Robert Haas wrote:
> If we arranged things so that the processes could use the data in the
> DSM directly rather than having to copy it out, we'd presumably save
> quite a bit of memory, since the whole structure would be shared
> rather than each backend having its own copy. But if the structure
> got too big to map (on a 32-bit system), then you'd be sort of hosed,
> because there's no way to attach just part of it. That might not be
> worth worrying about, but it depends on how big it's likely to get - a
> 32-bit system is very likely to choke on a 1GB mapping, and maybe even
> on a much smaller one.
How realistic it is that you would get a 1 GB mapping on a 32-bit
system? Each table entry is 106 bytes at the moment if my count is
right, so you need about one million tables to get that large a table.
It doesn't sound really realistic to have such a database on a smallish
machine.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services