> When the set to be sorted is larger than can be handled in a memory
> only sort, does it make sense to write the data to a temporary file
> and perform a tag sort on the key values using the offset into that
> file of the required data as the tag?

This is what i wrote yesterday ;)

> That would eliminate all the
> page cache issues - and avoid churning the cache for other threads -
> while reducing the size of the data to be sorted. The temporary file
> would be written and read serially - relatively fast for a hard disk
> operation.

Written - yes, read - no.

Regards,
Vlad