Overview
GaussDB(DWS) provides gs_dump and gs_dumpall to export required database objects and related information. To migrate database information, you can use a tool to import the exported metadata to a target database. gs_dump exports a single database or its objects. gs_dumpall exports all databases or global objects in a cluster. For details, see Table 1.
Application Scenario |
Export Granularity |
Export Format |
Import Method |
---|---|---|---|
Exporting a single database |
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|
|
|
|||
Table-level export
|
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Exporting all databases in a cluster |
|
Plain text |
For details about how to import data files, see Using a gsql Meta-Command to Import Data. |
Global object export
|
gs_dump and gs_dumpall use -U to specify the user that performs the export. If the specified user does not have the required permission, data cannot be exported. In this case, you can set --role in the export command to the role that has the permission. Then, gs_dump or gs_dumpall uses the specified role to export data. See Table 1 for application scenarios and Data Export By a User Without Required Permissions for operation details.
gs_dump and gs_dumpall encrypt the exported data files. These files are decrypted before being imported to prevent data disclosure for higher database security.
When gs_dump or gs_dumpall is used to export data from a cluster, other users can still access (read data from and write data to) databases in the cluster.
gs_dump and gs_dumpall can export complete, consistent data. For example, if gs_dump is used to export database A or gs_dumpall is used to export all databases from a cluster at T1, data of database A or all databases in the cluster at that time point will be exported, and modifications on the databases after that time point will not be exported.
Obtain gs_dump and gs_dumpall by decompressing the gsql CLI client package.
Precautions
- Do not modify an exported file or its content. Otherwise, restoration may fail.
- For data consistency and integrity, gs_dump and gs_dumpall set a share lock for a table to be dumped. If a share lock has been set for the table in other transactions, gs_dump and gs_dumpall lock the table after the lock is released. If the table cannot be locked within the specified time, the dump fails. You can customize the timeout duration to wait for lock release by specifying the --lock-wait-timeout parameter.
- During an export, gs_dumpall reads all tables in a database. Therefore, you need to connect to the database as a cluster administrator to export a complete file. When you use gsql to import scripts, cluster administrator permissions are also required to add users and user groups, and create databases.
- By default, the definitions of all views in the GaussDB(DWS) database contain the prefix of table names or aliases (in tab.col format). Therefore, the definitions may be inconsistent with the original ones. As a result, the base table corresponding to the rebuilt view column is incorrect and an error is reported. However, this rarely happens. To prevent this problem, you are advised to set the GUC parameter behavior_compat_options to compat_display_ref_table when exporting view definitions, so the exported definitions are consistent with the original statements.
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