Date Parsing Performance: NSDateFormatter vs. SQLite

Jens Alfke:

vombat cleverly discovered that SQLite’s strftime function parses ISO-8601 (i.e. JSON) dates an order of magnitude faster than NSDateFormatter does, even with the overhead of having to generate and evaluate a SQL SELECT statement to run it.

I decided to go one step farther — I tweezed out the ~250 lines of C code from SQLite that implement the actual parsing, and got them to build independently. This adds another factor of 2x speed.

I enjoy reading the SQLite code. NSDateFormatter also seems to be responsible for Numbers’ horrific performance when opening CSV files.