> > 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 ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
