自動VACUUM実行中に手動VACUUMを実行するとどうなるか

自動VACUUM実行中に手動VACUUMを実行すると、自動VACUUMが停止し、手動VACUUMが実行される。

Automatic vacuum operations pause if any of the following conditions are met:

• A user runs a data definition language (DDL) operation, such as ALTER TABLE, that requires an exclusive lock on a table that automatic vacuum is currently working on.
• A user triggers VACUUM on any table in the cluster (only one VACUUM can run at a time).
• A period of high cluster load.

VACUUM - Amazon Redshift