Adam wrote:
On Fri, 19 Aug 2005 17:08:36 +1000 Graeme Lee <[EMAIL PROTECTED]>
wrote:
This is very much off topic, but you seem to be misunderstanding me.
The shared buffer is used by all the postmaster processes as a shared
memory pool for selects/inserts/updates on the table space. The disk
buffer is next stage where the os decides what to do with reads/
writes etc.
The shared buffer cache is use to cache data read from disk. In what
way is that not a disk cache? Yes, the filesystem buffer cache is a
disk cache too, I never said it wasn't. But your statement that
postgresql does not maintain its own disk cache is simply wrong, the
shared buffer cache is a disk cache, it caches data read from disk, to
prevent future reads from disk. And the advice to increase
BUFCACHEPERCENT is misguided. For a dedicated postgresql database
server you are better off using extra RAM for postgresql's cache, not
the filesystem's.
It was a suggestion. And the shared buffer cache is still not a disk cache.
http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html
http://www.powerpostgresql.com/PerfList/
Postgresql does have a disk cache.
See above links
G
