MySQL :: HeatWave User Guide :: 4.5.2 List Excluded Columns

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4.5.2 List Excluded Columns

In MySQL HeatWave, you can explicitly exclude certain table columns from being loaded into the MySQL HeatWave Cluster, by defining them with the NOT SECONDARY attribute. These columns are typically not needed for analytic queries and are therefore omitted to optimize memory usage and performance.

Before You Begin

Ensure that the enable_secondary_engine_statistics system variables is set to ON.
Check if you have the SELECT and INSERT privileges for the table that you want to analyze. If not, ask your admin user to grant you the required privileges.

Viewing Excluded Columns

To identify table columns defined as NOT SECONDARY on the DB System, query the EXTRA column of the INFORMATION_SCHEMA.COLUMNS table. Columns defined with the NOT SECONDARY column attribute are not loaded into MySQL HeatWave when executing a table load operation.

mysql> SELECT COLUMN_NAME, EXTRA 
          FROM INFORMATION_SCHEMA.COLUMNS
          WHERE TABLE_NAME LIKE 't1' AND EXTRA LIKE '%NOT SECONDARY%';
+-------------+---------------+
| COLUMN_NAME | EXTRA         |
+-------------+---------------+
| O_COMMENT   | NOT SECONDARY |
+-------------+---------------+

You can also view columns defined as NOT SECONDARY for an individual table using SHOW CREATE TABLE.

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