> > This amounts to an assumption that you have infinite work_mem, in
> which
> > case you hardly need an external sort at all. If your
> work_mem is in
> > fact finite, then at some point you need more than two passes. I'm
> not
> > really interested in ripping out support for sort
> operations that are
> > much larger than work_mem.
>
> No it does not. I have explained this before. You can have
> one million files and merge them all into a final output with
> a single pass. It does not matter how big they are or how
> much memory you have.
Hh ? But if you have too many files your disk access is basically
then going to be random access (since you have 1000nds of files per
spindle).
From tests on AIX I have pretty much concluded, that if you read
256k blocks at a time though, random access does not really hurt that
much
any more.
So, if you can hold 256k per file in memory that should be sufficient.
Andreas