With the database, run a mysqldump --no-data one time so you have the schema for your tables. Each time you need to clear the database, rename the old one, recreate the new one, and import the mysqldump file to recreate the tables.
But you aren't going to run into performance issues leaving your records in your database until you get into the millions of rows. If you tweak your servers correctly you won't see performance issues.
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