Re: Caching by Postgres

Donald Courtney wrote:
> I built postgreSQL 8.1 64K bit on solaris 10 a few months ago
> and side by side with the 32 bit postgreSQL build saw no improvement. In
> fact the 64 bit result was slightly lower.

I'm not surprised 32-bit binaries running on a 64-bit OS would be faster
than 64-bit/64-bit. 64-bit isn't some magical wand you wave and it's all
ok. Programs compiled as 64-bit will only run faster if (1) you need
64-bit address space and you've been using ugly hacks like PAE to get
access to memory > 2GB or (2) you need native 64-bit data types and
you've been using ugly hacks to piece 32-bit ints together (example,
encryption/compression). In most cases, 64-bit will run slightly slower
due to extra overhead of using larger datatypes.

Since PostgreSQL hands off the majority of memory management/data
caching to the OS, only the OS needs to be 64-bit to reap the benefits
of better memory management. Since Postgres *ALREADY* reaps the 64-bit
benefit, I'm not sure how the argument moving caching/mm/fs into
Postgres would apply. Yes there's the point about possibly implementing
better/smarter/more appropriate caching algorithms but that has nothing
to do with 64-bit.