Re: A couple of patches for PostgreSQL 64bit support

Tom Lane wrote:
> Koichi Suzuki <koichi@intellilink.co.jp> writes:
>
>>Here're a couple of patches for PostgreSQL 64bit support.  There're just
>>two extension to 64bit, size of shared memory and transaction ID.
>
>
> I asked originally for some experimental evidence showing any value
> in having more than 2Gb of shared buffers.  In the absence of any
> convincing demonstration, I'm not very inclined to worry about whether
> we can handle wider-than-int shared memory size.

There is some practical evidence. Recently the number of large boxes in
the field is almost growing exponentially. Today I have heard somebody
say "this box has 'just 4 gig of ram' ".
On large installations we have already seen problems with too small
caches (= 2gb).
Surprisingly this has turned out to be a quite important issue in the
field. Tests have shown that the cache provided by the OS is a lot worse
for the database.

64-bit XIDs seem to be an overkill - the only practical impact I can see
is an even larger tuple header (this can be an issue on large boxes too
- at least compared to Oracle).

    Best regards,

        Hans