What's New
Function Overview
Product Bulletin
- Product Notice
- Version Support Notes
Service Overview
- GaussDB(DWS) Infographics
- What Is GaussDB(DWS)?
- Data Warehouse Types
- Data Warehouse Flavors
- Advantages
- Application Scenarios
- Functions
- Concepts
- Related Services
- Security
- GaussDB(DWS) Permissions Management
- GaussDB(DWS) Access
- Restrictions
- Technical Support
- Service Quotas
- GaussDB(DWS) Technical Specifications
Billing
- GaussDB(DWS) Billing Overview
- Billing Modes
- Item
- Billing Examples
- Billing Mode Change
- Renewal
  - Overview
  - Manual Renewal
- Bills
- Arrears
- Stopping Billing
- Cost Management
- Billing FAQs
Getting Started
- Checkpoint Vehicle Analysis
- Supply Chain Requirement Analysis of a Company
- Operations Status Analysis of a Retail Department Store
- Creating a Time Series Table
- Best Practices of Hot and Cold Data Management
- Best Practices for Automatic Partition Management
- Creating a Cluster and Connecting to It
- Using CDM to Migrate MySQL Data to the GaussDB(DWS) Cluster
- Using DLI Flink Jobs to Write Kafka Data to GaussDB(DWS) in Real Time
- Basic SQL Operations
- Database Quick Start
- Getting Started with Common Practices
User Guide
- Using GaussDB(DWS)
- Preparations
- Creating a GaussDB(DWS) Cluster
- Connecting to a GaussDB(DWS) Cluster
- Creating a GaussDB(DWS) Database and User
- Migrating Service Data to a GaussDB(DWS) Cluster
  - Migrating Data to a GaussDB(DWS) Cluster Using GDS-Kafka
  - Data Source Management
- GaussDB(DWS) Cluster Data Security and Encryption
- GaussDB(DWS) Cluster Management
- GaussDB(DWS) Cluster O&M
Best Practices
- Import and Export
- Data Migration
- Data Analytics
- Decoupled Storage and Compute
  - DWS 3.0 Decoupled Storage and Compute Usage Suggestions and Performance Optimization
- Data Development
- Database Management
- Performance Tuning
  - Optimizing Table Structure Design to Enhance GaussDB(DWS) Query Performance
  - Analyzing SQL Statements That Are Being Executed to Handle GaussDB(DWS) Performance Issues
- Cluster Management
  - Binding Different Resource Pools to Two Types of Jobs to Balance Load for GaussDB(DWS)
  - Scaling Options for GaussDB(DWS) with a Coupled Storage-Compute Architecture
Data Migration and Synchronization
- Data Migration to GaussDB(DWS)
- Importing Data
- Full Database Migration
  - Using CDM to Migrate Data to GaussDB(DWS)
  - Using DSC to Migrate SQL Scripts
- Real-time Import
  - Using DRS to Import Data to GaussDB(DWS)
  - Real-time Data Import From Kafka GaussDB(DWS)
- Metadata Migration
  - Using gs_dump and gs_dumpall to Export Metadata
  - Using gs_restore to Import Data
- Exporting Data
- Other Operations
Developer Guide
- Standard data warehouse (9.1.0.x)
- Standard data warehouse (8.1.3.x)
- Hybrid Data Warehouse (9.1.0.x）
- Hybrid Data Warehouse (8.1.3.x）
- Historical Versions
SQL Syntax Reference
- SQL Syntax Reference (9.1.0.x)
- SQL Syntax Reference (8.1.3.x)
- Historical Versions
Performance Tuning
- Overview of Query Performance Optimization
- Query Execution Process
- SQL Execution Plan
- SQL Optimization Guide
- Optimization Cases
- SQL Execution Troubleshooting
- query_band Load Identification
- Common Performance Parameter Optimization Design
Tool Guide
- Overview
- Downloading Related Tools
- gsql
- Data Studio
- GDS
- DSC
- DataCheck
- DWS-Connector
- Server Tool
API Reference
- Before You Start
- API Overview
- Calling APIs
- Getting Started
- API Description
- Application Cases
  - Using Postman to Call the API for Creating a Cluster
  - Using Postman to Call the API for Creating a Snapshot
- Introduction
- Appendix
SDK Reference
- SDK Overview
FAQs
- Top FAQs
- Product Consulting
- Database Connections
- Data Migration
- Database Usage
- Cluster Management
- Account Permissions
- Database Performance
- Backup and Restoration
  1. Why Does It Take a Long Time to Create an Automated Snapshot in GaussDB(DWS)?
  2. Does a GaussDB(DWS) Snapshot Have the Same Function as an EVS Snapshot?
Troubleshooting
- Database Connections
- JDBC/ODBC
- Data Import and Export
- Database Parameter Modification
- Account/Permission/Password
- Cluster Performance
- Cluster Exceptions
  - The Disk Usage Alarm Is Frequently Generated
- Database Use
Videos
Performance White Paper
- Overview
- Test Result
  - TPC-H Single Query Test
  - TPC-DS Single Query Test
- Test Methods
- Appendixes
  - TPC-H Test Sets
  - TPC-DS Test Sets
Technical White Paper
- GaussDB(DWS)
- Platforms and Technical Specifications Supported by GaussDB(DWS)
  - Technical Specifications
- GaussDB(DWS) Core Technologies
- GaussDB(DWS) Tools
  - Client Tools
  - Database Monitoring Tool
- External APIs
Error Code Reference
- 8.2.0 and earlier versions
  - Management Console Error Code
  - Data Warehouse Service Error Codes
- 8.2.1 or later versions
Glossary
More Documents
- User Guide
- API Reference (ME-Abu Dhabi Region)
- Developer Guide (ME-Abu Dhabi Region)
- SQL Syntax Reference (ME-Abu Dhabi Region)
- Tool Guide (ME-Abu Dhabi Region)
- Error Code Reference (ME-Abu Dhabi Region)
  - Management Console Error Code
- User Guide (Paris Region)
- API Reference (Paris Region)
- Developer Guide (Paris Region)
- SQL Syntax Reference (Paris Region)
- Tool Guide (Paris Region)
- Error Code Reference (Paris Region)
  - Management Console Error Code
- User Guide (Kuala Lumpur Region)
- API Reference (Kuala Lumpur Region)
- Developer Guide (Kuala Lumpur Region)
- SQL Syntax Reference (Kuala Lumpur Region)
- Tool Guide (Kuala Lumpur Region)
- Error Code Reference (Kuala Lumpur Region)
  - Management Console Error Code
General Reference
- Glossary
- Service Level Agreement
- White Papers
- Endpoints
- Permissions

On this page

Show all

Help Center/ GaussDB(DWS)/ Data Migration and Synchronization/ Importing Data/ Using GDS to Import Data from a Remote Server/ Importing Data In Parallel Using GDS

Importing Data In Parallel Using GDS

Updated on 2024-05-07 GMT+08:00

View PDF

INSERT and COPY statements can be used only for serially importing a small volume of data. To import a large volume of data to GaussDB(DWS), you can use GDS to import data in parallel using a foreign table.

In the current GDS version, you can import data to databases from pipe files.

When the local disk space of the GDS user is insufficient, HDFS data can be directly written to the pipe file without occupying extra disk space.
To clean data before importing, you can compile a program as needed and write the data to be processed into a pipe file.
NOTE:
- The current version does not support data import through GDS in SSL mode. Do not use GDS in SSL mode.
- All pipe files mentioned in this section refer to named pipes on Linux.
- To ensure the correctness of data import or export using GDS, you need to import or export data in the same compatibility mode.
  For example, data imported or exported in MySQL compatibility mode can be exported or imported only in MySQL compatibility mode.

Overview

You can import data in parallel from the common file system (excluding HDFS) of a server to GaussDB(DWS).

Data files to be imported are specified based on the import policy and data formats set in a foreign table. Data is imported in parallel through multiple DNs from source data files to the database, which improves the overall data import performance. Figure 1 shows an example.

The CN only plans data import tasks and delivers the tasks to DNs. In this case, the CN is released to process other tasks.
In this way, the computing capacities and bandwidths of all the DNs are fully leveraged to import data, improving the import performance.

You can pre-process data (such as invalid character replacement and fault tolerance processing) by setting parameters in a foreign table.

Figure 1 Importing data in parallel

The concepts mentioned in the preceding figure are described as follows:

CN: coordinator of GaussDB(DWS). After receiving import SQL requests from an application or client, the CN plans import tasks and delivers the tasks to DNs.
DN (Datanode): data node of GaussDB(DWS). After receiving the import tasks delivered by the CN, DNs import data from the source data file to the target table in the database through a foreign table.
Source data file: a file that stores data to be imported.
Data server: a server that stores source data files. For security purposes, it is recommended that the data server and GaussDB(DWS) be on the same intranet.
Foreign table: a table that stores information, such as the source location, format, destination location, encoding format, and data delimiter of a source data file. It is used to associate source data files with the target table.
Target table: a table in the database. It can be a row-store table or column-store table. Data in the source data files will be imported to this table.

Parallel Import Using GDS

If a large volume of data is stored on multiple servers, deploy, configure, and start GDS on each server. Then, data on all the servers can be imported in parallel, as shown in Figure 2.
Figure 2 Parallel import from multiple data servers

NOTICE:

The number of GDS processes cannot exceed that of DNs. If multiple GDS processes are connected to one DN, some of the processes will probably become abnormal.
If data is stored on data servers, and both GaussDB(DWS) and the data servers have available I/O resources, you can use GDS for multi-thread concurrent import.
GDS determines the number of threads based on the number of concurrent import transactions. Even if multi-thread import is configured before GDS startup, the import of a single transaction will not be accelerated. By default, an INSERT statement is an import transaction.

Multi-thread concurrent import enables you to:

Fully use resources and improve the concurrent import efficiency when you import multiple tables to the database.
Speed up the import of a table with a large volume of data.
Table data is split into multiple data files, and multi-thread concurrent import is implemented by importing data using multiple foreign tables at the same time. Ensure that a data file can be read only by one foreign table.

Import Process

Figure 3 Concurrent import procedure of GDS

**Table 1** Process description
Procedure	Description
Prepare source data.	Prepare the source data files to be imported to the database and upload the files to the data server. For details, see Preparing Source Data.
Start GDS.	Install, configure, and enable GDS on the data server. For details, see Installing, Configuring, and Starting GDS.
Create a foreign table.	A foreign table is used to identify source files. The foreign table stores information, such as the source location, format, destination location, encoding format, and inter-data delimiter of a source data file. For details, see Creating a GDS Foreign Table.
Import data.	After creating the foreign table, run the INSERT statement to quickly import data to the target table. For details, see Importing Data.
Handle the error table.	If errors occur during parallel data import, handle errors based on the error information to ensure data integrity. For details, see Handling Import Errors.
Improve query efficiency.	After data is imported, run the ANALYZE statement to generate table statistics. The ANALYZE statement stores the statistics in the PG_STATISTIC system catalog. The execution plan generator uses the statistics to generate the most efficient query execution plan.
Stop GDS.	After data import is complete, log in to each data server and stop GDS. For details, see Stopping GDS.

Parent topic: Using GDS to Import Data from a Remote Server

Previous topic: Using GDS to Import Data from a Remote Server

Next topic: Preparing Source Data

Feedback

Was this page helpful?

Helpful Not helpful

Provide feedback

Thank you very much for your feedback. We will continue working to improve the documentation.See the reply and handling status in My Cloud VOC.

The system is busy. Please try again later.

Which of the following issues have you encountered?

Content is inconsistent with the product UI

Unclear descriptions

Lack of examples or code

Incorrect steps

Can't find what I need

Lack of best practices

Feedback (optional)

0/500

Select at least one type of issue, and enter your comments or suggestions.

Enter a maximum of 500 characters.

Submit Cancel

For any further questions, feel free to contact us through the chatbot.

Chatbot