HeatWave User Guide  /  Preparing Data  /  Excluding Table Columns

3.2 Excluding Table Columns

Before loading a table into HeatWave, identify table columns to exclude. Columns to exclude are:

  • Columns with unsupported data types. It is required that these columns are excluded; otherwise, the table cannot be loaded. For a list of data types that HeatWave supports, see Section 10.1, “Supported Data Types”.

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

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

Queries that access columns defined with the NOT SECONDARY attribute are executed on the MySQL DB system by default.