The type of Snowflake table that persists until it is explicitly dropped, is available for all users with relevant privileges across sessions, and does not have a Fail-safe period, is a Transient table. Transient tables are designed to provide temporary storage similar to permanent tables but with some reduced storage costs and without the Fail-safe feature, which provides additional data protection for a period beyond the retention time.
Transient tables are useful in scenarios where data needs to be temporarily stored for longer than a session but does not require the robust durability guarantees of permanent tables.

* Processing data in smaller batches reduces resource pressure during execution.
* Increasing warehouse size provides more memory and CPU, which helps reduce memory spillage, where intermediate data is written to disk.
Reference:
Snowflake Docs: Query Performance Tuning

The MERGE command in Snowflake is used for incremental loading based on column values in a source table or subquery. It enables the insertion, updating, or deletion of records in a target table depending on whether matching rows are found, making it ideal for loading data that changes incrementally, such as daily updates or modifications.