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, you can also exclude columns that are not relevant to the queries you intend to run. 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
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 orders MODIFY description BLOB NOT SECONDARY;
mysql> CREATE TABLE orders (id INT, description BLOB NOT SECONDARY);
If a query accesses a column defined with the
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”.