Hologres:Create a Hologres foreign table mapped to MaxCompute

Create a foreign table

1. Log on to the Hologres console.

2. In the top navigation bar, select a region from the drop-down list.

3. In the left-side navigation pane of the Hologres console, click Go to HoloWeb to go to the HoloWeb console.

4. In the main menu bar of the HoloWeb console, choose Metadata Management > MaxCompute Query Acceleration > Create Foreign Table. In the Acceleration Method section of the page that appears, select Single Table.

   You can also click Instances Connected in the left-side navigation pane of the Metadata Management tab. Click the name of the instance that you want to manage and click the name of the database that you want to manage. Right-click the name of the schema that you want to manage and select Create MaxCompute External Table.

5. In the Acceleration Method section of the page that appears, select Single Table and configure the parameters.

   Category	Parameter	Description
   Acceleration Method	Select an acceleration method.	Valid values: Entire Project Selected Tables Single Table
   Source MaxCompute Table	Project Name	The name of the MaxCompute project.
   	Schema Name	The name of the schema in which the MaxCompute table resides. If your MaxCompute project uses the two-layer model, this parameter is not displayed by default. If your MaxCompute project uses the three-layer model, you can select an authorized schema from the drop-down list. For information about the schema feature, see Schema-related operations.
   	Table Name	The name of the MaxCompute table. Prefix-based fuzzy search is supported. Note This parameter is required only if you set the Acceleration Method parameter to Single Table.
   Destination Hologres Table	Schema	The name of the schema. You can select the default schema named public or a custom schema.
   	Table Name	The name of the Hologres foreign table. The name of the source MaxCompute table is automatically specified for this parameter. You can also manually rename the table.
   	Destination Table Description	The description of the Hologres foreign table that you create. You can specify a description based on your business requirements.

   Note

   When you create a foreign table to synchronize data from a MaxCompute table, comments of both field names and columns of the MaxCompute table are synchronized to the foreign table.

6. Click Submit. After you submit the foreign table, you can refresh the left-side instance list. The created foreign table is displayed in the schema that you selected.

7. Optional. On the page of the foreign table that you create, click Query Table in the upper-right corner to go to the SQL query window and execute standard PostgreSQL statements to analyze data.

Edit a foreign table

1. In the left-side navigation pane, click Instances Connected. All the connected instances are displayed.

2. Click the name of the instance that you want to manage. All the created databases are displayed.

3. Click the name of the database that you want to manage, click the name of the schema that you want to manage, and then click Foreign Tables. All the created foreign tables are displayed.

4. Right-click the name of the foreign table that you want to manage, select Open Table, and then click Edit Table in the upper-right corner.

5. Modify the fields and partitions of the foreign table that is sourced from the MaxCompute table based on your business requirements.

6. Click Submit. The foreign table is edited.

Rename a foreign table

1. In the left-side navigation pane, click Instances Connected. Find the foreign table that you want to manage.

   For more information about how to query a foreign table, see Step 1 to Step 3 in Edit a foreign table.

2. Right-click the name of the foreign table and select Rename.

3. In the message that appears, click OK.

Delete a foreign table

1. In the left-side navigation pane, click Instances Connected. Find the foreign table that you want to manage.

   For more information about how to query a foreign table, see Step 1 to Step 3 in Edit a foreign table.

2. Right-click the name of the foreign table and select Delete Table.

3. In the message that appears, click OK.

Preview data

1. In the left-side navigation pane, click Instances Connected. Find the foreign table that you want to manage.

   For more information about how to query a foreign table, see Step 1 to Step 3 in Edit a foreign table.

2. Double-click the name of the foreign table. On the foreign table page, click Data Preview.

References

You can also use SQL statements to create, modify, and drop foreign tables. For more information, see the following topics:

• CREATE FOREIGN TABLE

• IMPORT FOREIGN SCHEMA

• ALTER FOREIGN TABLE

• DROP FOREIGN TABLE