expanding our usage of POSIX_FADVISE

Hello,

I wonder if POSIX_FADV_RANDOM and POSIX_FADV_SEQUENTIAL are still innacurate
for postgreSQL ?

I find
«A related problem is that the smgr uses the same FD to access the same
relation no matter how many scans are in progress. Think about a complex query
that is doing both a seqscan and an indexscan on the same relation (a self-
join could easily do this). You'd really need to change this if you want
POSIX_FADV_SEQUENTIAL and POSIX_FADV_RANDOM to get set usefully.
» (tom lane, 2003)

And also :
«
Surely POSIX_FADV_SEQUENTIAL is the one intended to hint seq scans, and
POSIX_FADV_RANDOM to hint random access. No?
ISTM, _WILLNEED seems just right for small random-access blocks.
Anyway, for those who want to see what they do in Linux,
http://www.gelato.unsw.edu.au/lxr/source/mm/fadvise.c Pretty scary that Bruce
said it could make older linuxes dump core - there isn't a lot of code there.
» (ron mayer, 2006)

But that seems a bit old.
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Cédric Villemain
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