Warm-up cache may have its virtue

Hinted by this thread:

http://archives.postgresql.org/pgsql-performance/2006-01/msg00016.php

I wonder if we should really implement file-system-cache-warmup strategy
which we have discussed before. There are two natural good places to do
this:

(1) sequentail scan
(2) bitmap index scan

We can consider (2) as a generalized version of (1). For (1), we have
mentioned several heuristics like keep scan interval to avoid competition.
These strategy is also applable to (2).

Question: why file-system level, instead of buffer pool level? For two
reasons: (1) Notice that in the above thread, the user just use
"shared_buffers = 8192" which suggest that file-system level is already
good enough; (2) easy to implement.

Use t*h*r*e*a*d? Well, I am a little bit afraid of mention this word.
But we can have some dedicated backends to do this - like bgwriter.

Let's dirty our hands!

Comments?

Regards,
Qingqing