Thread: [pgsql-www] technical updates to postgresql.org (db size / parallell query)

https://www.postgresql.org/about/
|There are active PostgreSQL systems in production environments that manage in
|excess of 4 terabytes of data.

I think that gives the impression that PG isn't regularly used with larger
data, and should either be removed or (periodically) updated.  I don't expect
we're near the technical or other limitations, but at least two of our
customers have DBs currently 10-20TB and continuing to grow.

https://wiki.postgresql.org/wiki/FAQ#How_does_PostgreSQL_use_CPU_resources.3F
|The PostgreSQL server is process-based (not threaded), and uses one operating
|system process per database session. A single database session (connection)
|cannot utilize more than one CPU. Of course, multiple sessions are
|automatically spread across all available CPUs by your operating system. Client
|applications can easily use threads and create multiple database connections
|from each thread.
|
|A single complex and CPU-intensive query is unable to use more than one CPU to
|do the processing for the query. The OS may still be able to use others for
|disk I/O etc, but you won't see much benefit from more than one spare core. 

I think should mention that PG96 introduces parallel query.
https://www.postgresql.org/docs/9.6/static/parallel-query.html

Justin

On 08/12/2017 09:05 PM, Justin Pryzby wrote:
> https://www.postgresql.org/about/
> |There are active PostgreSQL systems in production environments that manage in
> |excess of 4 terabytes of data.
>
> I think that gives the impression that PG isn't regularly used with larger
> data, and should either be removed or (periodically) updated.  I don't expect
> we're near the technical or other limitations, but at least two of our
> customers have DBs currently 10-20TB and continuing to grow.

the entire /about page is in serious need of a major overhaul - this has 
been mentioned^complained about a number of times before but nobody has 
yet started the bikesheding on an actual wording by proposing a patch ;)

The same goes for some other pages (/awards, /casestudies and 
/advantages being the worst ones imho)


>
> https://wiki.postgresql.org/wiki/FAQ#How_does_PostgreSQL_use_CPU_resources.3F
> |The PostgreSQL server is process-based (not threaded), and uses one operating
> |system process per database session. A single database session (connection)
> |cannot utilize more than one CPU. Of course, multiple sessions are
> |automatically spread across all available CPUs by your operating system. Client
> |applications can easily use threads and create multiple database connections
> |from each thread.
> |
> |A single complex and CPU-intensive query is unable to use more than one CPU to
> |do the processing for the query. The OS may still be able to use others for
> |disk I/O etc, but you won't see much benefit from more than one spare core.
>
> I think should mention that PG96 introduces parallel query.
> https://www.postgresql.org/docs/9.6/static/parallel-query.html

thats however a wiki - please get an account and assciated editor 
permissions and hack away :)


Stefan

On Sat, Aug 12, 2017 at 10:16:01PM +0200, Stefan Kaltenbrunner wrote:
> On 08/12/2017 09:05 PM, Justin Pryzby wrote:
> >https://wiki.postgresql.org/wiki/FAQ#How_does_PostgreSQL_use_CPU_resources.3F
[...]
> >I think should mention that PG96 introduces parallel query.
> >https://www.postgresql.org/docs/9.6/static/parallel-query.html
> 
> thats however a wiki - please get an account and assciated editor
> permissions and hack away :)

On Tue, May 29, 2018 at 08:47:13PM -0400, Alvaro Herrera wrote:
> On 2018-May-29, Justin Pryzby wrote:
> > I'm requesting wiki editor privs for user:justinpryzby.
> Granted.

Thank you :)

I finally changed:

https://wiki.postgresql.org/index.php?title=FAQ&diff=32001&oldid=30780
|How does PostgreSQL use CPU resources?
|The PostgreSQL server is process-based (not threaded). Each database session
|connects to a single PostgreSQL operating system (OS) process. Multiple
|sessions are automatically spread across all available CPUs by the OS. The OS
|also uses CPUs to handle disk I/O and run other non-database tasks. Client
|applications can use threads, each of which connects to a separate database
|process. Since version 9.6, portions of some queries can be run in parallel, in
|separate OS processes, allowing use of multiple CPU cores. Parallel queries are
|enabled by default in version 10 (max_parallel_workers_per_gather), with
|additional parallelism expected in future releases. 

Justin