19 Original Export and Import

Running catexp.sql or catalog.sql

To use Export and Import, you must run the script catexp.sql or catalog.sql (which runs catexp.sql) after the database has been created or migrated to Oracle Database 10g.

The catexp.sql or catalog.sql script needs to be run only once on a database. The script performs the following tasks to prepare the database for export and import operations:

• Creates the necessary export and import views in the data dictionary

• Creates the EXP_FULL_DATABASE role

• Assigns all necessary privileges to the EXP_FULL_DATABASE and IMP_FULL_DATABASE roles

• Assigns EXP_FULL_DATABASE and IMP_FULL_DATABASE to the DBA role

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

Ensuring Sufficient Disk Space for Export Operations

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 for Export and Import Operations

To use Export and Import, you must have the CREATE SESSION privilege on an Oracle database. This privilege belongs to the CONNECT role established during database creation. To export tables owned by another user, you must have the EXP_FULL_DATABASE role enabled. This role is granted to all database administrators (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

You can perform an import operation even if you did not create the export file. However, keep in mind that if the export file was created by a user with the EXP_FULL_DATABASE role, then you must have the IMP_FULL_DATABASE role to import it. Both of these roles are typically assigned to database administrators (DBAs).

Invoking Export and Import 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 or Import as SYSDBA, except in the following situations:

• At the request of Oracle technical support

• When importing a transportable tablespace set

To invoke Export or Import as SYSDBA, use the following syntax (substitute exp for imp if you are using Export). Add any desired parameters or parameter filenames:

imp \'username/password AS SYSDBA\'

Optionally, you could also specify an instance name:

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

If either the username or password is omitted, you will be prompted you for it.

This example shows the entire connect string enclosed in quotation marks and backslashes. This is because the string, AS SYSDBA, contains a blank, a situation for which most operating systems require that the entire connect string be placed in quotation marks or marked as a literal by some method. Some operating systems also require that quotation marks on the command line be preceded by an escape character. In this example, backslashes are used as the escape character. If the backslashes were not present, the command-line parser that Export and Import use would not understand the quotation marks and would remove them.

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

or

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

The number of parameters cannot exceed the maximum length of a command line on the system. Note that the examples could use imp to invoke Import rather than exp to invoke Export.

Parameter Files

The information in this section applies to both Export and Import, but the examples show use of the Export command, exp.

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.dmp
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.

Interactive Mode

If you prefer to be prompted for the value of each parameter, you can use the following syntax to start Export (or Import, if you specify imp) in interactive mode:

exp username/password

Commonly used parameters are displayed with a request for you to enter a value. The command-line interactive method does not provide prompts for all functionality and is provided only for backward compatibility. If you want to use an interactive interface, Oracle recommends that you use the Oracle Enterprise Manager Export or Import Wizard.

If you do not specify a username/password combination on the command line, then you are prompted for this information.

Getting Online Help

Export and Import both provide online help. Enter exp help=y on the command line to invoke Export help or imp help=y to invoke Import help.

Importing Grants

To import the privileges that a user has granted to others, the user initiating the import must either own the objects or have object privileges with the WITH GRANT OPTION. Table 19-2 shows the required conditions for the authorizations to be valid on the target system.

Importing Objects into Other Schemas

To import objects into another user's schema, you must have the IMP_FULL_DATABASE role enabled.

Importing System Objects

To import system objects from a full database export file, the IMP_FULL_DATABASE role must be enabled. The parameter FULL specifies that the following system objects are included in the import when the export file is a full export:

• Profiles

• Public database links

• Public synonyms

• Roles

• Rollback segment definitions

• Resource costs

• Foreign function libraries

• Context objects

• System procedural objects

• System audit options

• System privileges

• Tablespace definitions

• Tablespace quotas

• User definitions

• Directory aliases

• System event triggers

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 JavaBeans (EJB) 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.

• The table compression attribute of tables and partitions is preserved during export and import. However, the import process does not use the direct path API, hence the data will not be stored in the compressed format when imported.

Manually Creating Tables Before Importing Data

When you choose to create tables manually before importing data into them from an export file, you should use either the same table definition previously used or a compatible format. For example, although you can increase the width of columns and change their order, you cannot do the following:

• Add NOT NULL columns

• Change the datatype of a column to an incompatible datatype (LONG to NUMBER, for example)

• Change the definition of object types used in a table

• Change DEFAULT column values

  Note:

  When tables are manually created before data is imported, the CREATE TABLE statement in the export dump file will fail because the table already exists. To avoid this failure and continue loading data into the table, set the Import parameter IGNORE=y. Otherwise, no data will be loaded into the table because of the table creation error.

Disabling Referential Constraints

In the normal import order, referential constraints are imported only after all tables are imported. This sequence prevents errors that could occur if a referential integrity constraint exists for data that has not yet been imported.

These errors can still occur when data is loaded into existing tables. For example, if table emp has a referential integrity constraint on the mgr column that verifies that the manager number exists in emp, a legitimate employee row might fail the referential integrity constraint if the manager's row has not yet been imported.

When such an error occurs, Import generates an error message, bypasses the failed row, and continues importing other rows in the table. You can disable constraints manually to avoid this.

Referential constraints between tables can also cause problems. For example, if the emp table appears before the dept table in the export file, but a referential check exists from the emp table into the dept table, some of the rows from the emp table may not be imported due to a referential constraint violation.

To prevent errors like these, you should disable referential integrity constraints when importing data into existing tables.

Manually Ordering the Import

When the constraints are reenabled after importing, the entire table is checked, which may take a long time for a large table. If the time required for that check is too long, it may be beneficial to order the import manually.

To do so, perform several imports from an export file instead of one. First, import tables that are the targets of referential checks. Then, import the tables that reference them. This option works if tables do not reference each other in a circular fashion, and if a table does not reference itself.

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 and Partition-Level Import

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

• Table-level Import: Imports all data from the specified tables in an export file.

• Partition-level Import: Imports only data from the specified source partitions or subpartitions.

You must set the parameter IGNORE=y when loading data into an existing table. See IGNORE for more information.

imp SYSTEM/password FILE=expdat.dmp FROMUSER=scott TABLES=b:py

imp scott/tiger FILE=expdat.dmp TABLES=(e:qc, e:qd) IGNORE=y

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 LOBs, LONG, BFILE, REF, ROWID, LOGICAL ROWID, or DATE are fetched one row at a time.

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

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.

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.

Table 19-4 shows a sequence of events by two users: user1 exports partitions in a table and user2 updates data in that table.

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 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.

  Note:

  Rollback segments will be deprecated in a future Oracle database release. Oracle recommends that you use automatic undo management instead.

  See Also:

  OBJECT_CONSISTENT

CONSTRAINTS

Default: y

Specifies whether or not the Export utility exports table constraints.

DIRECT

Default: n

Specifies the use of direct 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.

For information about direct path Exports, including security and performance considerations, see Invoking a Direct 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 individually for each table.

FILE

Default: expdat.dmp

Specifies the names of the export dump files. The default extension is .dmp, but you can specify any extension. Because Export supports multiple export files, you can specify multiple filenames to be used. For example:

exp scott/tiger FILE = dat1.dmp, dat2.dmp, dat3.dmp FILESIZE=2048

When Export reaches the value you have specified for the maximum FILESIZE, Export stops writing to the current file, opens another export file with the next name specified by the FILE parameter, and continues until complete or the maximum value of FILESIZE is again reached. If you do not specify sufficient export filenames to complete the export, Export will prompt you to provide additional filenames.

FILESIZE

Default: Data is written to one file until the maximum size, as specified in Table 19-5, 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.

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

Table 19-5 shows that the maximum size for dump files depends on the operating system you are using and on the release of the Oracle database that you are using.

The maximum value that can be stored in a file is dependent on your operating system. You should verify this maximum value in your Oracle operating system-specific documentation before specifying FILESIZE. You should also ensure that the file size you specify for Export is supported on the system on which Import will run.

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.

The following is an example of specifying an SCN. When the export is performed, the data will be consistent as of SCN 3482971.

> exp system/password FILE=exp.dmp FLASHBACK_SCN=3482971

FLASHBACK_TIME

Default: none

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

You can specify the time in any format that the DBMS_FLASHBACK.ENABLE_AT_TIME procedure accepts. This means that you can specify it in either of the following ways:

> exp system/password FILE=exp.dmp FLASHBACK_TIME="TIMESTAMP '2002-05-01 11:00:00'"

> exp system/password FILE=exp.dmp FLASHBACK_TIME="TO_TIMESTAMP('12-02-2001 14:35:00', 'DD-MM-YYYY HH24:MI:SS')"

Also, the old format, as shown in the following example, will continue to be accepted to ensure backward compatibility:

> exp system/password FILE=exp.dmp FLASHBACK_TIME="'2002-05-01 11:00:00'"

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 database administrator (DBA), multiple users can be listed.

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.

PARFILE

Default: none

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

QUERY

Default: none

This parameter enables 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.

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.

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.

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 terminated.

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

  Note:

  Specifying ROWS=n does not preclude saving the precalculated statistics in the export file. This enables you to tune plan generation for queries in a nonproduction database using statistics from a production database.

  See Also:

  Oracle Database Concepts

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, LBACSYS, 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.

TABLESPACES

Default: none

The TABLESPACES parameter specifies that all tables in the specified 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.

TRIGGERS

Default: y

Specifies whether or not the Export utility exports triggers.

TTS_FULL_CHECK

Default: n

When TTS_FULL_CHECK is set to y, Export verifies that a recovery set (set of tablespaces to be recovered) has no dependencies (specifically, IN pointers) on objects outside the recovery set, and the reverse.

USERID (username/password)

Default: none

Specifies the username/password (and optional connect string) of the user performing the export. If you omit the password, Export will prompt you for it.

USERID can also be:

username/password AS SYSDBA

or

username/password@instance AS SYSDBA

If you connect as user SYS, you must also specify AS SYSDBA in the connect string. Your operating system may require you to treat AS SYSDBA as a special string, in which case the entire string would be enclosed in quotation marks. See Invoking Export and Import for more information.

VOLSIZE

Default: none

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 on your platform.

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).

BUFFER

Default: operating system-dependent

The integer specified for BUFFER is the size, in bytes, of the buffer through which data rows are transferred.

BUFFER determines the number of rows in the array inserted by Import. The following formula gives an approximation of the buffer size that inserts a given array of rows:

buffer_size = rows_in_array * maximum_row_size

For tables containing LOBs or LONG, BFILE, REF, ROWID,UROWID, or TIMESTAMP columns, rows are inserted individually. The size of the buffer must be large enough to contain the entire row, except for LOB and LONG columns. If the buffer cannot hold the longest row in a table, Import attempts to allocate a larger buffer.

For DATE columns, two or more rows are inserted at once if the buffer is large enough.

COMMIT

Default: n

Specifies whether Import should commit after each array insert. By default, Import commits only after loading each table, and Import performs a rollback when an error occurs, before continuing with the next object.

If a table has nested table columns or attributes, the contents of the nested tables are imported as separate tables. Therefore, the contents of the nested tables are always committed in a transaction distinct from the transaction used to commit the outer table.

If COMMIT=n and a table is partitioned, each partition and subpartition in the Export file is imported in a separate transaction.

For tables containing LOBs, LONG, BFILE, REF, ROWID, or UROWID columns, array inserts are not done. If COMMIT=y, Import commits these tables after each row.