Help Center > > Developer Guide> Data Import> Import Modes

Import Modes

Updated at: Jul 15, 2020 GMT+08:00

DWS provides flexible methods ford importing data. You can import data from different sources to DWS. Each method has its own features, as listed in Table 1. You can select a method that meets your requirements.

Table 1 Import modes

Import Mode

Data Source

Description

Advantage

Importing Data from OBS in Parallel

OBS

You can import data in TXT, CSV, ORC, or CARBONDATA format from OBS to DWS for query, and can remotely read data from OBS.

It is recommended for DWS

This method features high performance and horizontal scaling.

Importing Data from MRS to a Cluster

MRS (HDFS)

Configure a DWS cluster to connect to an MRS cluster. In DWS, read data from the HDFS of MRS.

Using GDS to Import Data from a Remote Server

Servers (remote servers)

Use the GDS tool provided by DWS to import data from the remote server to DWS in parallel. Multiple DNs are used for the import. This mode is efficient and suitable for importing a large amount of data to the database.

Third-party ETL tool

Databases, NoSQL, file systems, and big data platforms

For details, see the documents of the third-party ETL tool.

DWS provides the DSC tool to migrate Teradata/Oracle scripts to DWS.

Provides abundant data sources and powerful data conversion capabilities through OBS.

Running the INSERT Statement to Insert Data

-

If you use an SQL client tool or JDBC/ODBC driver to connect to the DWS database, you can run the INSERT statement to insert one or more rows of data or to insert data from a specified table.

INSERT is the simplest way to write data. It is applicable to scenarios with small data volume and low concurrency.

Running the COPY FROM STDIN Statement to Import Data

Other files or databases

When you use Java to develop applications, the CopyManager interface of the JDBC driver is invoked to write data from files or other databases to DWS.

Data is directly written from other databases to DWS. Service data does not need to be stored in files.

Using a gsql Meta-Command \copy to Import Data

Local file

Different from the SQL COPY statement, the \copy command can read data from or write data into only local files on a gsql client.

This method is easy to operate and suitable for importing a small amount of data to the database.

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