Hervé Piedvache wrote:
> Hi,
>
> A simple question about PostgreSQL ... I have a Pentium Xeon Quadri processors
> ...
> If I do a SQL request ... does PostgreSQL use one or more processor ?
PostgreSQL uses one processor per connection. If you have 4 simultaneous
connections, you'll use all four processors (assuming your operating system
is properly designed/configured).
> And if it use only one ... why ?
> Could you explain me this ;o)
The answer to that is beyond my knowledge, but I have a few guesses:
1) Doing so is more complicated than you think.
2) The code was originally written for uniprocessor machines, and nobody
has volunteered to update it yet.
3) kernel threading isn't as predictable as some people would like to
think, thus they developers have avoided using it so far.
4) It simply isn't practical to expect a single query to
execute on multiple processors simultaneously.
Do you know of any RDBMS that actually will execute a single query on
multiple processors?
--
Bill Moran
Potential Technologies
http://www.potentialtech.com