I wrote a blog post called How SQL Server Sorts the UNIQUEIDENTIFIER Type and another one called Ordering the SQL UNIQUEIDENTIFIER Type Numerically Correct for Reporting a while back. As a result, I get a lot of e-mails from people struggling with UNIQUEIDENTIFIER values in Microsoft SQL Server. That's cool because I like helping other developers. The mistake that most people make when working with this data type is treating them like strings. However, UNIQUEIDENTIFIERS are absurd looking integers, really big ones. We show them in hexadecimal format to make them more compact which adds to their absurdness, I suppose.

When iterating over a sequence of numbers in Python, the range() function is commonly used. However, the implementation of the range() function in Python 2.x instantiates each element in the sequence before the iteration begins. This is really costly from both memory and CPU perspectives when the desired range of numbers is large. Consider using the xrange() function instead which implements a Python generator to yield each number in the sequence as needed. Using xrange() instead of range() for large iterations can have a big, positive impact on your code. For example, in an application I was working on recently, replacing range() calls with xrange() boosted my performance from ~900,000 transactions per second to over 3,000,000. In Python 3.x, the range() function is supposed to be implemented as a generator but I haven't tested that to be true yet. Let me know if you have.