page cache

Two examples of escaping data are the following:

• Before you insert a value into a SQL query, using for example mysqli::real_escape_string() or PDO::quote().
• Before you insert data into your output html, using htmlspecialchars().

The question I'd like to ask today is, when to do this?

There are two possible moments:

The Zend Developer Zone has pointed out a new white paper (written up by Shahar Evron of Zend) about data caching with the Zend Server product Zend offers.