Hi Kevin,

One thing you should realise is that neither NOLOCK or READPAST do anything to improve query performance at all. All they do is control concurrency, which can have the benefit of seemingly make things look quicker when many processes are trying to access the same data.

I would probably never use READPAST as this can give you different results every time. READPAST ignores locked data and doesn't return it. Whereas NOLOCK still returns that data, albeit giving you potentially dirty data.

If you select from a table that would typicall return 100 rows, when using READPAST, if 10 of those rows are being updated, then you'd only get back 90 rows. With NOLOCK you'd get back all 100 rows.

So as long as you're aware of the drawbacks of using NOLOCK (and you can live with it) and if you're dealing with concurrency problems then NOLOCK can be of benefit.