2.2.2.1 Excluding Table Columns

Before loading a table into HeatWave, columns with unsupported data types must be excluded; otherwise, the table cannot be loaded. For a list of data types that HeatWave supports, see Section 2.10, “Supported Data Types”.

Optionally, exclude columns that are not relevant to the intended queries. Excluding irrelevant columns is not required but doing so reduces load time and the amount of memory required to store table data.

To exclude a column, specify the NOT SECONDARY column attribute in an ALTER TABLE or CREATE TABLE statement, as shown below. The NOT SECONDARY column attribute prevents a column from being loaded into HeatWave when executing a table load operation.

mysql> ALTER TABLE tbl_name MODIFY description BLOB NOT SECONDARY;

mysql> CREATE TABLE orders (id INT, description BLOB NOT SECONDARY);

Note

If a query accesses a column defined with the NOT SECONDARY attribute, the query is executed on the MySQL DB System by default.

To include a column that was previously excluded, refer to the procedure described in Section 2.4, “Modifying Tables”.