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This article introduces the relevant knowledge of "what is the exp export method in the database". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

1. Brief introduction of function

Export and import are common data migration tools (export / import) for oracle. This kind of migration uses logical migration. When actually doing the operation, the corresponding command for export/import is emp/imp (note lowercase).

two。 Migration conditions:

Exp&imp supports cross-version and cross-platform migration, as well as data migration of boast character sets. Most importantly, you don't need to make any preparations before the migration, just execute the exp/imp command and specify the relevant parameters to complete the export / import task.

3. View help

You can call up help information through the help=y command

[oracle@localhost U01] $exp help=y

Export: Release 11.2.0.4.0-Production on Tue Oct 23 02:43:45 2018

Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.

USERID must be the first parameter on the command line.

Keyword Description (Default) Keyword Description (Default)

USERID username/password FULL export entire file (N)

BUFFER size of data buffer OWNER list of owner usernames

FILE output files (EXPDAT.DMP) TABLES list of table names

COMPRESS import into one extent (Y) RECORDLENGTH length of IO record

GRANTS export grants (Y) INCTYPE incremental export type

INDEXES export indexes (Y) RECORD track incr. Export (Y)

DIRECT direct path (N) TRIGGERS export triggers (Y)

LOG log file of screen output STATISTICS analyze objects (ESTIMATE)

ROWS export data rows (Y) PARFILE parameter filename

CONSISTENT cross-table consistency (N) CONSTRAINTS export constraints (Y)

OBJECT_CONSISTENT transaction set to read only during object export (N)

FEEDBACK display progress every x rows (0)

FILESIZE maximum size of each dump file

FLASHBACK_SCN SCN used to set session snapshot back to

FLASHBACK_TIME time used to get the SCN closest to the specified time

QUERY select clause used to export a subset of a table

RESUMABLE suspend when a space related error is encountered (N)

RESUMABLE_NAME text string used to identify resumable statement

RESUMABLE_TIMEOUT wait time for RESUMABLE

TTS_FULL_CHECK perform full or partial dependency check for TTS

VOLSIZE number of bytes to write to each tape volume

TABLESPACES list of tablespaces to export

TRANSPORT_TABLESPACE export transportable tablespace metadata (N)

TEMPLATE template name which invokes iAS mode export

Export terminated successfully without warnings.

Note: the parameters supported when executing imp are similar to those mentioned above, but not exactly the same. You can view them by using the command imp help=y.

The processing mode of 4.Exp/imp

The Exp/imp tool supports 4 modes of operation when used:

(1) whole database mode: export and import the entire database, corresponding to FULL parameters

(2) tablespace schema: export and import object data in the specified tablespace, corresponding to tablespace parameters

(3) user mode: export and import user-owned objects, corresponding to owner parameters

(4) Table mode: export and import the specified table or partition table, corresponding to the tables parameter.

5.Exp calling mode

(1) call the command line

Direct execution of orders

For example: $exp scott/tiger tables=emp file=scott_emp.dmp log=scott_emp.log

(2) call by parameter file

First, edit a file

$vi scott_emp.dat

Tables=emp

Buffer=20480

Log=scott_emp.log

The second step, and then invoke this file when the command is executed

$exp scott/tiger parfile=scott_emp.dat

Example description of 6.Exp export

(1) Export the emp table of scott users

$exp scott/tiger tables=emp file=scott_emp.dmp log=scott_emp.log

(2) Export the data of empno > 100in the emp table of scott users

$exp scott/tiger tables=emp query= "'where empno > 100'" file=scott_emp100.dmp log=scott_emp100.log

(3) Export tables owned by scott users

$exp scott/tiger owner=scott file=scott_tables.dmp log=scott_tables.log

(4) full library export

$exp system/oracle full=y file=fulldb.dmp log=fulldb.log

7. Important parameter description

TABLES: specify which tables to export

QUERY: filter the data to be exported

SCHEMA: specify schema (written as user name)

LOG: specifies the name of the generated log file

FULL: when FULL=y, it represents the export of the whole library

FILESIZE: specifies the size of the exported single file

Index, constraint, Authorization

GRANTS: specifies the authorization information (access, operation permissions) of the object. Default is Y

INDEXES: specifies whether to export the index of the table, which defaults to Y

CONSTRAINTS: specifies whether to export constraints for the table, which defaults to Y

TRIGGERS: specifies whether to export table-related triggers. Default is Y

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