In dbt incremental merge strategy we need ability to choose the temporary table configurations (CTAS)

[hpasumarthi]

hello Team,
While working with Iceberg tables we have realised that temporary table which is created as a part of the incremental merge tries to match the schema of the target table.

During our test we have observed that tmp table with same schema as target table is performance degrader is there any way we can fix this via dbt-hive adaptor.
Our testing scenario is

Source table :: External table + parquet format + partition by date.
Target table :: Iceberg table + parquet format + partition spec by date.

our requirement is temporary table which is create as a part of incremental merge shows better performance when it is
temp_table :: External table + parquet format (no partitions & no iceberg)