Spatial data backup and restoration policies in ArcSDE

With the increasing requirements of GIS application systems in terms of complexity, integration, and concurrency, the amount of space data required by the system is rapidly increasing. At the same time, users' demands for concurrent access to spatial data are becoming increasingly prominent. The traditional file storage and representation of spatial data methods obviously cannot meet these needs. Because of the powerful advantages of ArcSDE, such as massive data storage, multi-user concurrent access, version management, and long transaction processing, ArcSDE is introduced into the GIS application system as a space data storage and management engine, it is becoming more and more common. As a space database engine, ArcSDE is a server-side product in the ArcGis 8.1 series of software and plays an important role in the data center in the entire product framework, it uses Oracle, DB2, SQL Server, Informix, and other relational databases in data storage, data integrity, and other advanced technical means, massive space data (including vector data and grid data) organically organized and managed to provide efficient and concurrent access to spatial data through its internal asynchronous buffering, Spatial indexing, and other advanced mechanisms.

In addition to storage space data and access, backup and recovery of space data is one of the most important tasks in space data management and an important way to ensure the security of space data. First, the spatial data itself is constantly updated and changed during the application process. Therefore, it is often necessary to back up different spatial data versions in different periods. Second, accidental damage to storage media can lead to serious space data loss. Therefore, you need to regularly back up the entire space data object completely. Third, sometimes necessary for adjustment, it is necessary to port and convert spatial data between different servers or even different database management systems.

In the era of file-based spatial data, the backup of spatial data is only the process of copying, backing up, and archiving files in the operating system. The restoration of spatial data is only a copy and overwriting operation; in the era of spatial databases based on ArcSDE and relational databases, the backup of spatial data is more dependent on the backup and recovery technologies of relational databases. Of course, the backup tools provided by ArcSDE cannot be lacking. According to the backup method and object, the backup and recovery of space data in ArcSDE can be divided into the following two types: backup and recovery of space data objects and backup and recovery of the overall space database.

1. backup and recovery of data objects in a specified space
This method is mainly used to back up specified spatial data objects, such as a layer and element class, some records that meet specific conditions, and even specific versions. The main method to implement this backup mode is to use the management tools provided by ArcSDE: sdeexport and sdeimport commands. They are located in % arcsdehome % bin. Sdeexport is used to back up space data from the ArcSDE server as a separate data file, and sdeimport is used to restore the data files backed up by sdeexport to the ArcSDE server.

The disadvantage of this method is that you cannot back up the complete spatial database at a time. However, the sdeexport and sdeimport tools can also be used to port spatial data between different relational database management systems (RDBMS.

1. Backup all records
Use the default sdeexport command, for example:
(1) back up the specified layer to the backup file
Sdeexport-o create-l dcxq, shape-f d: dcxq. exp-I jerry_oracle-u Sde-P SDE
That is, the specified layer "dcxq" in the ArcSDE for Oracle8i of jerry_oracle is backed up to the file D: dcxq. Exp by default.
(2) copy the backup file to the target server using the operating system command
(3) restore the backup file to the target RDBMS
Sdeimport-o create-l newdcxq, shape-f d: dcxq. exp-I jerry_sqlsvr-u Sde-P SDE
This operation restores the backup file to the SDE Service (ArcSDE for sqlserver) named jerry_sqlsvr with the layer name newdcxq.

2. Backup part of records
Add the-W parameter and a conditional selection expression to the sdeexport command, for example:
(1) Back up records that meet the conditions in the specified layer to the backup file
Sdeexport-o create-l dcxq, shape-f d: dcxq. exp-W xzqy =/'xuhui district/'-I jerry_oracle-u Sde-P SDE
It is to back up all the/"Xuhui District/" demographics in the specified layer "dcxq" in the SDE Service (ArcSDE for Oracle8i) named jerry_oracle to the file D: dcxq. Exp.
(2) copy the backup file to the target server using the operating system command
(3) restore the backup file to the target RDBMS
Sdeimport-o create-l xhdcxq, shape-f d: dcxq. exp-I jerry_sqlsvr-u Sde-P SDE
This operation restores the backup file to the SDE Service (ArcSDE for sqlserver) named jerry_sqlsvr with the layer name xhdcxq.

3. Back up specific data versions
Add the-V parameter and a version name to the sdeexport command, for example:
(1) Back up a specific version of the specified layer to the backup file
Sdeexport-o create-l dcxq, shape-f d: dcxq. exp-V verapr-I jerry_oracle-u Sde-P SDE
This operation backs up the verapr version of the specified layer "dcxq" in the SDE Service (ArcSDE for Oracle8i) named jerry_oracle to the file D: dcxq. Exp.
(2) copy the backup file to the target server using the operating system command
(3) restore the backup file to the target RDBMS
Sdeimport-o create-l aprdcxq, shape-f d: dcxq. exp-I jerry_sqlsvr-u Sde-P SDE
This operation restores the backup file to the SDE Service (ArcSDE for sqlserver) named jerry_sqlsvr with the layer name aprdcxq.

Ii. backup and recovery of the overall spatial database
The overall backup and recovery of the ArcSDE space database is, to a large extent, the backup and recovery of the database or database object in which it is located. Of course, the complete ArcSDE data backup should also include files such as dbtune. SDE, giomgr. defs, dbinit. SDE, and services. Sde.

There are many types of database backup and recovery. In different database management systems, they are even more different. Generally, it can be divided into static dump and dynamic dump. Static dump is a dump operation performed when no transaction is processed in the system. Therefore, this method must be a copy of data consistency. The advantage of static dump is that it is easy to operate and ensures data consistency, but its disadvantage is obvious. The dump operation can only be performed after the user transaction ends, and the new transaction can only be executed after the dump operation ends, therefore, the database availability is reduced. A dynamic dump refers to a dump operation that is performed concurrently with user transactions. During the dump, the database is allowed to perform access and modification operations. It does not have to wait until all running transactions are completed, nor will it affect the operation of new transactions, however, the data in the copy cannot be correct, valid, and complete. Therefore, log files are often created during the dynamic dump. The backup file and log file can restore the database to the correct state.

1. Oracle Database
(1) Two archive modes (archive mapobjectde)
Oracle has two archive modes: No archivelog and archivelog. Online log redo files are not archived for database operations in no archivelog mode (this mode is the default mode. When the storage medium is damaged, databases in the no archivelog mode can only be restored to the last backup point. Databases in archivelog mode can be restored to the point before the media is damaged by combining the last backup with the archived log redo file. Edit: GIS tutorial Network