Realtime Compute for Apache Flink:Manage Hologres catalogs

Create a Hologres table

When you create a Hologres table, you can configure physical table properties in the WITH clause. You can configure table property settings based on your business requirements to sort and query data in an efficient manner. The following table describes the supported property parameters and examples. The parameters whose names start with the table_property. prefix indicate physical table properties.

Modify a Hologres table

The following examples show the modifications that you can make on a Hologres table.

• Modify table properties

  ALTER TABLE `${catalog_name}`.`${db_name}`.`${schema_name.table_name}` SET (
    'table_property.binlog.level' = 'replica',
    'table_property.binlog.ttl' = '64700'
  );

  Note

  You can modify only some table properties. For more information, see Create a Hologres table.

• Rename a table

  ALTER TABLE `${catalog_name}`.`${db_name}`.`${schema_name.table_name}` 
  RENAME TO `${catalog_name}`.`${db_name}`.`${schema_name.new_table_name}`;

• Add columns to a table

  ALTER TABLE `${catalog_name}`.`${db_name}`.`${schema_name.table_name}` 
  ADD <column_name> <column_datatype> COMMENT '<column_comment>';

• Modify the name of a column

  ALTER TABLE `${catalog_name}`.`${db_name}`.`${schema_name.table_name}` 
  RENAME <old_column_name> TO <new_column_name>;

• Modify the comment of a column

  ALTER TABLE `${catalog_name}`.`${db_name}`.`${schema_name.table_name}` 
  MODIFY <column_name> <original_column_type> COMMENT '<new_column_comment>';

Read data from a Hologres table

INSERT INTO ${other_sink_table}
SELECT ...
FROM `${catalog_name}`.`${db_name}`.`${schema_name.table_name}`

Insert result data into a Hologres table

INSERT INTO `${catalog_name}`.`${db_name}`.`${schema_name.table_name}`
SELECT ... 
FROM ${other_source_table}

Use the Hologres catalog that you created as the catalog of the destination store that is used in the CREATE TABLE AS statement

CREATE TABLE IF NOT EXISTS `${catalog_name}`.`${db_name}`.`${schema_name.table_name}`
WITH (
  'connector' = 'hologres'
) AS TABLE ${other_source_table};

The CREATE TABLE AS statement allows you to configure physical table attributes in the WITH clause. When you create a destination table, you can configure these attributes for the table. For more information about the table properties supported by Hologres catalogs, see Create a Hologres table.

Use the Hologres catalog that you created as the catalog of the destination store that is used in the CREATE DATABASE AS statement

CREATE DATABASE IF NOT EXISTS `${catalog_name}`.`${db_name}`
WITH (
  'sink.parallelism' = '5' -- Specify the degree of parallelism for each result table. 
) AS DATABASE ${other_source_database};

During data synchronization, you can declare the parameters of the result table in the WITH clause. When the job starts, these parameters take effect on the result tables to which you want to synchronize data. For more information about the parameters that can be modified, see Create a Hologres result table.