duckdb.db keeps growing on frequent load of tpchsf1000

1. Drop tpch database if exist, create tpch database and tables
2. Load SF1000 data using duckdb udf example
SELECT run_in_duckdb('COPY tpch.lineitem FROM ''/mnt/nvme2/sf1000/lineitem.tbl'' (DELIMITER ''|'')');

3. Repeat step1

Keep a tab on disk size of folder where you have duckdb data like default
du -sh /var/lib/mysql/*

You will find 2 files related to duckdb
527G /var/lib/mysql/duckdb.db <--- This keeps growing
20M /var/lib/mysql/duckdb.db.wal <--- This is undercheck because of setting wal_autocheckpoint 256.0 MiB

Problem: you may run out of disk space if duckdb.db doesnot shrink , which it should on drop database so it could be case of disk fragementation