Oracle CORE DBA: 2012

Before Using Export

· Run the catexp.sql or catalog.sql script

· Ensure there is sufficient disk or tape storage to write the export file

· Verify that you have the required access privileges

To use Export, you must run the script catexp.sql or catalog.sql (which runs catexp.sql) after the database has been created.

catexp.sql or catalog.sql needs to be run only once on a database.

You do not need to run it again before you perform the export. The script performs the following tasks to prepare the database for Export:

· Creates the necessary export views in the data dictionary

· Creates the EXP_FULL_DATABASE role

· Assigns all necessary privileges to the EXP_FULL_DATABASE role

· Assigns EXP_FULL_DATABASE to the DBA role

· Records the version of catexp.sql that has been installed

Ensuring Sufficient Disk Space

Before you run Export, ensure that there is sufficient disk or tape storage space to write the export file. If there is not enough space, Export terminates with a write-failure error.

You can use table sizes to estimate the maximum space needed. You can find table sizes in the USER_SEGMENTS view of the Oracle data dictionary. The following query displays disk usage for all tables:

SELECT SUM(BYTES) FROM USER_SEGMENTS WHERE SEGMENT_TYPE='TABLE';

The result of the query does not include disk space used for data stored in LOB (large object) or VARRAY columns or in partitioned tables.

Verifying Access Privileges

To use Export, you must have the CREATE SESSION privilege on an Oracle database. To export tables owned by another user, you must have the EXP_FULL_DATABASE role enabled. This role is granted to all DBAs.

If you do not have the system privileges contained in the EXP_FULL_DATABASE role, you cannot export objects contained in another user's schema. For example, you cannot export a table in another user's schema, even if you created a synonym for it.

The following schema names are reserved and will not be processed by Export:

· ORDSYS

· MDSYS

· CTXSYS

· ORDPLUGINS

· LBACSYS

Invoking Export

You can invoke Export and specify parameters by using any of the following methods:

· Command-line entries

· Interactive Export prompts

· Parameter files

Before you use one of these methods to invoke Export, be sure to read the descriptions of the available parameters

Command-Line Entries

You can specify all valid parameters and their values from the command line using the following syntax:

exp username/password PARAMETER=value

exp username/password PARAMETER=(value1,value2,...,valuen)

The number of parameters cannot exceed the maximum length of a command line on the system.

Interactive Export Prompts

If you prefer to let Export prompt you for the value of each parameter, you can use the following syntax to start Export in interactive mode:

exp username/password

Export will display commonly used parameters with a request for you to enter a value. This method exists for backward compatibility and is not recommended because it provides less functionality than the other methods.

Parameter Files

You can specify all valid parameters and their values in a parameter file. Storing the parameters in a file allows them to be easily modified or reused, and is the recommended method for invoking Export. If you use different parameters for different databases, you can have multiple parameter files.

Create the parameter file using any flat file text editor. The command-line option PARFILE=filename tells Export to read the parameters from the specified file rather than from the command line. For example:

exp PARFILE=filename

exp username/password PARFILE=filename

The first example does not specify the username/password on the command line to illustrate that you can specify them in the parameter file, although, for security reasons, this is not recommended.

The syntax for parameter file specifications is one of the following:

PARAMETER=value

PARAMETER=(value)

PARAMETER=(value1, value2, ...)

The following example shows a partial parameter file listing:

FULL=y

FILE=dba.imp

GRANTS=y

INDEXES=y

CONSISTENT=y

You can add comments to the parameter file by preceding them with the pound (#) sign. Export ignores all characters to the right of the pound (#) sign.

You can specify a parameter file at the same time that you are entering parameters on the command line. In fact, you can specify the same parameter in both places. The position of the PARFILE parameter and other parameters on the command line determines which parameters take precedence. For example, assume the parameter file params.dat contains the parameter INDEXES=y and Export is invoked with the following line:

exp username/password PARFILE=params.dat INDEXES=n

In this case, because INDEXES=n occurs after PARFILE=params.dat, INDEXES=n overrides the value of the INDEXES parameter in the parameter file.

Invoking Export As SYSDBA

SYSDBA is used internally and has specialized functions; its behavior is not the same as for generalized users. Therefore, you should not typically need to invoke Export as SYSDBA, except in the following situations:

· At the request of Oracle technical support

· When using transportable tablespaces

Transportable Tablespaces

The transportable tablespace feature enables you to move a set of tablespaces from one Oracle database to another.

To move or copy a set of tablespaces, you must make the tablespaces read-only, copy the datafiles of these tablespaces, and use Export and Import to move the database information (metadata) stored in the data dictionary. Both the datafiles and the metadata export file must be copied to the target database. The transport of these files can be done using any facility for copying flat binary files, such as the operating system copying facility, binary-mode FTP, or publishing on CD-ROMs.

After copying the datafiles and exporting the metadata, you can optionally put the tablespaces in read/write mode.

Export provides the following parameters to enable export of transportable tablespace metadata.

· TABLESPACES

· TRANSPORT_TABLESPACE

To invoke Export as SYSDBA, use the following syntax, adding any desired parameters or parameter filenames:

exp \'username/password AS SYSDBA\'

Optionally, you could also specify an instance name:

exp \'username/password@instance AS SYSDBA\'

If either the username or password is omitted, Export will prompt you for it.

Export Modes

The Export utility provides four modes of export:

· Full

· User (Owner)

· Table

· Tablespace

All users can export in table mode and user mode. Users with the EXP_FULL_DATABASE role (privileged users) can export in all modes.

Objects Exported and Imported in Each Mode

Object	Table Mode	User Mode	Full Database Mode	Tablespace Mode
Analyze cluster	No	Yes	Yes	No
Analyze tables/statistics	Yes	Yes	Yes	Yes
Application contexts	No	No	Yes	No
Auditing information	Yes	Yes	Yes	No
B-tree, bitmap, domain functional indexes	Yes^{Foot 1}	Yes^{Footref 1}	Yes	Yes
Cluster definitions	No	Yes	Yes	Yes
Column and table comments	Yes	Yes	Yes	Yes
Database links	No	Yes	Yes	No
Default roles	No	No	Yes	No
Dimensions	No	Yes	Yes	No
Directory aliases	No	No	Yes	No
External tables (without data)	Yes	Yes	Yes	No
Foreign function libraries	No	Yes	Yes	No
Indexes owned by users other than table owner	Yes (Privileged users only)	Yes	Yes	Yes
Index types	No	Yes	Yes	No
Java resources and classes	No	Yes	Yes	No
Job queues	No	Yes	Yes	No
Nested table data	Yes	Yes	Yes	Yes
Object grants	Yes (Only for tables and indexes)	Yes	Yes	Yes
Object type definitions used by table	Yes	Yes	Yes	Yes
Object types	No	Yes	Yes	No
Operators	No	Yes	Yes	No
Password history	No	No	Yes	No
Postinstance actions and objects	No	No	Yes	No
Postschema procedural actions and objects	No	Yes	Yes	No
Posttable actions	Yes	Yes	Yes	Yes
Posttable procedural actions and objects	Yes	Yes	Yes	Yes
Preschema procedural objects and actions	No	Yes	Yes	No
Pretable actions	Yes	Yes	Yes	Yes
Pretable procedural actions	Yes	Yes	Yes	Yes
Private synonyms	No	Yes	Yes	No
Procedural objects	No	Yes	Yes	No
Profiles	No	No	Yes	No
Public synonyms	No	No	Yes	No
Referential integrity constraints	Yes	Yes	Yes	No
Refresh groups	No	Yes	Yes	No
Resource costs	No	No	Yes	No
Role grants	No	No	Yes	No
Roles	No	No	Yes	No
Rollback segment definitions	No	No	Yes	No
Security policies for table	Yes	Yes	Yes	Yes
Sequence numbers	No	Yes	Yes	No
Snapshot logs	No	Yes	Yes	No
Snapshots and materialized views	No	Yes	Yes	No
System privilege grants	No	No	Yes	No
Table constraints (primary, unique, check)	Yes	Yes	Yes	Yes
Table data	Yes	Yes	Yes	No
Table definitions	Yes	Yes	Yes	Yes
Tablespace definitions	No	No	Yes	No
Tablespace quotas	No	No	Yes	No
Triggers	Yes	Yes^{Foot 2}	Yes^{Foot 3}	Yes
Triggers owned by other users	Yes (Privileged users only)	No	No	No
User definitions	No	No	Yes	No
User proxies	No	No	Yes	No
User views	No	Yes	Yes	No
User-stored procedures, packages, and functions	No	Yes	Yes	No

Table-Level and Partition-Level Export

You can export tables, partitions, and subpartitions in the following ways:

· Table-level Export: exports all data from the specified tables

· Partition-level Export: exports only data from the specified source partitions or subpartitions

In all modes, partitioned data is exported in a format such that partitions or subpartitions can be imported selectively.

Table-Level Export

In table-level Export, you can export an entire table (partitioned or nonpartitioned) along with its indexes and other table-dependent objects. If the table is partitioned, all of its partitions and subpartitions are also exported. This applies to both direct path Export and conventional path Export. You can perform a table-level export in any Export mode.

Partition-Level Export

In partition-level Export, you can export one or more specified partitions or subpartitions of a table. You can only perform a partition-level export in Table mode.

Processing Restrictions

The following restrictions apply when you process data with the Export and Import utilities:

· Java classes, resources, and procedures that are created using Enterprise Java Beans (EJBs) are not placed in the export file.

· Constraints that have been altered using the RELY keyword lose the RELY attribute when they are exported.

· When a type definition has evolved and then data referencing that evolved type is exported, the type definition on the import system must have evolved in the same manner.

Export Parameters

BUFFER

Default: operating system-dependent. See your Oracle operating system-specific documentation to determine the default value for this parameter.

Specifies the size, in bytes, of the buffer used to fetch rows. As a result, this parameter determines the maximum number of rows in an array fetched by Export. Use the following formula to calculate the buffer size:

buffer_size = rows_in_array * maximum_row_size

If you specify zero, the Export utility fetches only one row at a time.

Tables with columns of type LONG, LOB, BFILE, REF, ROWID, LOGICAL ROWID, or DATE are fetched one row at a time.

Note:

The BUFFER parameter applies only to conventional path Export. It has no effect on a direct path Export.

Example: Calculating Buffer Size

This section shows an example of how to calculate buffer size.

The following table is created:

CREATE TABLE sample (name varchar(30), weight number);

The maximum size of the name column is 30, plus 2 bytes for the indicator. The maximum size of the weight column is 22 (the size of the internal representation for Oracle numbers), plus 2 bytes for the indicator.

Therefore, the maximum row size is 56 (30+2+22+2).

To perform array operations for 100 rows, a buffer size of 5600 should be specified.

COMPRESS

Default: y

Specifies how Export and Import manage the initial extent for table data.

The default, COMPRESS=y, causes Export to flag table data for consolidation into one initial extent upon Import. If extent sizes are large (for example, because of the PCTINCREASE parameter), the allocated space will be larger than the space required to hold the data.

If you specify COMPRESS=n, Export uses the current storage parameters, including the values of initial extent size and next extent size. The values of the parameters may be the values specified in the CREATE TABLE or ALTER TABLE statements or the values modified by the database system. For example, the NEXT extent size value may be modified if the table grows and if the PCTINCREASE parameter is nonzero.

Note:

Although the actual consolidation is performed upon import, you can specify the COMPRESS parameter only when you export, not when you import. The Export utility, not the Import utility, generates the data definitions, including the storage parameter definitions. Therefore, if you specify COMPRESS=y when you export, you can import the data in consolidated form only.

Note:

LOB data is not compressed. For LOB data, values of initial extent size and next extent size at the time of export are used.

CONSISTENT

Default: n

Specifies whether or not Export uses the SET TRANSACTION READ ONLY statement to ensure that the data seen by Export is consistent to a single point in time and does not change during the execution of the exp command. You should specify CONSISTENT=y when you anticipate that other applications will be updating the target data after an export has started.

If you use CONSISTENT=n, each table is usually exported in a single transaction. However, if a table contains nested tables, the outer table and each inner table are exported as separate transactions. If a table is partitioned, each partition is exported as a separate transaction.

Therefore, if nested tables and partitioned tables are being updated by other applications, the data that is exported could be inconsistent. To minimize this possibility, export those tables at a time when updates are not being done.

Sequence of Events During Updates by Two Users

TIme Sequence	User1	User2
1	Begins export of TAB:P1	No activity
2	No activity	Updates TAB:P2 Updates TAB:P1 Commits transaction
3	Ends export of TAB:P1	No activity
4	Exports TAB:P2	No activity

If the export uses CONSISTENT=y, none of the updates by user2 are written to the export file.

If the export uses CONSISTENT=n, the updates to TAB:P1 are not written to the export file. However, the updates to TAB:P2 are written to the export file because the update transaction is committed before the export of TAB:P2 begins. As a result, the user2 transaction is only partially recorded in the export file, making it inconsistent.

If you use CONSISTENT=y and the volume of updates is large, the rollback segment usage will be large. In addition, the export of each table will be slower because the rollback segment must be scanned for uncommitted transactions.

Keep in mind the following points about using CONSISTENT=y:

· CONSISTENT=y is unsupported for exports that are performed when you are connected as user SYS or you are using AS SYSDBA, or both.

· Export of certain metadata may require the use of the SYS schema within recursive SQL. In such situations, the use of CONSISTENT=y will be ignored. Oracle Corporation recommends that you avoid making metadata changes during an export process in which CONSISTENT=y is selected.

· To minimize the time and space required for such exports, you should export tables that need to remain consistent separately from those that do not.

For example, export the emp and dept tables together in a consistent export, and then export the remainder of the database in a second pass.

· A "snapshot too old" error occurs when rollback space is used up, and space taken up by committed transactions is reused for new transactions. Reusing space in the rollback segment allows database integrity to be preserved with minimum space requirements, but it imposes a limit on the amount of time that a read-consistent image can be preserved.

If a committed transaction has been overwritten and the information is needed for a read-consistent view of the database, a "snapshot too old" error results.

To avoid this error, you should minimize the time taken by a read-consistent export. (Do this by restricting the number of objects exported and, if possible, by reducing the database transaction rate.) Also, make the rollback segment as large as possible.

CONSTRAINTS

Default: y

Specifies whether or not the Export utility exports table constraints.

DIRECT

Default: n

Specifies whether you use direct path or conventional path Export.

Specifying DIRECT=y causes Export to extract data by reading the data directly, bypassing the SQL command-processing layer (evaluating buffer). This method can be much faster than a conventional path Export.

FEEDBACK

Default: 0 (zero)

Specifies that Export should display a progress meter in the form of a period for n number of rows exported. For example, if you specify FEEDBACK=10, Export displays a period each time 10 rows are exported. The FEEDBACK value applies to all tables being exported; it cannot be set on a per-table basis.

FILESIZE

Default: Data is written to one file until the maximum size, as specified in Table 1-3, is reached.

Export supports writing to multiple export files, and Import can read from multiple export files. If you specify a value (byte limit) for the FILESIZE parameter, Export will write only the number of bytes you specify to each dump file.

When the amount of data Export must write exceeds the maximum value you specified for FILESIZE, it will get the name of the next export file from the FILE parameter (see FILE for more information) or, if it has used all the names specified in the FILE parameter, it will prompt you to provide a new export filename. If you do not specify a value for FILESIZE (note that a value of 0 is equivalent to not specifying FILESIZE), then Export will write to only one file, regardless of the number of files specified in the FILE parameter.

Note:

If the space requirements of your export file exceed the available disk space, Export will abort, and you will have to repeat the Export after making sufficient disk space available.

The FILESIZE parameter has a maximum value equal to the maximum value that can be stored in 64 bits.

The FILESIZE value can also be specified as a number followed by KB (number of kilobytes). For example, FILESIZE=2KB is the same as FILESIZE=2048. Similarly, MB specifies megabytes (1024 * 1024) and GB specifies gigabytes (1024**3). B remains the shorthand for bytes; the number is not multiplied to obtain the final file size (FILESIZE=2048B is the same as FILESIZE=2048).

FLASHBACK_SCN

Default: none

Specifies the system change number (SCN) that Export will use to enable flashback. The export operation is performed with data consistent as of this specified SCN.

FLASHBACK_TIME

Default: none

Specifies a time. Export finds the SCN that most closely matches the specified time. This SCN is used to enable flashback. The export operation is performed with data consistent as of this SCN.

FULL

Default: n

Indicates that the Export is a full database mode Export (that is, it exports the entire database). Specify FULL=y to export in full database mode. You need to have the EXP_FULL_DATABASE role to export in this mode.

GRANTS

Default: y

Specifies whether or not the Export utility exports object grants. The object grants that are exported depend on whether you use full database mode or user mode. In full database mode, all grants on a table are exported. In user mode, only those granted by the owner of the table are exported. System privilege grants are always exported.

HELP

Default: none

Displays a description of the Export parameters. Enter exp help=y on the command line to invoke it.

INDEXES

Default: y

Specifies whether or not the Export utility exports indexes.

LOG

Default: none

Specifies a filename to receive informational and error messages. For example:

exp SYSTEM/password LOG=export.log

If you specify this parameter, messages are logged in the log file and displayed to the terminal display.

OBJECT_CONSISTENT

Default: n

Specifies whether or not the Export utility uses the SET TRANSACTION READ ONLY statement to ensure that the data exported is consistent to a single point in time and does not change during the export. If OBJECT_CONSISTENT is set to y, each object is exported in its own read-only transaction, even if it is partitioned. In contrast, if you use the CONSISTENT parameter, then there is only one read-only transaction.

OWNER

Default: none

Indicates that the Export is a user-mode Export and lists the users whose objects will be exported. If the user initiating the export is the DBA, multiple users may be listed.

PARFILE

Default: none

Specifies a filename for a file that contains a list of Export parameters. For more information on using a parameter file, see Invoking Export.

QUERY

Default: none

This parameter allows you to select a subset of rows from a set of tables when doing a table mode export. The value of the query parameter is a string that contains a WHERE clause for a SQL SELECT statement that will be applied to all tables (or table partitions) listed in the TABLE parameter.

For example, if user scott wants to export only those employees whose job title is SALESMAN and whose salary is less than 1600, he could do the following (this example is UNIX-based):

exp scott/tiger TABLES=emp QUERY=\"WHERE job=\'SALESMAN\' and sal \<1600\"

When executing this query, Export builds a SQL SELECT statement similar to the following:

SELECT * FROM emp WHERE job='SALESMAN' and sal <1600;

The values specified for the QUERY parameter are applied to all tables (or table partitions) listed in the TABLE parameter. For example, the following statement will unload rows in both emp and bonus that match the query:

exp scott/tiger TABLES=emp,bonus QUERY=\"WHERE job=\'SALESMAN\' and sal\<1600\"

Again, the SQL statements that Export executes are similar to the following:

SELECT * FROM emp WHERE job='SALESMAN' and sal <1600;

SELECT * FROM bonus WHERE job='SALESMAN' and sal <1600;

If a table is missing the columns specified in the QUERY clause, an error message will be produced, and no rows will be exported for the offending table

Restrictions

· The parameter QUERY cannot be specified for full, user, or tablespace mode exports.

· The parameter QUERY must be applicable to all specified tables.

· The parameter QUERY cannot be specified in a direct path export (DIRECT=y)

· The parameter QUERY cannot be specified for tables with inner nested tables.

· You cannot determine from the contents of the export file whether the data is the result of a QUERY export.

RECORDLENGTH

Default: operating system-dependent

Specifies the length, in bytes, of the file record. The RECORDLENGTH parameter is necessary when you must transfer the export file to another operating system that uses a different default value.

If you do not define this parameter, it defaults to your platform-dependent value for buffer size. For more information about the buffer size default value, see your Oracle operating system-specific documentation.

You can set RECORDLENGTH to any value equal to or greater than your system's buffer size. (The highest value is 64 KB.) Changing the RECORDLENGTH parameter affects only the size of data that accumulates before writing to the disk. It does not affect the operating system file block size.

See your Oracle operating system-specific documentation to determine the proper value or to create a file with a different record size.

RESUMABLE

Default: n

The RESUMABLE parameter is used to enable and disable resumable space allocation. Because this parameter is disabled by default, you must set RESUMABLE=y in order to use its associated parameters, RESUMABLE_NAME and RESUMABLE_TIMEOUT.

RESUMABLE_NAME

Default: 'User USERNAME (USERID), Session SESSIONID, Instance INSTANCEID'

The value for this parameter identifies the statement that is resumable. This value is a user-defined text string that is inserted in either the USER_RESUMABLE or DBA_RESUMABLE view to help you identify a specific resumable statement that has been suspended.

This parameter is ignored unless the RESUMABLE parameter is set to y to enable resumable space allocation.

RESUMABLE_TIMEOUT

Default: 7200 seconds (2 hours)

The value of the parameter specifies the time period during which an error must be fixed. If the error is not fixed within the timeout period, execution of the statement is aborted.

This parameter is ignored unless the RESUMABLE parameter is set to y to enable resumable space allocation.

ROWS

Default: y

Specifies whether or not the rows of table data are exported.

STATISTICS

Default: ESTIMATE

Specifies the type of database optimizer statistics to generate when the exported data is imported. Options are ESTIMATE, COMPUTE, and NONE. See the Import parameter STATISTICS and Importing Statistics.

In some cases, Export will place the precalculated statistics in the export file as well as the ANALYZE statements to regenerate the statistics.

However, the precalculated optimizer statistics will not be used at export time if a table has columns with system-generated names.

The precalculated optimizer statistics are flagged as questionable at export time if:

· There are row errors while exporting

· The client character set or NCHAR character set does not match the server character set or NCHAR character set

· A QUERY clause is specified

· Only certain partitions or subpartitions are exported

TABLES

Default: none

Specifies that the Export is a table-mode Export and lists the table names and partition and subpartition names to export. You can specify the following when you specify the name of the table:

· schemaname specifies the name of the user's schema from which to export the table or partition. The schema names ORDSYS, MDSYS, CTXSYS, and ORDPLUGINS are reserved by Export.

· tablename specifies the name of the table or tables to be exported. Table-level export lets you export entire partitioned or nonpartitioned tables. If a table in the list is partitioned and you do not specify a partition name, all its partitions and subpartitions are exported.

The table name can contain any number of '%' pattern matching characters, which can each match zero or more characters in the table name against the table objects in the database. All the tables in the relevant schema that match the specified pattern are selected for export, as if the respective table names were explicitly specified in the parameter.

· partition_name indicates that the export is a partition-level Export. Partition-level Export lets you export one or more specified partitions or subpartitions within a table.

The syntax you use to specify the preceding is in the form:

schemaname.tablename:partition_name

schemaname.tablename:subpartition_name

If you use tablename:partition_name, the specified table must be partitioned, and partition_name must be the name of one of its partitions or subpartitions. If the specified table is not partitioned, the partition_name is ignored and the entire table is exported.

See Example Export Session Using Partition-Level Export for several examples of partition-level exports.

Note:

Some operating systems, such as UNIX, require that you use escape characters before special characters, such as a parenthesis, so that the character is not treated as a special character. On UNIX, use a backslash (\) as the escape character, as shown in the following example:

TABLES=$emp,dept$

Table Name Restrictions

The following restrictions apply to table names:

· By default, table names in a database are stored as uppercase. If you have a table name in mixed-case or lowercase, and you want to preserve case-sensitivity for the table name, you must enclose the name in quotation marks. The name must exactly match the table name stored in the database.

Some operating systems require that quotation marks on the command line be preceded by an escape character. The following are examples of how case-sensitivity can be preserved in the different Export modes.

· In command-line mode:

TABLES='\"Emp\"'

· In interactive mode:

Table(T) to be exported: "Emp"

· In parameter file mode:

TABLES='"Emp"'

· Table names specified on the command line cannot include a pound (#) sign, unless the table name is enclosed in quotation marks. Similarly, in the parameter file, if a table name includes a pound (#) sign, the Export utility interprets the rest of the line as a comment, unless the table name is enclosed in quotation marks.

For example, if the parameter file contains the following line, Export interprets everything on the line after emp# as a comment and does not export the tables dept and mydata:

TABLES=(emp#, dept, mydata)

However, given the following line, the Export utility exports all three tables because emp# is enclosed in quotation marks:

TABLES=("emp#", dept, mydata)

Note:

Some operating systems require single quotation marks rather than double quotation marks, or the reverse; see your Oracle operating system-specific documentation. Different operating systems also have other restrictions on table naming.

For example, the UNIX C shell attaches a special meaning to a dollar sign ($) or pound sign (#) (or certain other special characters). You must use escape characters to get such characters in the name past the shell and into Export.

For a TABLES parameter that specifies multiple schema.tablename:(sub)partition_name arguments, Export attempts to purge duplicates before processing the list of objects.

TABLESPACES

Default: none

The TABLESPACES parameter specifies that all tables in the tablespace be exported to the Export dump file. This includes all tables contained in the list of tablespaces and all tables that have a partition located in the list of tablespaces. Indexes are exported with their tables, regardless of where the index is stored.

You must have the EXP_FULL_DATABASE role to use TABLESPACES to export all tables in the tablespace.

When TABLESPACES is used in conjunction with TRANSPORT_TABLESPACE=y, you can specify a limited list of tablespaces to be exported from the database to the export file.

TRANSPORT_TABLESPACE

Default: n

When specified as y, this parameter enables the export of transportable tablespace metadata.

· The user's guide for your Oracle Net protocol for information about specifying the @connect_string for Oracle Net

VOLSIZE

Specifies the maximum number of bytes in an export file on each volume of tape.

The VOLSIZE parameter has a maximum value equal to the maximum value that can be stored in 64 bits. See your Oracle operating system-specific documentation for more information.

The VOLSIZE value can be specified as a number followed by KB (number of kilobytes). For example, VOLSIZE=2KB is the same as VOLSIZE=2048. Similarly, MB specifies megabytes (1024 * 1024) and GB specifies gigabytes (1024**3). B remains the shorthand for bytes; the number is not multiplied to get the final file size (VOLSIZE=2048B is the same as VOLSIZE=2048).

Parameter Interactions

Certain parameters can conflict with each other. For example, because specifying TABLES can conflict with an OWNER specification, the following command causes Export to terminate with an error:

exp SYSTEM/password OWNER=jones TABLES=scott.emp

Similarly, OWNER and TABLES conflict with FULL=y.

Example Export Sessions

This section provides examples of the following types of Export sessions:

· Example Export Session in Full Database Mode

· Example Export Session in User Mode

· Example Export Sessions in Table Mode

· Example Export Session Using Partition-Level Export

In each example, you are shown how to use both the command-line method and the parameter file method.

Example Export Session in Full Database Mode

Only users with the DBA role or the EXP_FULL_DATABASE role can export in full database mode. In this example, an entire database is exported to the file dba.dmp with all GRANTS and all data.

Parameter File Method

> exp SYSTEM/password PARFILE=params.dat

The params.dat file contains the following information:

FILE=dba.dmp

GRANTS=y

FULL=y

ROWS=y

Command-Line Method

> exp SYSTEM/password FULL=y FILE=dba.dmp GRANTS=y ROWS=y

Example Export Session in User Mode

User mode exports can be used to back up one or more database users. For example, a DBA may want to back up the tables of deleted users for a period of time. User mode is also appropriate for users who want to back up their own data or who want to move objects from one owner to another. In this example, user scott is exporting his own tables.

Parameter File Method

> exp scott/tiger PARFILE=params.dat

The params.dat file contains the following information:

FILE=scott.dmp

OWNER=scott

GRANTS=y

ROWS=y

COMPRESS=y

Command-Line Method

> exp scott/tiger FILE=scott.dmp OWNER=scott GRANTS=y ROWS=y COMPRESS=y

Example Export Sessions in Table Mode

In table mode, you can export table data or the table definitions. (If no rows are exported, the CREATE TABLE statement is placed in the export file, with grants and indexes, if they are specified.)

A user with the EXP_FULL_DATABASE role can use table mode to export tables from any user's schema by specifying TABLES=schemaname.tablename.

If schemaname is not specified, Export defaults to the previous schema name from which an object was exported. If there is not a previous object, Export defaults to the exporter's schema. In the following example, Export defaults to the SYSTEM schema for table a and to scott for table c:

> exp SYSTEM/password TABLES=(a, scott.b, c, mary.d)

A user with the EXP_FULL_DATABASE role can also export dependent objects that are owned by other users. A nonprivileged user can export only dependent objects for the specified tables that the user owns.

Exports in table mode do not include cluster definitions. As a result, the data is exported as unclustered tables. Thus, you can use table mode to uncluster tables.

Example 1: DBA Exporting Tables for Two Users

In this example, a DBA exports specified tables for two users.

Parameter File Method

> exp SYSTEM/password PARFILE=params.dat

The params.dat file contains the following information:

FILE=expdat.dmp

TABLES=(scott.emp,blake.dept)

GRANTS=y

INDEXES=y

Command-Line Method

> exp SYSTEM/password FILE=expdat.dmp TABLES=(scott.emp,blake.dept) GRANTS=y-

INDEXES=y

Example 2: User Exports Tables That He Owns

In this example, user blake exports selected tables that he owns.

Parameter File Method

> exp blake/paper PARFILE=params.dat

The params.dat file contains the following information:

FILE=blake.dmp

TABLES=(dept,manager)

ROWS=y

COMPRESS=y

Command-Line Method

> exp blake/paper FILE=blake.dmp TABLES=(dept, manager) ROWS=y COMPRESS=y

Example 3: Using Pattern Matching to Export Various Tables

In this example, pattern matching is used to export various tables for users scott and blake.

Parameter File Method

> exp SYSTEM/password PARFILE=params.dat

The params.dat file contains the following information:

FILE=misc.dmp

TABLES=(scott.%P%,blake.%,scott.%S%)

Command-Line Method

> exp SYSTEM/password FILE=misc.dmp TABLES=(scott.%P%,blake.%,scott.%S%)

Example Export Session Using Partition-Level Export

In partition-level export, you can specify the partitions and subpartitions of a table that you want to export.

Example 1: Exporting a Table Without Specifying a Partition

Assume emp is a table that is partitioned on employee name. There are two partitions, m and z. As this example shows, if you export the table without specifying a partition, all of the partitions are exported.

Parameter File Method

> exp scott/tiger PARFILE=params.dat

The params.dat file contains the following:

TABLES=(emp)

ROWS=y

Command-Line Method

> exp scott/tiger TABLES=emp rows=y

Example 2: Exporting a Table with a Specified Partition

Assume emp is a table that is partitioned on employee name. There are two partitions, m and z. As this example shows, if you export the table and specify a partition, only the specified partition is exported.

Parameter File Method

> exp scott/tiger PARFILE=params.dat

The params.dat file contains the following:

TABLES=(emp:m)

ROWS=y

Command-Line Method

> exp scott/tiger TABLES=emp:m rows=y

Example 3: Exporting a Composite Partition

Assume emp is a partitioned table with two partitions, m and z. Table emp is partitioned using the composite method. Partition m has subpartitions sp1 and sp2, and partition z has subpartitions sp3 and sp4. As the example shows, if you export the composite partition m, all its subpartitions (sp1 and sp2) will be exported. If you export the table and specify a subpartition (sp4), only the specified subpartition is exported.

Parameter File Method

> exp scott/tiger PARFILE=params.dat

The params.dat file contains the following:

TABLES=(emp:m,emp:sp4)

ROWS=y

Command-Line Method

> exp scott/tiger TABLES=(emp:m, emp:sp4) ROWS=y

Restrictions

Keep in mind the following points when you use the interactive method:

· In user mode, Export prompts for all usernames to be included in the export before exporting any data. To indicate the end of the user list and begin the current Export session, press Enter.

· In table mode, if you do not specify a schema prefix, Export defaults to the exporter's schema or the schema containing the last table exported in the current session.

For example, if beth is a privileged user exporting in table mode, Export assumes that all tables are in the beth schema until another schema is specified. Only a privileged user (someone with the EXP_FULL_DATABASE role) can export tables in another user's schema.

· If you specify a null table list to the prompt "Table to be exported," the Export utility exits.

Warning, Error, and Completion Messages

This section describes the different types of messages issued by Export and how to save them in a log file.

Log File

You can capture all Export messages in a log file, either by using the LOG parameter (see LOG) or, for those systems that permit it, by redirecting the Export output to a file. The Export utility writes a log of detailed information about successful unloads and any errors that may occur. Refer to your Oracle operating system-specific documentation for information on redirecting output.

Warning Messages

Export does not terminate after recoverable errors. For example, if an error occurs while exporting a table, Export displays (or logs) an error message, skips to the next table, and continues processing. These recoverable errors are known as warnings.

Export also issues a warning whenever it encounters an invalid object.

For example, if a nonexistent table is specified as part of a table-mode export, the Export utility exports all other tables. Then it issues a warning and terminates successfully.

Nonrecoverable Error Messages

Some errors are nonrecoverable and terminate the Export session. These errors typically occur because of an internal problem or because a resource, such as memory, is not available or has been exhausted. For example, if the catexp.sql script is not executed, Export issues the following nonrecoverable error message:

EXP-00024: Export views not installed, please notify your DBA

Completion Messages

When an export completes without errors, Export displays the following message:

Export terminated successfully without warnings

If one or more recoverable errors occurs but Export is able to continue to completion, Export displays the following message:

Export terminated successfully with warnings

If a nonrecoverable error occurs, Export terminates immediately and displays the following message:

Export terminated unsuccessfully

Exit Codes for Inspection and Display

Export provides the results of an export operation immediately upon completion. Depending on the platform, Export may report the outcome in a process exit code as well as recording the results in the log file. This enables you to check the outcome from the command line or script. Table 1-5 shows the exit codes that get returned for various results.

Table 1-5 Exit Codes for Export

Result	Exit Code
Export terminated successfully without warnings	EX_SUCC
Export terminated successfully with warnings	EX_OKWARN
Export terminated unsuccessfully	EX_FAIL

For UNIX, the exit codes are as follows:

EX_SUCC 0

EX_OKWARN 0

EX_FAIL 1

Conventional Path Export Versus Direct Path Export

Export provides two methods for exporting table data:

· Conventional path Export

· Direct path Export

Conventional path Export uses the SQL SELECT statement to extract data from tables. Data is read from disk into a buffer cache, and rows are transferred to the evaluating buffer. The data, after passing expression evaluation, is transferred to the Export client, which then writes the data into the export file.

Direct path Export is much faster than conventional path Export because data is read from disk into the buffer cache and rows are transferred directly to the Export client. The evaluating buffer is bypassed. The data is already in the format that Export expects, thus avoiding unnecessary data conversion. The data is transferred to the Export client, which then writes the data into the export file.

Invoking a Direct Path Export

To invoke a direct path Export, you must use either the command-line method or a parameter file. You cannot invoke a direct path Export using the interactive method.

To use direct path Export, specify the DIRECT=y parameter on the command line or in the parameter file. The default is DIRECT=n, which extracts the table data using the conventional path.

Additionally, be aware that the Export parameter BUFFER applies only to conventional path Exports. For direct path Export, use the RECORDLENGTH parameter to specify the size of the buffer that Export uses for writing to the export file.

Security Considerations for Direct Path Exports

Virtual Private Database (VPD) and Oracle Label Security are not enforced during direct path Exports.

The following users are exempt from Virtual Private Database and Oracle Label Security enforcement regardless of the export mode, application, or utility used to extract data from the database:

· The database user SYS

· Database users granted the Oracle9i EXEMPT ACCESS POLICY privilege, either directly or through a database role

This means that any user who is granted the EXEMPT ACCESS POLICY privilege is completely exempt from enforcement of VPD and Oracle Label Security. This is a powerful privilege and should be carefully managed. This privilege does not affect the enforcement of traditional object privileges such as SELECT, INSERT, UPDATE, and DELETE. These privileges are enforced even if a user has been granted the EXEMPT ACCESS POLICY privilege.

Performance Issues for Direct Path Exports

You may be able to improve performance by increasing the value of the RECORDLENGTH parameter when you invoke a direct path Export. Your exact performance gain depends upon the following factors:

· DB_BLOCK_SIZE

· The types of columns in your table

· Your I/O layout (The drive receiving the export file should be separate from the disk drive where the database files reside.)

The following values are generally recommended for RECORDLENGTH:

· Multiples of the file system I/O block size

· Multiples of DB_BLOCK_SIZE

Network Considerations

This section describes factors to take into account when you use Export and Import across a network.

Transporting Export Files Across a Network

Because the export file is in binary format, use a protocol that supports binary transfers to prevent corruption of the file when you transfer it across a network. For example, use FTP or a similar file transfer protocol to transmit the file in binary mode. Transmitting export files in character mode causes errors when the file is imported.

Exporting and Importing with Oracle Net

With Oracle Net, you can perform exports and imports over a network. For example, if you run Export locally, you can write data from a remote Oracle database into a local export file. If you run Import locally, you can read data into a remote Oracle database.

To use Import with Oracle Net, include the connection qualifier string @connect_string when entering the username/password in the exp or imp command. For the exact syntax of this clause, see the user's guide for your Oracle Net protocol.

Character Set and Globalization Support Considerations

This section describes the behavior of Export and Import with respect to globalization support.

Character Set Conversion

The Export utility always exports user data, including Unicode data, in the character sets of the Export server. The character sets are specified at database creation.

The Import utility automatically converts the data to the character sets of the Import server.

Some 8-bit characters can be lost (that is, converted to 7-bit equivalents) when you import an 8-bit character set export file. This occurs if the client system has a native 7-bit character set or if the NLS_LANG operating system environment variable is set to a 7-bit character set. Most often, you notice that accented characters lose their accent mark.

Both Export and Import provide descriptions of any required character set conversion before exporting or importing the data.

Note:

Data definition language (DDL), such as a CREATE TABLE command, is exported in the client character set.

Effect of Character Set Sorting Order on Conversions

If the export character set has a different sorting order than the import character set, then tables that are partitioned on character columns may yield unpredictable results. For example, consider the following table definition, which is produced on a database having an ASCII character set:

CREATE TABLE partlist

(

part VARCHAR2(10),

partno NUMBER(2)

)

PARTITION BY RANGE (part)

(

PARTITION part_low VALUES LESS THAN ('Z')

TABLESPACE tbs_1,

PARTITION part_mid VALUES LESS THAN ('z')

TABLESPACE tbs_2,

PARTITION part_high VALUES LESS THAN (MAXVALUE)

TABLESPACE tbs_3

);

This partitioning scheme makes sense because z comes after Z in ASCII character sets.

When this table is imported into a database based upon an EBCDIC character set, all of the rows in the part_mid partition will migrate to the part_low partition because z comes before Z in EBCDIC character sets. To obtain the desired results, the owner of partlist must repartition the table following the import.../../server.920/a96529/toc.htm

Considerations When Exporting Database Objects

The following sections describe points you should consider when you export particular database objects.

Exporting Sequences

If transactions continue to access sequence numbers during an export, sequence numbers can be skipped. The best way to ensure that sequence numbers are not skipped is to ensure that the sequences are not accessed during the export.

Sequence numbers can be skipped only when cached sequence numbers are in use. When a cache of sequence numbers has been allocated, they are available for use in the current database. The exported value is the next sequence number (after the cached values). Sequence numbers that are cached, but unused, are lost when the sequence is imported.

Exporting LONG and LOB Datatypes

On export, LONG datatypes are fetched in sections. However, enough memory must be available to hold all of the contents of each row, including the LONG data.

LONG columns can be up to 2 gigabytes in length.

All data in a LOB column does not need to be held in memory at the same time. LOB data is loaded and unloaded in sections.

Exporting Foreign Function Libraries

The contents of foreign function libraries are not included in the export file. Instead, only the library specification (name, location) is included in full database and user mode export. You must move the library's executable files and update the library specification if the database is moved to a new location.

Exporting Offline Bitmapped Tablespaces

If the data you are exporting contains offline bitmapped tablespaces, Export will not be able to export the complete tablespace definition and will display an error message. You can still import the data; however, you must first create the offline bitmapped tablespaces before importing to prevent DDL commands that may reference the missing tablespaces from failing.

Exporting Directory Aliases

Directory alias definitions are included only in a full database mode Export. To move a database to a new location, the database administrator must update the directory aliases to point to the new location.

Directory aliases are not included in user or table mode Export. Therefore, you must ensure that the directory alias has been created on the target system before the directory alias is used.

Exporting BFILE Columns and Attributes

The export file does not hold the contents of external files referenced by BFILE columns or attributes. Instead, only the names and directory aliases for files are copied on Export and restored on Import. If you move the database to a location where the old directories cannot be used to access the included files, the database administrator (DBA) must move the directories containing the specified files to a new location where they can be accessed.

External Tables

The contents of external tables are not included in the export file. Instead, only the table specification (name, location) is included in full database and user mode export. You must manually move the external data and update the table specification if the database is moved to a new location.

Exporting Object Type Definitions

In all Export modes, the Export utility includes information about object type definitions used by the tables being exported. The information, including object name, object identifier, and object geometry, is needed to verify that the object type on the target system is consistent with the object instances contained in the export file. This ensures that the object types needed by a table are created with the same object identifier at import time.

Note, however, that in table, user, and tablespace mode, the export file does not include a full object type definition needed by a table if the user running Export does not have execute access to the object type. In this case, only enough information is written to verify that the type exists, with the same object identifier and the same geometry, on the import target system.

The user must ensure that the proper type definitions exist on the target system, either by working with the DBA to create them, or by importing them from full database or user mode exports performed by the DBA.

It is important to perform a full database mode export regularly to preserve all object type definitions. Alternatively, if object type definitions from different schemas are used, the DBA should perform a user mode export of the appropriate set of users. For example, if table1 belonging to user scott contains a column on blake's type type1, the DBA should perform a user mode export of both blake and scott to preserve the type definitions needed by the table.

Exporting Nested Tables

Inner nested table data is exported whenever the outer containing table is exported. Although inner nested tables can be named, they cannot be exported individually.

Exporting Advanced Queue (AQ) Tables

Queues are implemented on tables. The export and import of queues constitutes the export and import of the underlying queue tables and related dictionary tables. You can export and import queues only at queue table granularity.

When you export a queue table, both the table definition information and queue data are exported. Because the queue table data is exported as well as the table definition, the user is responsible for maintaining application-level data integrity when queue table data is imported.

Exporting Synonyms

You should be cautious when exporting compiled objects that reference a name used as a synonym and as another object. Exporting and importing these objects will force a recompilation that could result in changes to the object definitions.

The following example helps to illustrate this problem:

CREATE PUBLIC SYNONYM emp FOR scott.emp;

CONNECT blake/paper;

CREATE TRIGGER t_emp BEFORE INSERT ON emp BEGIN NULL; END;

CREATE VIEW emp AS SELECT * FROM dual;

If the database in the preceding example were exported, the reference to emp in the trigger would refer to blake's view rather than to scott's table. This would cause an error when Import tried to reestablish the t_emp trigger.

Possible Export Errors Related to Java Synonyms

If an export operation attempts to export a synonym named DBMS_JAVA when there is no corresponding DBMS_JAVA package or when Java is either not loaded or loaded incorrectly, the export will terminate unsuccessfully. The error messages that are generated include, but are not limited to, the following: EXP-00008, ORA-00904, and ORA-29516.

If Java is enabled, make sure that both the DBMS_JAVA synonym and DBMS_JAVA package are created and valid before rerunning the export.

If Java is not enabled, remove Java-related objects before rerunning the export.

Support for Fine-Grained Access Control

You can export tables with fine-grained access control policies enabled. When doing so, consider the following:

· The user who imports from an export file containing such tables must have the appropriate privileges (specifically, the EXECUTE privilege on the DBMS_RLS package so that the tables' security policies can be reinstated). If a user without the correct privileges attempts to export a table with fine-grained access policies enabled, only those rows that the exporter is privileged to read will be exported.

· If fine-grained access control is enabled on a SELECT statement, then conventional path Export may not export the entire table because fine-grained access may rewrite the query.

· Only user SYS, or a user with the EXPORT_FULL_DATABASE role enabled or who has been granted EXEMPT ACCESS POLICY, can perform direct path Exports on tables having fine-grained access control.

Transportable Tablespaces

The transportable tablespace feature enables you to move a set of tablespaces from one Oracle database to another.

After copying the datafiles and exporting the metadata, you can optionally put the tablespaces in read/write mode.

Export provides the following parameters to enable export of transportable tablespace metadata.

· TABLESPACES

· TRANSPORT_TABLESPACE

Using Export and Import to Partition a Database Migration

When you use the Export and Import utilities to migrate a large database, it may be more efficient to partition the migration into multiple export and import jobs. If you decide to partition the migration, be aware of the following advantages and disadvantages.

Advantages of Partitioning a Migration

Partitioning a migration has the following advantages:

· Time required for the migration may be reduced because many of the subjobs can be run in parallel.

· The import can start as soon as the first export subjob completes, rather than waiting for the entire export to complete.

Disadvantages of Partitioning a Migration

Partitioning a migration has the following disadvantages:

· The export and import processes become more complex.

· Support of cross-schema references for certain types of objects may be compromised. For example, if a schema contains a table with a foreign key constraint against a table in a different schema, you may not have the required parent records when you import the table into the dependent schema.

How to Use Export and Import to Partition a Database Migration

To perform a database migration in a partitioned manner, take the following steps:

For all top-level metadata in the database, issue the following commands:

exp dba/password FILE=full FULL=y CONSTRAINTS=n TRIGGERS=n ROWS=n INDEXES=n

imp dba/password FILE=full FULL=y

For each scheman in the database, issue the following commands:

exp dba/password OWNER=scheman FILE=scheman

imp dba/password FILE=scheman FROMUSER=scheman TOUSER=scheman IGNORE=y

All exports can be done in parallel. When the import of full.dmp completes, all remaining imports can also be done in parallel.

Using Different Releases and Versions of Export

This section describes compatibility issues that relate to using different releases of Export and the Oracle database server.

Whenever you are moving data between different releases of the Oracle database server, the following basic rules apply:

· The Import utility and the database to which data is being imported (the target database) must be the same version.

· The version of the Export utility must be equal to the lowest version of the source or target database.

For example, to create an export file for an import into a higher release database, use a version of the Export utility that is equal to the source database. Conversely, to create an export file for an import into a lower release database, use a version of the Export utility that is equal to the version of the target database. The following information is for specific versions:

· When you create an Oracle version 6 export file from an Oracle7 database by running the Oracle version 6 Export utility against the Oracle7 database server, you must first run the catexp6.sql script on the Oracle7 database. This script creates the export views that make the database look, to Export, like an Oracle version 6 database.

· When you create an Oracle7 export file from an Oracle8i database by running the Oracle7 Export utility against the Oracle8i database, you must first run the catexp7.sql script on the Oracle8i database. This script creates the export views that make the database look, to Export, like an Oracle8i database.

Restrictions When Using Different Releases and Versions of Export and Import

The following restrictions apply when you are using different releases of Export and Import:

· Export dump files can be read only by the Import utility because they are stored in a special binary format.

· Any export dump file can be imported into a higher release of the Oracle database server.

· The Import utility can read export dump files created by Export release 5.1.22 and higher.

· The Import utility cannot read export dump files created by the Export utility of a higher maintenance release or version. For example, a release 8.1 export dump file cannot be imported by a release 8.0 Import utility, and a version 8 export dump file cannot be imported by a version 7 Import utility.

· The Oracle version 6 (or earlier) Export utility cannot be used against an Oracle8 or higher database.

· Whenever a lower version of the Export utility runs with a higher version of the Oracle database server, categories of database objects that did not exist in the lower version are excluded from the export. For example, partitioned tables did not exist in the Oracle database server version 7. So, if you need to move a version 8 partitioned table to a version 7 database, you must first reorganize the table into a nonpartitioned table.

· Export files generated by Oracle9i Export, either direct path or conventional path, are incompatible with earlier releases of Import and can be imported only with Oracle9i Import. When backward compatibility is an issue, use the earlier release or version of the Export utility against the Oracle9i database.

Examples of Using Different Releases of Export and Import

Creating Oracle Release 8.0 Export Files from an Oracle9i Database

You do not need to take any special steps to create an Oracle release 8.0 export file from an Oracle9i database. However, the following features are not supported when you use Export release 8.0 on an Oracle9i database:

· Export does not export rows from tables containing objects and LOBs when you have specified a direct path load (DIRECT=y).

· Export does not export dimensions.

· Functional and domain indexes are not exported.

· Secondary objects (tables, indexes, sequences, and so on, created in support of a domain index) are not exported.

· Views, procedures, functions, packages, type bodies, and types containing references to new Oracle9i features may not compile.

· Objects whose DDL is implemented as a stored procedure rather than SQL are not exported.

· Triggers whose action is a CALL statement are not exported.

· Tables containing logical ROWID columns, primary key refs, or user-defined OID columns will not be exported.

· Temporary tables are not exported.

· Index-organized tables (IOTs) revert to an uncompressed state.

· Partitioned IOTs lose their partitioning information.

· Index types and operators are not exported.

· Bitmapped, temporary, and UNDO tablespaces are not exported.

· Java sources, classes, and resources are not exported.

· Varying-width CLOBs, collection enhancements, and LOB-storage clauses for VARRAY columns or nested table enhancements are not exported.

· Fine-grained access control policies are not preserved.

· External tables are not exported.

Possible Errors When Using Different Releases and Versions

This section briefly discusses some of the error messages you might receive if incompatible releases or versions of the Export utility and the Oracle database server are used.

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