AW: Why vacuum?

> > Yes, postgresql requires vacuum quite often otherwise queries and
> > updates start taking ungodly amounts of time to complete. If you're
> > having problems because vacuum locks up your tables for too long
> > you might want to check out:
>
> But why? I don't know of other databases that need to be
> 'vacuum'ed. Do
> all others just do it internaly on a regular basis?
>
> What am I missing here?

They all have an overwriting storage manager. The current storage manager
of PostgreSQL is non overwriting, which has other advantages.

There seem to be 2 answers to the problem:
1. change to an overwrite storage manager
2. make vacuum concurrent capable

The tendency here seems to be towards an improved smgr.
But, it is currently extremely cheap to calculate where a new row
needs to be located physically. This task is *a lot* more expensive
in an overwrite smgr. It needs to maintain a list of pages with free slots,
which has all sorts of concurrency and persistence problems.

Andreas