I'm doing a RSS spider. How do you do for controlling the last crawl
date?
Right now what was I thinking is this:

Put in a control file the last pub_date that I have crawled. 
Then when the crawl starts, it checks the last pub_date against the
new pub_dates. If there are new items, then start crawling, if not, do
nothing.

How does everyone else resolve this?
I store all data in the database (including last crawl date and post dates) and take all dates I need from database.
Scrapy: RSS control pub_date