Tom Lane wrote:
"Joshua D. Drake" <jd@xxxxxxxxxxxxxxxxx> writes:
I use RHEL 4. I can not understand how the scalability related with
shared memory?
It isn't RHEL4 and shared memory. It is PostgreSQL and shared memory.
Things have changed with PostgreSQL since 7.3 (7.3 is really god awful
old) that allow it to more effectively access shared memory and thus
provide better performance.
Some specifics:
* bufmgr algorithms redesigned to allow larger number of shared buffers
to be used effectively
* bufmgr redesigned to not have a single lock for management of all
shared buffers; likewise for lockmgr
* lots of marginal tweaks such as paying attention to cache line
alignment of "hot" shared data structures
I'm probably forgetting some things but I think the bufmgr and lockmgr
changes were the biggest improvements in this area.
regards, tom lane
That is very helpful. Thanks!
Xiaoning
