Update attribute columns of a mapping table

Tablestore SDK for Python adds or removes attribute columns of a mapping table.

Prerequisites

Install Tablestore SDK for Python and initialize a client.
SQL query requires version 5.4.2 or later. We recommend that you use the latest version.

Only mapping tables created by a CREATE TABLE statement support ALTER TABLE. Mapping tables automatically bound by operations such as DESCRIBE cannot be updated.
Each ALTER TABLE statement can add or remove only one attribute column.
The operation updates only the mapping table schema. It does not update the Tablestore storage schema and cannot add or remove primary key columns.
The SQL engine refreshes the mapping table asynchronously within 30 seconds. During the refresh, a query for all attribute columns may not return a newly added column.
To change an existing attribute column definition, remove the column and then add it with the new definition.

Call the exe_sql_query method to execute an ALTER TABLE statement and add or remove an attribute column.

def exe_sql_query(self, query)

The following example adds the new_column attribute column to example_table.

query = "ALTER TABLE example_table ADD COLUMN new_column BIGINT"
client.exe_sql_query(query)

The exe_sql_query method contains the following parameter.

Name

Type

Description

query (required)

String

The ALTER TABLE statement to execute.

To add an attribute column, use ALTER TABLE <mapping_table_name> ADD COLUMN <column_name> <data_type>.

To remove an attribute column, use ALTER TABLE <mapping_table_name> DROP COLUMN <column_name>.

The following example removes new_column from example_table.

query = "ALTER TABLE example_table DROP COLUMN new_column"
client.exe_sql_query(query)