Database optimization questions when frequently deleting posts.

My blog is consists of temporary posts, about 200 a week. I coded it to autodelete the posts older than a month. My permalink structure is post_id/post_title/ .

I thought its a cool think cause its optimal to ask for post id from the database. BUT. is it optimal too when i delete msot of my posts so instead of coming ina row their ID is..

237 – 315 – 318 – 334 – 567 etcetc…

or i shouldnt deletemy old posts, rather move it toa category and exclude that category from the database – intensive queries??

what is the better practice?

thanks.