Context
gds is used to import and export data of GaussDB(DWS). For details, see "Importing Data" and "Exporting Data" in the Developer Guide.
Syntax
gds [ OPTION ] -d DIRECTORY
The -d and -H parameters are mandatory and option is optional. gds provides the file data of DIRECTORY for GaussDB(DWS) to access.
Before starting GDS, you need to ensure that your GDS version is consistent with the database version. Otherwise, the database will display an error message and terminate the import and export operations. You can view the specific version through the -V parameter.
Parameter Description
- -d dir
Sets the directory of the data file to be imported. If the GDS process permission is sufficient, the directory specified by -d is automatically created.
- -p ip:port
Sets the IP address and port for listening to GDS.
Value range of the IP address: The IP address must be valid.
Default value: 127.0.0.1
Value range of the listening port is a positive integer ranging from 1024 to 65535.
Default value of port: 8098
- -l log_file
Sets the log file. This feature adds the function of automatical log splitting. After the -R parameter is set, GDS generates a new file based on the set value to prevent a single log file from being too large.
Generation rule: By default, GDS identifies only files with the .log extension name and generates new log files.
For example, if -l is set to gds.log and -R is set to 20 MB, a gds-2020-01-17_115425.log file will be created when the size of gds.log reaches 20 MB.
If the log file name specified by -l does not end with .log, for example, gds.log.txt, the name of the new log file is gds.log-2020-01-19_122739.txt.
When GDS is started, it checks whether the log file specified by -l exists. If the log file exists, a new log file is generated based on the current date and time, and the original log file is not overwritten.
If the number of GDS process logs in the current directory exceeds the value of --log-filecount, old logs will be reclaimed. To save a large number of logs, you are advised to set an independent directory for each GDS process and increase the value of --log-filecount.
- -H address_string
Sets the hosts that can be connected to the GDS. This parameter must be the CIDR format. Only the Linux OS is supported. If multiple network segments need to be configured, use commas (,) to separate them. For example, -H 10.10.0.0/24, 10.10.5.0/24.
- -e dir
Sets the saving path of error logs generated when data is imported.
Default value: data file directory
- -E size
Sets the upper threshold of error logs generated when data is imported.
Value range: 0 < size < 1 TB. The value must be a positive integer plus the unit. The unit can be KB, MB, or GB.
- -S size
Sets the upper limit of the exported file size.
Value range: 1 MB < size < 100 TB. The value must be a positive integer plus the unit. The unit can be KB, MB, or GB. If KB is used, the value must be greater than 1,024 KB.
- -R size
Sets the maximum size of a single GDS log file specified by -l.
Value range: 1 MB < size < 100 TB. The value must be a positive integer plus the unit. The unit can be KB, MB, or GB. If KB is used, the value must be greater than 1,024 KB.
Default value: 16 MB
- -t worker_num
Sets the number of concurrent imported and exported working threads.
Value range: The value is a positive integer ranging between 0 and 200 (included).
Default value: 8
Recommended value: 2 x CPU cores in the common file import and export scenario; in the pipe file import and export scenario, set the value to 64.
If a large number of pipe files are imported and exported concurrently, the value of this parameter must be greater than or equal to the number of concurrent services.
- -s status_file
Sets the status file. This parameter supports the Linux system only.
- -D
- -r
Recursively traverses files in a directory (subdirectories in the foreign table directory) and recursively reads all files with the same name in the directory specified by location. Only the Linux system is supported.
- -h
- --enable-ssl
Uses the SSL authentication mode to communicate with clusters.
- --ssl-dir Cert_file
Sets the path for storing the authentication certificates when the SSL authentication mode is used.
- --debug-level
Sets the debug log level of the GDS to control the output of GDS debug logs.
Value range: 0, 1, and 2
- 0: Only the file list related to log import and export is printed. If the log volume is small, set the parameter to this value only when the system is at normal state.
- 1: All the log information is printed, including the connection information, session switch information, and statistics on each node.
- 2: Detailed interaction logs and their status are printed to generate a huge number of debug logs to help identify the fault causes. You are advised to set the parameter to this value only during troubleshooting.
Default value: 0
- --log-filecount
Specifies the maximum number of log files that can be retained. When the number of log files exceeds the value of this parameter, the latest created log files are retained.
Value range: 5<=log-filecount<=1024 (positive integer)
Default value: 50
- --pipe-timeout
Sets the timeout period for GDS to wait for operating a pipe.
- This parameter is used to prevent the following situation: One end of the pipe file is not read or written for a long time due to human or program problems. As a result, the read or write operation on the other end of the pipe is hung.
- This parameter does not indicate the maximum duration of a data import or export task. It indicates the maximum timeout duration of each read, open, or write operation on the pipe. If the timeout duration exceeds the value of --pipe-timeout, an error is reported to the frontend.
Value range: greater than 1s Use a positive integer with the time unit, seconds (s), minutes (m), or hours (h). Example: 3600s, 60m, or 1h, indicating one hour.
Default value: 1h/60m/3600s
- --pipe-size
Specifies the size of the GDS pipe file to be imported or exported.
Value range: greater than 1K
Default value: maximum value allowed by the operating system. You can run the cat /proc/sys/fs/pipe-max-size command to view the default value.
This parameter can be used only when the Linux kernel version is 2.6.35 or later.
Examples
Data file is saved in the /data directory, the IP address is 192.168.0.90, and the listening port number is 5000.
gds -d /data/ -p 192.168.0.90:5000 -H 10.10.0.1/24
Data file is saved in the subdirectory of the /data directory, the IP address is 192.168.0.90, and the listening port number is 5000.
gds -d /data/ -p 192.168.0.90:5000 -H 10.10.0.1/24 -r
Data file is saved in the /data directory, the IP address is 192.168.0.90, and the listening port number is 5000 which is running on the backend. The log file is saved in the /log/gds_log.txt file, and the specified number of the concurrently imported working threads is 32.
gds -d /data/ -p 192.168.0.90:5000 -H 10.10.0.1/24 -l /log/gds_log.txt -D -t 32
Data file is saved in the /data directory, the IP address is 192.168.0.90, and the listening port number is 5000. Only the IP address of 10.10.0.* can be connected.
gds -d /data/ -p 192.168.0.90:5000 -H 10.10.0.1/24
Data files are stored in the /data/ directory, the IP address of the directory is 192.168.0.90, and the listening port number is 5000. Only the node whose IP address is 10.10.0.* can be connected to. The node communicates with the cluster using the SSL authentication mode, and the certificate files are stored in the /certfiles/ directory.
gds -d /data/ -p 192.168.0.90:5000 -H 10.10.0.1/24 --enable-ssl --ssl-dir /certfiles/
- One GDS provides the import and export services for one cluster only at a time.
- For security purpose, specify the IP address and the listening port using -p.
- The certificate file includes the root certificate cacert.pem, level-2 certificate file client.crt, and private key file client.key.
- The password protection files client.key.rand and client.key.cipher are used when the system loading certificates.