Help Center/ GaussDB(DWS)/ More Documents/ Developer Guide (Kuala Lumpur Region)/ Data Migration/ Data Export/ Exporting Data to OBS/ Exporting CSV/TXT Data to OBS/ Examples
Updated on 2022-08-16 GMT+08:00
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Examples

Exporting a Table

Create two foreign tables and use them to export tables from a database to two buckets in OBS.

  1. Log in to the OBS data server through the management console. On the OBS server, create the buckets /input-data1 and /input-data2 for storing data files, and create data directories /input-data1/data and /input-data2/data, respectively, in the two buckets.
  2. On the GaussDB(DWS) database, create the foreign tables tpcds.customer_address_ext1 and tpcds.customer_address_ext2 for the OBS data server to receive data exported from the database.

    OBS and the database are in the same region. The example GaussDB(DWS) table to be exported is tpcds.customer_address.

    Export information is set as follows:

    • The source data file directories are /input-data1/data/ and /input-data2/data/, so location of tpcds.customer_address_ext1 and tpcds.customer_address_ext2 is set to obs://input-data1/data/ and obs://input-data2/data/, respectively.

    Information about data formats is set based on the detailed data format parameters specified during data export from a database. The parameter settings are as follows:

    • format is set to CSV.
    • encoding is set to UTF-8.
    • delimiter is set to E'\x08'.
    • Configure encrypt. Its default value is off.
    • access_key is set to the AK you have obtained. (mandatory)
    • secret_access_key is set to the SK you have obtained. (mandatory)

      access_key and secret_access_key have been obtained during user creation. Replace the italic part with the actual keys.

    Based on the preceding settings, the foreign table is created using the following statements:

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    CREATE FOREIGN TABLE tpcds.customer_address_ext1
(
ca_address_sk             integer                       ,
ca_address_id             char(16)                      ,
ca_street_number          char(10)                      ,
ca_street_name            varchar(60)                   ,
ca_street_type            char(15)                      ,
ca_suite_number           char(10)                      ,
ca_city                   varchar(60)                   ,
ca_county                 varchar(30)                   ,
ca_state                  char(2)                       ,
ca_zip                    char(10)                      ,
ca_country                varchar(20)                   ,
ca_gmt_offset             decimal(5,2)                  ,
ca_location_type          char(20)
)
SERVER gsmpp_server
OPTIONS(LOCATION 'obs://input-data1/data/',
FORMAT 'CSV',
ENCODING 'utf8', 
DELIMITER E'\x08', 
ENCRYPT 'off',
ACCESS_KEY 'access_key_value_to_be_replaced',
SECRET_ACCESS_KEY 'secret_access_key_value_to_be_replaced' 
)Write Only;

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    CREATE FOREIGN TABLE tpcds.customer_address_ext2
(
ca_address_sk             integer                       ,
ca_address_id             char(16)                      ,
ca_street_number          char(10)                      ,
ca_street_name            varchar(60)                   ,
ca_street_type            char(15)                      ,
ca_suite_number           char(10)                      ,
ca_city                   varchar(60)                   ,
ca_county                 varchar(30)                   ,
ca_state                  char(2)                       ,
ca_zip                    char(10)                      ,
ca_country                varchar(20)                   ,
ca_gmt_offset             decimal(5,2)                  ,
ca_location_type          char(20)
)
SERVER gsmpp_server
OPTIONS(LOCATION 'obs://input-data2/data/',
FORMAT 'CSV',
ENCODING 'utf8', 
DELIMITER E'\x08', 
ENCRYPT 'off',
ACCESS_KEY 'access_key_value_to_be_replaced',
SECRET_ACCESS_KEY 'secret_access_key_value_to_be_replaced'
)Write Only;

  3. In GaussDB(DWS), export the data table tpcds.customer_address to the foreign tables tpcds.customer_address_ext1 and tpcds.customer_address_ext2 concurrently. 

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    INSERT INTO tpcds.customer_address_ext1 SELECT * FROM tpcds.customer_address;

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    INSERT INTO tpcds.customer_address_ext2 SELECT * FROM tpcds.customer_address;

    The design of OBS foreign tables does not allow exporting files to a non-empty path. However, in concurrent export scenarios, multiple files are exported to the same path, causing an error.

    Assume that a user concurrently exports data from the same table to the same OBS foreign table, and that one SQL statement is executed to export data when another SQL statement is being executed and has not generated any file on the OBS server. In this case, certain data is overwritten although both SQL statements are successfully executed. Therefore, you are advised not to concurrently export data to the same OBS foreign table.

Concurrently Exporting Tables

Use the two foreign tables to export tables from the database to two buckets in OBS.

  1. Log in to the OBS data server through the management console. On the OBS server, create the buckets /input-data1 and /input-data2 for storing data files, and create data directories /input-data1/data and /input-data2/data, respectively, in the two buckets.
  2. In GaussDB(DWS), create foreign tables tpcds.customer_address_ext1 and tpcds.customer_address_ext2 for the OBS server to receive exported data.

    OBS and the database are in the same region. Tables to be exported are tpcds.customer_address and tpcds.customer_demographics.

    Export information is set as follows:
    • The source data file directories are /input-data1/data/ and /input-data2/data/, so location of tpcds.customer_address_ext1 and tpcds.customer_address_ext2 is set to obs://input-data1/data/ and obs://input-data2/data/, respectively.

    Information about data formats is set based on the detailed data format parameters specified during data export from GaussDB(DWS). The parameter settings are as follows:

    • format is set to CSV.
    • encoding is set to UTF-8.
    • delimiter is set to E'\x08'.
    • Configure encrypt. Its default value is off.
    • access_key is set to the AK you have obtained. (mandatory)
    • secret_access_key is set to the SK you have obtained. (mandatory)

      access_key and secret_access_key have been obtained during user creation. Replace the italic part with the actual keys.

    Based on the preceding settings, the foreign table is created using the following statements:

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    CREATE FOREIGN TABLE tpcds.customer_address_ext1
(
ca_address_sk             integer               ,
ca_address_id             char(16)              ,
ca_street_number          char(10)                      ,
ca_street_name            varchar(60)                   ,
ca_street_type            char(15)                      ,
ca_suite_number           char(10)                      ,
ca_city                   varchar(60)                   ,
ca_county                 varchar(30)                   ,
ca_state                  char(2)                       ,
ca_zip                    char(10)                      ,
ca_country                varchar(20)                   ,
ca_gmt_offset             decimal(5,2)                  ,
ca_location_type          char(20)
)
SERVER gsmpp_server
OPTIONS(LOCATION 'obs://input-data1/data/',
FORMAT 'CSV',
ENCODING 'utf8', 
DELIMITER E'\x08',
ENCRYPT 'off',
ACCESS_KEY 'access_key_value_to_be_replaced',
SECRET_ACCESS_KEY 'secret_access_key_value_to_be_replaced' 
)Write Only;

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    CREATE FOREIGN TABLE tpcds.customer_address_ext2
(
ca_address_sk             integer               ,
ca_address_id             char(16)              ,
ca_address_name           varchar(20)           ,
ca_address_code           integer               ,
ca_street_number          char(10)                      ,
ca_street_name            varchar(60)                   ,
ca_street_type            char(15)                      ,
ca_suite_number           char(10)                      ,
ca_city                   varchar(60)                   ,
ca_county                 varchar(30)                   ,
ca_state                  char(2)                       ,
ca_zip                    char(10)                      ,
ca_country                varchar(20)                   ,
ca_gmt_offset             decimal(5,2)                  
)
SERVER gsmpp_server
OPTIONS(LOCATION 'obs://input_data2/data/',
FORMAT 'CSV',
ENCODING 'utf8', 
DELIMITER E'\x08', 
QUOTE E'\x1b',
ENCRYPT 'off',
ACCESS_KEY 'access_key_value_to_be_replaced',
SECRET_ACCESS_KEY 'secret_access_key_value_to_be_replaced'
)Write Only;

  3. In GaussDB(DWS), export the data tables tpcds.customer_address and tpcds.warehouse in parallel to the foreign tables tpcds.customer_address_ext1 and tpcds.customer_address_ext2, respectively. 

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    INSERT INTO tpcds.customer_address_ext1 SELECT * FROM tpcds.customer_address;

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    INSERT INTO tpcds.customer_address_ext2 SELECT * FROM tpcds.warehouse;