impdp help=y
Import: Release 10.1.0.2.0 - Production on Saturday, 11 September, 2004 17:22
Copyright (c) 2003, Oracle. All rights reserved.
The Data Pump Import utility provides a mechanism for transferring data objects
between Oracle databases. The utility is invoked with the following command:
Example: impdp scott/tiger DIRECTORY=dmpdir DUMPFILE=scott.dmp
You can control how Import runs by entering the 'impdp' command followed
by various parameters. To specify parameters, you use keywords:
Format: impdp KEYWORD=value or KEYWORD=(value1,value2,...,valueN)
Example: impdp scott/tiger DIRECTORY=dmpdir DUMPFILE=scott.dmp
USERID must be the first parameter on the command line.
Keyword Description (Default)
------------------------------------------------------------------------------
ATTACH Attach to existing job, e.g. ATTACH [=job name].
CONTENT Specifies data to load where the valid keywords are:
(ALL), DATA_ONLY, and METADATA_ONLY.
DIRECTORY Directory object to be used for dump, log, and sql files.
DUMPFILE List of dumpfiles to import from (expdat.dmp),
e.g. DUMPFILE=scott1.dmp, scott2.dmp, dmpdir:scott3.dmp.
ESTIMATE Calculate job estimates where the valid keywords are:
(BLOCKS) and STATISTICS.
EXCLUDE Exclude specific object types, e.g. EXCLUDE=TABLE:EMP.
FLASHBACK_SCN SCN used to set session snapshot back to.
FLASHBACK_TIME Time used to get the SCN closest to the specified time.
FULL Import everything from source (Y).
HELP Display help messages (N).
INCLUDE Include specific object types, e.g. INCLUDE=TABLE_DATA.
JOB_NAME Name of import job to create.
LOGFILE Log file name (import.log).
NETWORK_LINK Name of remote database link to the source system.
NOLOGFILE Do not write logfile.
PARALLEL Change the number of active workers for current job.
PARFILE Specify parameter file.
QUERY Predicate clause used to import a subset of a table.
REMAP_DATAFILE Redefine datafile references in all DDL statements.
REMAP_SCHEMA Objects from one schema are loaded into another schema.
REMAP_TABLESPACE Tablespace object are remapped to another tablespace.
REUSE_DATAFILES Tablespace will be initialized if it already exists (N).
SCHEMAS List of schemas to import.
SKIP_UNUSABLE_INDEXES Skip indexes that were set to the Index Unusable state.
SQLFILE Write all the SQL DDL to a specified file.
STATUS Frequency (secs) job status is to be monitored where
the default (0) will show new status when available.
STREAMS_CONFIGURATION Enable the loading of Streams metadata
TABLE_EXISTS_ACTION Action to take if imported object already exists.
Valid keywords: (SKIP), APPEND, REPLACE and TRUNCATE.
TABLES Identifies a list of tables to import.
TABLESPACES Identifies a list of tablespaces to import.
TRANSFORM Metadata transform to apply (Y/N) to specific objects.
Valid transform keywords: SEGMENT_ATTRIBUTES and STORAGE.
ex. TRANSFORM=SEGMENT_ATTRIBUTES:N:TABLE.
TRANSPORT_DATAFILES List of datafiles to be imported by transportable mode.
TRANSPORT_FULL_CHECK Verify storage segments of all tables (N).
TRANSPORT_TABLESPACES List of tablespaces from which metadata will be loaded.
Only valid in NETWORK_LINK mode import operations.
VERSION Version of objects to export where valid keywords are:
(COMPATIBLE), LATEST, or any valid database version.
Only valid for NETWORK_LINK and SQLFILE.
The following commands are valid while in interactive mode.
Note: abbreviations are allowed
Command Description (Default)
------------------------------------------------------------------------------
CONTINUE_CLIENT Return to logging mode. Job will be re-started if idle.
EXIT_CLIENT Quit client session and leave job running.
HELP Summarize interactive commands.
KILL_JOB Detach and delete job.
PARALLEL Change the number of active workers for current job.
PARALLEL=.
START_JOB Start/resume current job.
START_JOB=SKIP_CURRENT will start the job after skipping
any action which was in progress when job was stopped.
STATUS Frequency (secs) job status is to be monitored where
the default (0) will show new status when available.
STATUS=[interval]
STOP_JOB Orderly shutdown of job execution and exits the client.
STOP_JOB=IMMEDIATE performs an immediate shutdown of the
Data Pump job.
Oracle 10 DBA Interview questions and answers
1. Is the following SQL statement syntactically correct? If not, please rewrite it correctly.
SELECT col1 FROM tableA WHERE NOT IN (SELECT col1 FROM tableB);
Ans. SQL is incorrect.
Correct SQL : SELECT col1 FROM tableA WHERE col1 NOT IN (SELECT col1 FROM tableB);
2. What is a more efficient way to write this query, to archive the same set?
Ans: SELECT col1 from tableA minus SELECT col1 from tableB
3.How would you determine that the new query is more efficient than the original query?
Ans: Run explain plan on both query and see the result .
4.How can we find the location of the database trace files from within the data dictionary?
Ans: Generally trace file on the database server machine is located in one of two locations:
1. If you are using a dedicated server connection, the trace file will be generated in the directory specified by
the USER_DUMP_DEST parameter.
2.If you are using a shared server connection, the trace file will be generated in the directory specified by the
BACKGROUND_DUMP_DEST parameter.
you can run sqlplus>SHOW PARAMETER DUMP_DEST
or
select name, value
from v$parameter
where name like '%dump_dest%'
5. What is the correct syntax for a UNIX endless WHILE loop?
while :
do
commands
done
6. Write the SQL statement that will return the name and size of the largest datafile in the database.
SQL> select name,bytes from v$datafile where bytes=(select max(bytes) from v$datafile);
7. What are the proper steps to changing the Oracle database block size?
cold backup all data files and backup controlfile to trace, recreate your database
with the new block size using the backup control file, and restore. It may be easier
with rman. You can not change datbase block size on fly.
8. Using awk, write a script to print the 3rd field of every line.
Ans:
awk '{print }'
awk '{print $3}
awk '{print $3}
9.Under what conditions, is a nested loop better than a merge join?
Ans:
Optimizer uses nested loop when we are joining tables containing small number of rows with an efficient driving
condition.
It is important to have an index on column of inner join table as this table is probed every time for a new value
from outer table.
Optimizer may not use nested loop in case:
1. No of rows of both the table is quite high
2. Inner query always results in same set of records
3. The access path of inner table is independent of data coming from outer table.
merge join is used to join two independent data sources. They perform better than nested loop when the volume of
data is big in tables
but not as good as hash joins in general.
10.Which database views would you use to ascertain the number of commits a user's session has performed?
Joining V$SESSTAT ,V$STATNAME
select * from V$SESSTAT a ,V$STATNAME b where b.CLASS=a.STATISTIC# and b.NAME='user commits' and a.sid=
11.What does the #!bin/ksh at the beginning of a shell script do? Why should it be there?
Ans: On the first line of an interpreter script, the "#!", is the name of a program which should be used to
interpret the contents of the file.
For instance, if the first line contains "#! /bin/ksh", then the contents of the file are executed as a korn shell
script.
12.What command is used to find the status of Oracle 10g Clusterware (CRS) and the various components it manages
(ONS, VIP, listener, instances, etc.)?
Ans:
$ocrcheck
13.Describe a scenario in which a vendor clusterware is required, in addition to the Oracle 10g Clusterware.
If you choose external redundancy for the OCR and voting disk, then to enable redundancy, the disk subsystem must be configurable for RAID mirroring/vendor clusterware. Otherwise, your system may be vulnerable because the OCR and voting disk are single points of failure.
14.How would you find the interconnect IP address from any node within an Oracle 10g RAC configuration?
using oifcfg command.
se the oifcfg -help command to display online help for OIFCFG. The elements of OIFCFG commands, some of which are
optional depending on the command, are:
*nodename—Name of the Oracle Clusterware node as listed in the output from the olsnodes command
*if_name—Name by which the interface is configured in the system
*subnet—Subnet address of the interface
*if_type—Type of interface: public or cluster_interconnect
You can use OIFCFG to list the interface names and the subnets of all of the interfaces available on the local node
by executing the iflist keyword as shown in this example:
oifcfg iflist
hme0 139.185.141.0
qfe0 204.152.65.16
You can also retrieve specific OIFCFG information with a getif command using the following syntax:
oifcfg getif [ [-global | -node nodename] [-if if_name[/subnet]] [-type if_type] ]
To store a new interface use the setif keyword. For example, to store the interface hme0, with the subnet
139.185.141.0, as a global interface (to be used as an interconnect for all of the RAC instances in your cluster),
you would use the command:
oifcfg setif -global hme0/139.185.141.0:cluster_interconnect
For a cluster interconnect that exists between only two nodes, for example rac1 and rac2, you could create the cms0
interface with the following commands, assuming 139.185.142.0 is the subnet addresses for the interconnect on rac1
and rac2 respectively:
oifcfg setif -global cms0/139.185.142.0:cluster_interconnect
Use the OIFCFG delif command to delete the stored configuration for global or node-specific interfaces. A specific
node-specific or global interface can be deleted by supplying the interface name, with an optional subnet, on the
command line. Without the -node or -global options, the delif keyword deletes either the given interface or all of
the global and node-specific interfaces on all of the nodes in the cluster. For example, the following command
deletes the global interface named qfe0 for the subnet 204.152.65.0:
oifcfg delif -global qfe0/204.152.65.0
On the other hand, the next command deletes all of the global interfaces stored with OIFCFG:
oifcfg delif -global
15.What is the Purpose of the voting disk in Oracle 10g Clusterware?
Voting disk record node membership information. Oracle Clusterware uses the voting disk to determine which instances are members of a cluster. The voting disk must reside on a shared disk. For high availability, Oracle recommends that you have a minimum of three voting disks. If you configure a single voting disk, then you should use external mirroring to provide redundancy. You can have up to 32 voting disks in your cluster.
16.What is the purpose of the OCR in Oracle 10g Clusterware?
Ans: Oracle Cluster Registry (OCR) is a component in 10g RAC used to store the cluster configuration information. It is a shared disk component, typically located in a shared raw volume that must be accessible to all nodes in the cluster.
The daemon OCSSd manages the configuration info in OCR and maintains the changes to cluster in the registry.
17. In Oracle Streams archived log downstream capture, which database view can be used to determine which archived
logs are no longer needed by the capture process?
Ans: V$ARCHIVE_DEST_STATUS
SELECT col1 FROM tableA WHERE NOT IN (SELECT col1 FROM tableB);
Ans. SQL is incorrect.
Correct SQL : SELECT col1 FROM tableA WHERE col1 NOT IN (SELECT col1 FROM tableB);
2. What is a more efficient way to write this query, to archive the same set?
Ans: SELECT col1 from tableA minus SELECT col1 from tableB
3.How would you determine that the new query is more efficient than the original query?
Ans: Run explain plan on both query and see the result .
4.How can we find the location of the database trace files from within the data dictionary?
Ans: Generally trace file on the database server machine is located in one of two locations:
1. If you are using a dedicated server connection, the trace file will be generated in the directory specified by
the USER_DUMP_DEST parameter.
2.If you are using a shared server connection, the trace file will be generated in the directory specified by the
BACKGROUND_DUMP_DEST parameter.
you can run sqlplus>SHOW PARAMETER DUMP_DEST
or
select name, value
from v$parameter
where name like '%dump_dest%'
5. What is the correct syntax for a UNIX endless WHILE loop?
while :
do
commands
done
6. Write the SQL statement that will return the name and size of the largest datafile in the database.
SQL> select name,bytes from v$datafile where bytes=(select max(bytes) from v$datafile);
7. What are the proper steps to changing the Oracle database block size?
cold backup all data files and backup controlfile to trace, recreate your database
with the new block size using the backup control file, and restore. It may be easier
with rman. You can not change datbase block size on fly.
8. Using awk, write a script to print the 3rd field of every line.
Ans:
awk
awk '{print $3}
awk '{print $3}
9.Under what conditions, is a nested loop better than a merge join?
Ans:
Optimizer uses nested loop when we are joining tables containing small number of rows with an efficient driving
condition.
It is important to have an index on column of inner join table as this table is probed every time for a new value
from outer table.
Optimizer may not use nested loop in case:
1. No of rows of both the table is quite high
2. Inner query always results in same set of records
3. The access path of inner table is independent of data coming from outer table.
merge join is used to join two independent data sources. They perform better than nested loop when the volume of
data is big in tables
but not as good as hash joins in general.
10.Which database views would you use to ascertain the number of commits a user's session has performed?
Joining V$SESSTAT ,V$STATNAME
select * from V$SESSTAT a ,V$STATNAME b where b.CLASS=a.STATISTIC# and b.NAME='user commits' and a.sid=
11.What does the #!bin/ksh at the beginning of a shell script do? Why should it be there?
Ans: On the first line of an interpreter script, the "#!", is the name of a program which should be used to
interpret the contents of the file.
For instance, if the first line contains "#! /bin/ksh", then the contents of the file are executed as a korn shell
script.
12.What command is used to find the status of Oracle 10g Clusterware (CRS) and the various components it manages
(ONS, VIP, listener, instances, etc.)?
Ans:
$ocrcheck
13.Describe a scenario in which a vendor clusterware is required, in addition to the Oracle 10g Clusterware.
If you choose external redundancy for the OCR and voting disk, then to enable redundancy, the disk subsystem must be configurable for RAID mirroring/vendor clusterware. Otherwise, your system may be vulnerable because the OCR and voting disk are single points of failure.
14.How would you find the interconnect IP address from any node within an Oracle 10g RAC configuration?
using oifcfg command.
se the oifcfg -help command to display online help for OIFCFG. The elements of OIFCFG commands, some of which are
optional depending on the command, are:
*nodename—Name of the Oracle Clusterware node as listed in the output from the olsnodes command
*if_name—Name by which the interface is configured in the system
*subnet—Subnet address of the interface
*if_type—Type of interface: public or cluster_interconnect
You can use OIFCFG to list the interface names and the subnets of all of the interfaces available on the local node
by executing the iflist keyword as shown in this example:
oifcfg iflist
hme0 139.185.141.0
qfe0 204.152.65.16
You can also retrieve specific OIFCFG information with a getif command using the following syntax:
oifcfg getif [ [-global | -node nodename] [-if if_name[/subnet]] [-type if_type] ]
To store a new interface use the setif keyword. For example, to store the interface hme0, with the subnet
139.185.141.0, as a global interface (to be used as an interconnect for all of the RAC instances in your cluster),
you would use the command:
oifcfg setif -global hme0/139.185.141.0:cluster_interconnect
For a cluster interconnect that exists between only two nodes, for example rac1 and rac2, you could create the cms0
interface with the following commands, assuming 139.185.142.0 is the subnet addresses for the interconnect on rac1
and rac2 respectively:
oifcfg setif -global cms0/139.185.142.0:cluster_interconnect
Use the OIFCFG delif command to delete the stored configuration for global or node-specific interfaces. A specific
node-specific or global interface can be deleted by supplying the interface name, with an optional subnet, on the
command line. Without the -node or -global options, the delif keyword deletes either the given interface or all of
the global and node-specific interfaces on all of the nodes in the cluster. For example, the following command
deletes the global interface named qfe0 for the subnet 204.152.65.0:
oifcfg delif -global qfe0/204.152.65.0
On the other hand, the next command deletes all of the global interfaces stored with OIFCFG:
oifcfg delif -global
15.What is the Purpose of the voting disk in Oracle 10g Clusterware?
Voting disk record node membership information. Oracle Clusterware uses the voting disk to determine which instances are members of a cluster. The voting disk must reside on a shared disk. For high availability, Oracle recommends that you have a minimum of three voting disks. If you configure a single voting disk, then you should use external mirroring to provide redundancy. You can have up to 32 voting disks in your cluster.
16.What is the purpose of the OCR in Oracle 10g Clusterware?
Ans: Oracle Cluster Registry (OCR) is a component in 10g RAC used to store the cluster configuration information. It is a shared disk component, typically located in a shared raw volume that must be accessible to all nodes in the cluster.
The daemon OCSSd manages the configuration info in OCR and maintains the changes to cluster in the registry.
17. In Oracle Streams archived log downstream capture, which database view can be used to determine which archived
logs are no longer needed by the capture process?
Ans: V$ARCHIVE_DEST_STATUS
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