\"> SETLIMIT CHANNEL KBYTES 500;

Which statement describes the purpose of executing these commands?

Each backup piece must be no larger than 500K.

Which object is a single output file in a backup set?

Backup Piece

Examine this RMAN command:

rman> run2> allocate channel d1 type disk;3> allocate channel d2 type disk;4> copy #2 files copied in parallel5> datafile 1 to '/backup/file1.dbf',6> datafile 2 to '/backup/file2.dbf';

This command creates two channels to write to disk. The COPY command uses the two channels to copy the two datafiles at the same time.

What happens when the Oracle Server encounters a fractured block during a backup operation?

Re-reads the block, a fragmented block is a block that is being written to as it is being read by the backup utility. The backup utility will re-read the blocks.

Which type of RMAN backup would you use if you need to include all the blocks and check for block corruption?

Image copy

RMAN supports an image copy backup and a backup set. An image copy backup is similar to an operating system backup. It will copy all of the blocks and check for block corruption. A backup set only copies used blocks.

Examine this RMAN command:

rman> run {allocate channel d1 type disk;copy level 0datafile 1 to 'backup/file1.dbf',datafile 2 to 'backup/file2.dbf';}

How do you know that this copy will be used in an incremental backup set?

Level 0 was used with the COPY command.

This command creates one channel and writes two datafiles to disk. It performs a level 0 incremental backup that can be used as a base for incremental backups.

When you allocate a channel in RMAN, what does the number of channels indicateduring a backup operation?

The degree of parallelization available during the backup

For each channel allocated by an RMAN RUN command, an Oracle Server process is created. The number of channels allocated determines the maximum degree of parallelization available for the backup, recovery, or restore operations. Channels can be allocated and not used by a RUN command.

How does an incremental backup differ from a cumulative incremental backup?

Contains only blocks that have been modified since the last incremental backup

An incremental backup only contains blocks of a control file or the datafiles that have changed since the last incremental backup. A cumulative incremental backup backs up blocks changed since the last cumulative incremental backup and the previously backed up blocks.

Examine this RMAN command:

rman> run2> allocate channel d1 type disk;3> copy level 04> datafile 1 to '/backup/file1.dbf',5> datafile 2 to '/backup/file2.dbf';

Which task will this command accomplish?

Create an image copy backup that can be used in an incremental backup.

The PROD database has 10 datafiles stored on 2 disk drives. You need to perform a full database backup. How many files will be multiplexed per set if the FILESPERSET option is set to 3?

3

With the RMAN BACKUP command, the FILESPERSET option determines the number of files included in each set. In this example, four backup sets would be created. Three backup sets would be multiplexed by 3. The remaining file would be included in the fourth backup set.

If corrupt datafile blocks are detected during a backup set process, where are the addresses of the corrupt blocks recorded?

Control file

When errors are detected in blocks during a backup set process, the errors are written to the control files. To view the errors, query V$BACKUP_CORRUPTION. The corrupt files are still included in the backup set.

Why would you query V$BACKUP_REDOLOG?

V$BACKUP_REDOLOG will show the backup sets that include archived logs.

When backing up the database using the RMAN utility, in which two modes can the database be?

When taking an offline backup using RMAN, the database should be mounted, but not open. When taking an online backup using RMAN, the database should be open. When using RMAN, tablespaces should not be put in backup mode. If a recovery catalog is being used, it should be open for either type of backup.

If you are using RMAN to implement your backup and recovery strategy and the database is in NOARCHIVELOG mode, in which two states can the database be when you restore the datafiles?

The database must be in NOMOUNT or MOUNT state to use Recovery Manager to restore files in a database that is not archiving.

Which format value would you use in a backup set command to include the backup set number in the name of the backup file?

Theses are the valid values for the FORMAT option with the RMAN BACKUP command:%d - target database name%n - padded target database name%p - backup piece number%s - backup set number%t - backup set stamp%u - representation of the backup set number and time backup set was created

The PROD database has 10 datafiles stored on 2 disk drives. You need to perform a full database backup with 3 files in each backup set. How many channels should you allocate to perform a parallel backup operation?

To perform a parallel backup operation, allocate two channels of type disk to simultaneously read from the two disk drives that store the ten datafiles to be backed up.

What is a Recovery Manager backup set?

One or more files stored in the RMAN format

RMAN can be used to support backup sets, image copies, and O/S copies. A backup set is created using the RMAN BACKUP command. There are two types of backup sets. The datafile backup set can be used to backup datafiles and control files. The archived log backup set can be used to backup archived logs.

You have implemented an incremental backup strategy for the PROD database. What would happen if you needed to restore the control file for the PROD database?

The benefit of using an incremental backup may be lost.

If the control file of a database that uses incremental backups needs to be restored, the archived logs would have to be applied to the last full backup to recover the control file. The speed of recovery, which is one of the benefits of incremental backups, may be increased.

Why would you query V$SESSION_LONGOPS?

SESSION_LONGOPS displays the progress of a backup. If % Complete is not increasing, query V$SESSION_WAIT to see if any of the events have caused the backup to hang.

The PMON process encountered an error. Where are the details of this error recorded?

Trace files are created by the Oracle Server to document the errors generated by the background processes. The location of the trace files is specified by the BACKGROUND_DUMP_DEST initialization parameter.

An invalid checksum is detected on a redo log group member. What happens to archiving when this error is detected?

An attempt is made to archive another redo log member.

If the initialization parameter LOG_BLOCK_CHECKSUM is set to TRUE, each block in a redo log file is given a checksum before a write is performed. A checksum is used to detect block corruption before a block is read. If a corrupt block is detected in a member of a redo log group, the server will attempt to read from another member of the group. If the entire group is invalid, the group cannot be archived.

A user shuts down his computer without first disconnecting from the database. Which type of failure has occurred?

User process failure

A user process failure occurs when a user process abnormally terminates. This is usually caused by an abnormal disconnected user session. The PMON background process will automatically recover a user process failure.

Why would you specify the BLOCKSIZE parameter when using the DBVERIFY utility?

The block size of the file is greater than 2KB.

You have restarted the instance after a media failure. When will the rollback operation be performed?

When the application requests the data

Instance Recovery:

1. Oracle checks for unsynchronized files to determine if recovery is necessary.2. All the changes recorded in the redo log files are applied to the data blocks.3. The datafiles contain committed and uncommitted data.4. If the there is uncommitted data in the datafiles, the rollback operation occurs.5. After the roll forward and rollback operations, the data is committed.6. The datafiles are synchronized.

Which two tasks are performed in the roll forward process during recovery?

Active redo log files are applied to the data blocks.The log sequence numbers are updated in the datafiles.

During the roll forward phase of recovery, the redo logs are sequentially applied to the data blocks. After changes are made in the data blocks, the version number of the data blocks is incremented by 1.

If the DBWR process terminates and the database shuts down, which file logs the error that caused the process to terminate?

DBWR trace file

Which view would you query to determine which archived logs are needed for database recovery?

V$RECOVERY_LOG

What should you tell users after a datafile belonging to the SYSTEM tablespace is recovered in a database that is in ARCHIVELOG mode?

Reenter any data that was not committed at the point of failure.

To which point should you be able to recover the database from media failure if all archived log files are located in the default destination?

When media failure occurs in a database that is archiving and you have all the archived logs since the last backup, only the lost files need to be restored. The database can be recovered to the present time in the control file.

Which RMAN command updates the control file and recovery catalog when restoring a datafile after a media failure?

SWITCH

Take the tablespace for the datafile offline, copy the file to the new location using the SET NEWNAME command, and make the new datafile active by using the SWITCH command. The RECOVER command will apply the redo logs, archived logs, and incremental and cumulative backups to the file. Issue the ALTER TABLESPACE command to bring the tablespace online.

Evaluate this command:

ALTER DATABASE CLEAR LOGFILE GROUP 1 UNRECOVERABLE DATAFILE;

Why would you issue this command?

To clear a redo log file that is needed for recovery of an offline datafile

THE ALTER DATABASE CLEAR UNARCHIVED LOGFILE command can be used when there are only two log groups or the corrupt redo log file is a member of the current group. This command will clear or recreate the files.

The PROD database is in ARCHIVELOG mode. How would you recover the database if one of the datafiles belonging to the SYSTEM tablespace is corrupt?

Shut down the database, restore the corrupt file, mount the database, and recover the datafile.

Evaluate this command:

rman> run2> allocate channel d1 type disk;3> restore database;

If the database is in ARCHIVELOG mode, what will this command accomplish?

Recover only the datafiles from the last full backup

To open the database, the datafiles and the control file would need to be restored. This command only restores the datafiles. To restore the control, you would have to include the RESTORE CONTROLFILE command.

You are recovering from a disk failure with Recovery Manager and need to restore the dfuser02.dbf file in the USER_02 tablespace. Which command in your RUN command specifies the location to which the file should be restored?

SET NEWNAME FOR DATAFILE '/disk1/dfuser02.dbf'to '/disk2/dfuser02.dbf';

You issue this command:

SET AUTORECOVERY ONRECOVER DATABASE;

Which portion of the database is available for users while recovery is performed?

None

You need to perform an online complete recovery. Which tablespace cannot be included in the recovery operation?

SYSTEM

If you need to restore datafiles that are associated with the SYSTEM tablespace, you must restore the datafiles while the database is offline. All other files can be restored while the database is open. The tablespaces associated with the datafiles being restored should be offline.

The PROD database is in ARCHIVELOG mode and has two redo log groups. Which command should you issue if group 1 is the current group and it is corrupt?

ALTER DATABASE CLEAR UNARCHIVED LOGFILE GROUP 1;

Which view would you query to determine which datafiles need to be recovered?

V$RECOVER_FILE contains the names of the files that need to be recovered and the point that they need recovery from.

To recover the PROD database, you need to apply a large number of archived logs. Which command would you issue to automatically apply the archived logs when the recovery process is started?

SET AUTORECOVERY ON;

You can enable automatic recovery by issuing the SET AUTORECOVERY ON command. The redo log files must be in the location specified by the LOG_ARCHIVE_DEST initialization parameter. If you do not allow the Oracle Server to perform automatic recovery, you will be prompted for the redo log file names. It is recommended that you use the RECOVER command for media failure.

You are recovering from a disk failure with Recovery Manager and need to restore the dfuser02.df file in the USER_02 tablespace while the database is online. Which command should you issue after you allocate a channel and before you restore the datafile using the RUN command?

SQL "ALTER TABLESPACE user_02 OFFLINE IMMEDIATE";

Before any restore or recovery operation can be done to a tablespace in a database that is online, the tablespace must be taken offline. The SQL option allows you to issue SQL commands within Recovery Manager.

Which is an example of complete database recovery?

Recover all transactions to the point of failure

When a complete recovery is performed, committed transactions are not lost. After restoring the files, the redo logs and the archived logs are applied and the database is brought to the point of failure.

Why is it not beneficial to use RMAN when performing incomplete recovery?

A full offline backup is required after the recovery operations are complete.

After performing an incomplete recovery operation with RMAN, the database must be opened with the RESETLOGS option. After the database is open, a full offline backup should be taken. This process increases the amount of down time.

You have to perform a recovery because unwanted updates were made to the database. Which type of recovery operation will you perform?

Time-based recovery should be performed to restore the database to the state it was prior to the unwanted update.

Why would you use TableSpace Point-In-Time Recovery?

TSPITR allows one or more tablespaces to be restored to a point that is different from the rest of the database. The datafiles in the tablespace and a backup copy of the control file are required for the recovery operation. This method is used very sparingly. It will help the DBA recover from user errors when bad data was committed to a large table.

Which files are required when you recover a tablespace to a point-in-time?

Datafiles for the tablespace and a backup copy of the control file (see above)

Evaluate this command:

RESET DATABASE;

When performing an incomplete recovery using Recovery Manager, what will this command accomplish?

Register the current version of the database in the recovery catalog. The RESET DATABASE command in Recovery Manager will update the recovery catalog after the database has been recovered.

Which two restrictions will be placed on your export if you use the direct-path mode?

The client-side character set must match the server-side.The BUFFER parameter will not have any effect on the export.

In which order is data imported using the Import utility?

- Tables are created- Indexes are built- Data is imported- Triggers are imported- Integrity constraints are enabled.

A full database export was performed on Friday for the PROD database running in NOARCHIVELOG mode. On Monday afternoon a media failure occurs. Which type of recovery can you perform?

Point-In-Time

If a database is running in NOARCHIVELOG mode, the database can only be recovered to the point of the last backup regardless of the backup method.

Which Export parameter would you use to specify the password of the user whose schemayou are exporting?

USERID

How would you recover from a datafile corruption that affects the EMPLOYEE table if theindex on the table is still available?

Use an index scan to retrieve the data in the corrupt blocks.

To retrieve the data from the table, use this command:

SELECT DISTINCT(key)FROM corrupted_tableWHERE key> (lowest value for the key)AND substr(rowid, 1, 8) = corrupt_block_id order by 1;

You are recovering a read-only tablespace that was writable when the last backup was performed. How would you recover this tablespace?

Restore the last backup and recover until the time that the tablespace was made read-only.

When a tablespace becomes read-only, you should take a full backup so that this scenario never occurs. If you should need to recover a tablespace of this type, restore the last backup and apply the redo logs and archived logs to recover the tablespace to the point the tablespace became read-only.

How would you open a database in ARCHIVELOG mode with a missing a datafile?

Mount the database, take the tablespace with the missing datafile offline, and open the database.

To recover a lost datafile

- start up the database in MOUNT mode- take the tablespace with the missing datafile offline- open the database- restore the backup datafile and all offline redolog files with OS commands- recover the datafile (not the database !)- bring the tablespace online.

The tablespace will be recovered to the current time and the system will resynchronize the files. Committed data will not be lost.

How would you change the MAXDATAFILES parameter?

Recreate the control file using the CREATE CONTROLFILE command.

To change the MAXDATAFILES and MAXLOGMEMBERS parameters, you must recreate the control file. These settings are fixed when the control file is created and cannot be dynamically changed.

How many processes per disk drive are generally considered sufficient to perform a parallel recovery?

1 or 2

Parallel recovery helps to reduce the Mean-Time-To-Recover. The Oracle Server allows you to utilize multiple threads to recover the database. For example, to issue a recovery process that uses 4 recovery processes and two instances, you would issue this command:RECOVER DATABASE PARALLEL DEGREE 4 INSTANCES 2;This command will initiate 8 recovery processes. To minimize I/O contention, it is sufficient to have 1 to 2 processes per disk drive.

How would you recover from the loss of the recovery catalog if no backup control file exists?